Abstract:
The invention relates to a device ( 10; 10   a ) for encapsulating a component ( 1 ) with plastic material ( 2 ), comprising at least two tool parts ( 11, 12 ), which in a closed arrangement for encapsulating the component ( 1 ) form a receptacle ( 15 ) for the component ( 1 ), an injection channel ( 30 ) for supplying the liquefied plastic material ( 2 ) to the region of the receptacle ( 15 ), and a single retaining element ( 22 ) for positioning the component ( 1 ) in the receptacle ( 15 ), wherein the retaining element ( 22 ) can be moved in a first position for positioning the component ( 1 ) in the receptacle ( 15 ) and in a second position for preferably completely encapsulating the component ( 1 ) with the plastic material ( 2 ). According to the invention, the retaining element ( 22 ) holds the component ( 1 ) in the region of the receptacle ( 15 ) by means of form positive and/or clamping engagement.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a device for encapsulating a component with plastics material. 
     Such a device is known from DE 10 2007 036 264 A1. The known device has a tool consisting of two tool halves, which are movable with respect to one another, and in the closed state form a receptacle for the encapsulation of a component. In one tool half there is formed a through-opening, in which a slide is arranged in a longitudinally movable manner, serving for positioning the component to be encapsulated. In the previously known document, the component to be encapsulated is an element of a permanent magnet, so that it can be positioned merely by being placed on the planar surface of the pin-shaped holding element consisting of metal. As soon as the component to be encapsulated is encapsulated in certain regions and the plastics material has set, the holding element can be retracted in its through-bore, after which the not yet encapsulated region of the component can then be encapsulated with plastics material in a second encapsulating step. The positioning of a component to be encapsulated by means of a single holding element is problematic if this element is not for example positioned by magnetic action, as in the previously known document. 
     Therefore, DE 196 20 002 B4 discloses a further device for encapsulating a component in which four holding pins are provided for positioning the component to be encapsulated and can be brought up against the component from two sides by being inserted into recesses in the component. However, such a device equipped with multiple holding elements is of a relatively complex construction, since the holding elements have to be movably arranged. In addition, the use of multiple holding elements is possibly restricted by the geometry of the component to be encapsulated, or multiple steps are required for encapsulating the component until it is completely encapsulated. 
     SUMMARY OF THE INVENTION 
     Against the background of the prior art presented, the invention is based on the object of developing a device for encapsulating a component with plastics material in such a way that, with a device that is of the simplest possible construction, secure positioning of the component to be encapsulated in the receptacle of the device is made possible. This object is achieved according to the invention in the case of a device for encapsulating a component with plastics material by the holding element (slide pin) holding the component in the region of the receptacle by interlocking or clamping engagement. In other words, this means that the component is arranged in operative connection with the holding element in such a way that secure holding or positioning of the component in the receptacle is made possible by the shaping of the (single) holding element alone. 
     In a particularly preferred structural configuration of the single holding element, it is proposed that the holding element has on the side facing the component a receiving region for encapsulating certain regions of the component. For example, the holding element may be formed for this purpose in a sleeve-shaped manner, while the component has a pin-shaped continuation, which protrudes into the sleeve-shaped receiving region. Appropriate dimensioning of the diameters of the receiving region and of the continuation on the component then allows the required clamping or interlocking engagement to be achieved. 
     In a further configuration, which makes a particularly compact construction of the tool and particularly good guidance of the holding element possible, it is proposed that the holding element is enclosed at least in certain regions by a tubular element (nozzle needle) serving for the inflow of the liquid plastics material into the receptacle. 
     The construction of the tool can be additionally made particularly simple if the holding element and the tubular element are arranged in one tool half, the tool half having at least one feeding region for the plastics material, in which the holding element and the tubular element are partially arranged. This allows the other tool half to be kept free of additional guides for the holding element or the tubular element for influencing the inflow of the liquid plastics material, so that it can be formed in a particularly simple manner. 
     A further structurally advantageous configuration concerns the region in which the liquefied plastics material enters the receptacle of the tool. It is proposed here that the injection channel is formed in one tool half, between the tubular element and the other tool half, the opening cross section of the injection channel being controllable by means of the position of the tubular element, and the plastics material flowing radially around the element in the region of the injection channel. 
     Most particularly preferred in this respect is a form of the tubular element in which it has on its outer wall a portion of reduced diameter for closing and opening the injection channel, it being particularly preferred for the portion to be formed as an annular groove. Such a form of the element brings about in particular a particularly good flow of the plastics material around the component to be encapsulated and, in addition, reduced loading of the connection between the holding element and the component, since the radial flow around the component does not allow the liquid plastics material to impinge directly on the end face of the component and thereby exert a releasing force on the connection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and on the basis of the drawing, in which: 
         FIGS. 1 to 5  show a first device according to the invention for encapsulating a component with plastics material during various phases of the encapsulation in respectively simplified longitudinal sections, 
         FIGS. 6 to 10  show a device modified with respect to  FIGS. 1 to 5 , likewise during various phases of the encapsulation of a component in simplified longitudinal sections and 
         FIG. 11  shows a detail of  FIG. 7  in an enlarged representation. 
     
    
    
     The same components or components with the same function are provided with the same reference numerals in the figures. 
     DETAILED DESCRIPTION 
     In  FIGS. 1 to 5 , a first device  10  according to the invention for encapsulating a component  1  with plastics material  2  is represented. The component  1  is, for example, but not in a restrictive sense, a sensor  4 , which has an electronic circuit  3  and can by way of example be electrically contacted by means of two electrical terminal lugs  5 ,  6 . It is intended here for the sensor  4  to be encapsulated with the plastics material  2  with the exception of in the region of the terminal lugs  5 ,  6 . 
     The device  10  has two tool halves  11 ,  12 , which are movable with respect to one another in the direction of the double-headed arrow  13  by means of a drive that is not represented. A fundamental distinction is drawn here between two positions of the two tool halves  11 ,  12 : in one position, represented in  FIG. 5 , the sensor  4  can be introduced into the device  10  before the encapsulation and removed from the device  10  after the encapsulation, while in the closed position of the two tool halves  11 ,  12 , represented in  FIGS. 1 to 4 , there is formed a receptacle  15 , which can be filled with the injected plastics material  2  for encapsulating the sensor  4  and for forming the outer contour of the encapsulated sensor  4 . 
     The one tool half  11  is for example formed in an L-shaped manner in longitudinal section, with a substantially annularly formed first feeding region  16  for liquefied plastics material  2  and a second feeding region  17 , which is arranged at right angles to the feeding region  16  and via which the liquefied plastics material  2  passes into the first feeding region  16 . The first feeding region  16  or the tool half  11  has on the side facing the tool half  12  a wall portion  18  that is withdrawn in the form of a flange and has a through-opening  19 . In line with the through-opening  19 , a further through-opening  21  is formed on the side of the first feeding region  16  that is facing away from the wall portion  18 . The two through-openings  19 ,  21  serve for guiding a slide pin  22 , formed as a holding element, and a nozzle needle  23 , which are arranged coaxially in relation to one another, and which are movable independently of one another in the direction of the double-headed arrow  24 , for example by means of actuating flanges  25 ,  26  arranged outside the tool half  11 . Here, at least the nozzle needle  23  is guided in the further through-opening  21  such that it is sealed at its outer circumference. 
     The two actuating flanges  25 ,  26  are preferably coupled to drives that are not represented, which make a controlled movement of the nozzle needle  23  and of the slide pin  22  possible. 
     The slide pin  22  has on the side facing away from the actuating flange  25  a holding receptacle  28 , which in the exemplary embodiment represented is formed as a cylindrical holding receptacle  28 . The holding receptacle  28  interacts with a pin-shaped continuation  7 , which is formed on the component  1  on the side facing the holding receptacle  28 , for the positioning and holding of the component  1  in the receptacle  15 . It is essential here that the dimensioning of the continuation  7  and of the holding receptacle  28  are made to match one another in such a way that, for the holding or positioning of the component  1  during the encapsulation of the component  1  with plastics material  2 , an interlocking or clamping engagement is established between the holding receptacle  28  and the continuation  7  or the component  1 , making it possible for the component  1  to be held or positioned in the receptacle  15  during the encapsulation of the component  1  with liquid plastics material  2 . 
     It is additionally mentioned that the form of the holding receptacle  28  and of the continuation  7  is intended to be represented merely by way of example and the respective form thereof must be adapted to the respective component  1  or the application in such a way that an interlocking or clamping engagement is established between the holding receptacle  28  and the continuation  7 . 
     The sliding pin  22  is arranged such that it is substantially adjustable between two positions within the tool half  11 : in the position represented in  FIGS. 1 and 2 , the holding receptacle  28  protrudes into the tool half  12  or the receptacle  15  and securely holds the component  1  in the position intended for it within the receptacle  15 . On the other hand, the slide pin  22  is in a position located in the region of the through-opening  19  for the complete encapsulation of the component  1  with the plastics material  2 , as is represented in  FIGS. 3 and 4 . 
     The nozzle needle  23  is formed in a substantially tubular manner and encloses the slide pin  22  at the outer circumference thereof almost without any gap, in such a way that the slide pin  22  is longitudinally displaceable in relation to the nozzle needle  23 . The nozzle needle  23  also has substantially two positions: in the one position, represented in  FIGS. 1 and 4 , the side of the nozzle needle  23  facing away from the actuating flange  26  finishes flush with the outer end face  29  of the wall portion  18 . On the other hand, the nozzle needle  23  is in a position retracted into the first feeding region  16  for delivering the liquefied plastics material  2  via an annular channel  30  formed between the slide pin  22  and the through-bore  19 , as is represented in  FIGS. 2 and 3 . 
     It may preferably be provided that the tool half  11  has in the region of the wall portion  18  a heating device  31 , for example in the form of a heating wire, surrounding the through-opening  19  at a small distance, in order that it is ensured that the plastics material  2  is in the liquefied state when it is injected into the receptacle  15 . 
     The second tool half  12  is formed in a substantially pot-shaped manner, in such a way that, in the position of the tool half  12  arranged in operative connection with the tool half  11 , the annular end face  32  thereof finishes flush with the end face  29  of the tool half  11 . On the side facing away from the end face  32 , the tool half  12  has in its interior a pin-shaped continuation  33  with two receiving openings  34 ,  35 , which serve for receiving the two terminal lugs  5 ,  6  of the component  1  in a sealing manner. In this case, the form of the receiving openings  34 ,  35  is, however, such that they do not serve for the positioning of the component  1  in the receptacle  15 , but merely for the sealing of the terminal lugs  5 ,  6 , in order that they are not encapsulated by the plastics material  2 . Between the continuation  33  and the inner wall of the tool half  12 , the receptacle  15  forms an annular subregion  36 . 
     The device  10  described thus far for encapsulating the component  1  with plastics material  2  operates as follows: in the position of the device  10  represented in  FIG. 1 , the component  1  has already been positioned in advance with its terminal lugs  5 ,  6  in the receiving openings  34 ,  35  of the tool half  12  and the slide pin  22  has been brought with its holding receptacle  28  into operative connection with the continuation  7  of the component  1 . Furthermore, the tool half  12  is in its position moved up against the tool half  11 , in such a way that the outwardly sealed receptacle  15  is formed by the end face  32  of the tool half  11  and the interior space of the tool half  12 . In the position represented in  FIG. 1 , it is already preferably provided that liquefied or heated plastics material  2  is in the feeding regions  16 ,  17  of the tool half  11 . For this purpose, the nozzle needle  23  is in its position closing the through-opening  19  or the channel  30 , in order initially to prevent injection of plastics material  2  into the receptacle  15 . 
     Subsequently, in a way corresponding to  FIG. 2 , the nozzle needle  23  is moved into its position retracted into the receptacle  15 , in such a way that plastics material  2  can pass via the annular channel  30  into the receptacle  15 . As soon as the receptacle  15  is completely filled with plastics material  2 , the nozzle needle  23  is moved back into its position protruding into the receptacle  15  or the through-opening  19 , so that the region of the continuation  7  can also be encapsulated with the plastics material  2 . Subsequently, in a way corresponding to  FIG. 4 , the nozzle needle  23  is moved again into its position closing the annular channel  30 , in order that the receptacle  15  is separated from the first feeding region  16 , so that the plastics material  2  enclosing the component  1  in the receptacle  15  can cool down. 
     Finally, in a way corresponding to  FIG. 5 , the tool half  12  is moved away from the tool half  11 , so that the component  1  encapsulated with plastics material  2  can be demolded or removed from the tool half  12 . 
     In  FIGS. 6 to 11 , a second device  10   a  according to the invention is represented. The device  10   a  differs from the device  10  by the form of the nozzle needle  23   a . Here, the nozzle needle  23   a  has on the side facing away from the actuating flange  26  a portion of reduced diameter in the form of a radially peripheral annular groove  40 . As can be seen in particular from  FIG. 11 , by contrast with the device  10 , for injecting the plastics material  2  into the receptacle  15 , the nozzle needle  23   a  is moved into a position in which the annular groove  40  is in the region of the annular channel  30 , in such a way that the end  41  of the nozzle needle  23   a  is positioned axially in relation to the component  1  such that plastics material  2  flowing via the remaining annular channel  30  between the nozzle needle  23   a  and the through-opening  19  into the receptacle  15  is deflected radially outward in such a way that it does not impinge directly on the end face  8  of the component  1  and cannot produce a force there on the component  1  that releases it from the holding receptacle  28 . 
     The devices  10 ,  10   a  described thus far can be changed or modified in various ways without departing from the concept of the invention. It is conceivable in particular that the device  10 ,  10   a  consists of more than two tool halves  11 ,  12 . In addition, it is also conceivable that components  1  that do not have terminal lugs  5 ,  6  are encapsulated with plastics material  2 . It may also be provided that, before the retraction of the slide pin  22  from the component  1  in a way corresponding to  FIG. 4 , the plastics material  2  located in the receptacle  15  has partially set, in order to ensure when the slide pin  22  is retracted that the slide pin  22  comes away from the component  1  without the component  1  being displaced from its position in the receptacle  15 .