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CROSS REFERENCE TO A RELATED APPLICATION 
     This application is a continuation of and commonly assigned U.S. Pat. application Ser. No. 09/936,798, filed Sep. 12, 2001 now U.S. Pat. No. 6,619,832 B1 and entitled “Poker Vibrator with Frequency Transformer”, the subject matter of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention pertains to a poker vibrator. 
     Poker vibrators of this type are used to compress fresh concrete by attaching a vibrator body or housing to a protective tube. The vibrator body contains an eccentric weight rotated by an electric motor. In order to produce a compression frequency suitable for the fresh concrete, the motor must rotate with a very high rate of rotation, for example 12,000 RPM. This requires a higher electrical frequency compared to normal commercial power frequencies. To produce the increased electrical frequency, a frequency transformer is connected upstream of the electric motor, increasing the commercial power frequency from 50 Hertz to, for example, 200 Hertz. 
     There are poker vibrators wherein the protective tube is designed as an operating tube at the same time, having a length of a few meters. A switch housing is attached to the end of the protective tube opposite the vibrator housing. This switch housing contains a line switch. An electric cable runs from the switch housing to a plug that can be inserted into a conventional frequency transformer. The disadvantages in operating a poker vibrator of this kind, which are a consequence of the separate frequency transformer that is very cumbersome and difficult to handle, have resulted in the development of a poker vibrator that combines the frequency transformer with the switch in a miniaturized switch housing. This type of poker vibrator is described in EP 0 604 723 and has proven itself to be outstanding in practice. In particular, the device is very easy to operate since there is no longer a separate frequency transformer. 
     However, in order to integrate the frequency transformer into the switch housing, it was necessary to make the switch housing somewhat larger, which can be a disadvantage in pulling it around and with its portability at the construction site. In particular, it is possible for the somewhat enlarged switch housing to get caught on concrete reinforcement bars. Also, the switch housing with the integrated frequency transformer has a considerable weight so that constantly pulling the switch housing around can be difficult during work. 
     U.S. Pat. No. 5,202,612 portrays a poker vibrator that has an electric motor in a vibrator housing that is provided a power current through an electric power feed system. This current has an electrical frequency that deviates from the commercial power frequency. In the cable constituting the electric power feed system, there is first of all a switch and secondly a frequency transformer separately located from the switch. 
     In GB-A-2 279 184, a power plug is described with an integrated switch to interrupt the current feed. 
     DE 197 22 107 portrays a cable drum with an integrated frequency transformer. A power plug from a poker vibrator that requires a frequency produced from the frequency transformer can be inserted into an outlet in the cable drum. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The objective of this invention is to provide a poker vibrator that is even easier to handle, whose portability in particular is improved and whose weight that has to be moved around by the user is reduced. 
     The solution to this objective is provided by the poker vibrator of the present invention. Advantageous developments and embodiments of the invention can also be found in the following description. 
     A poker vibrator is characterized in that at least some of the components of the frequency transformer are located inside the vibrator housing or the plug housing. There are essentially two concepts of this embodiment form: 
     All components of the frequency transformer are integrated into the vibrator housing; 
     All components of the frequency transformer are integrated into the plug housing; or 
     The components of the frequency transformer are built into different areas of the poker vibrator. 
     Numerous advantages arise from the above for the construction and operation of the poker vibrator. These will be explained in detail later in the description of the embodiment forms. The essential feature is that the frequency transformer is no longer integrated into the switch housing, resulting in the advantage that the housing is very light and “slippery”, or can be slid again due to its low weight and small dimensions. In operating the poker vibrator, this results in the advantage that the switch housing can be pulled from behind when working with the operating tube. 
     Secondly, the arrangement of the frequency transformer&#39;s components at certain points in the poker vibrator offers the ability to install the components at targeted locations where it is especially beneficial for them to be kept. Thus, it is especially advantageous if a power component that produces a lot of heat during operation is kept in the vibrator housing that is dipped into the wet concrete, since in this way an especially effective cooling is possible. 
     It is not necessary that the invention variations have the switch located in its own switch housing. The switch can also be integrated into the plug housing, into the protective tube or into the vibrator housing. 
     The poker vibrator of the present invention also defines an embodiment form in which the frequency transformer and the switch are kept in different housings, namely in this case in a coupling and in a switch housing, respectively. This makes it possible to optimize the weight distribution at the poker vibrator and allows a shape for better portability. This can be done in a way that integrates the switch into the plug housing, whereas the frequency transformer is located in the coupling between the protective tube and the electric cable. 
     In another variation of the invention at least some of the components of the frequency transformer are located in a transformer housing provided between the switch housing and the power plug. This also makes it possible to optimize the weight distribution and external shape of the poker vibrator. 
     The invention also contemplates still another embodiment form in which at least some of the components of the frequency transformer are located in the protective tube and this portion of the components is not integrated into the switch housing. This makes it possible, for example for a poker vibrator from EP 0 604 723, to remove at least some of the components of the frequency transformer from the switch housing described there and to locate them at other points in the protective tube. This makes it possible for the switch housing to be shaped like a streamline, resulting in the improvement of the poker vibrator&#39;s sliding ability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This and other advantages and features are explained in more detail below with the help of examples and with the aid of the accompanying drawing figures. 
     The first figure shows a poker vibrator according to the invention in a perspective view. 
     The second figure shows a second embodiment of the poker vibrator in a perspective view. 
     The third figure shows a third embodiment of the poker vibrator in a perspective view. 
     The fourth figure shows a fourth embodiment of the poker vibrator in a perspective view. 
     The fifth figure shows a fifth embodiment of the poker vibrator in a perspective view. 
     The sixth figure shows a sixth embodiment of the poker vibrator in a perspective view. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In a vibrator housing  1 , also called a vibrator flask, is an electric motor  10 . This motor  10  drives an eccentric weight that rotates with a high rotational rate, serving as an oscillation-producing unit  12 . The sets the vibrator housing  1 , which is dipped into the still fluid concrete, into oscillatory motion, through which the desired compression effect is attained in the concrete. 
     The vibrator housing  1  is fastened to one side of a protective tube  2  that can be up to a number of meters (for example 6 meters) in length and can be held by the user during operation. Thus, the protective tube  2  can also be used as an operating tube. 
     A switch housing  3 , also called the switchgear, is attached to the other end of the protective tube  2  and is used here as a coupling. The protective tube  2  therefore extends linearly from the vibratory housing  1  to the switch housing  3 . This switch housing contains a switch  4 . Electrical feed lines  5  to the electric motor  10  in the vibrator housing  1  can be connected or disconnected by means of the switch  4  in a known fashion. The electrical feed lines  5  run inside the protective tube  2 . 
     A rubber grommet  6  extends from the other side of the switch housing  3 . An electric cable  7  runs inside of it that terminates at a plug housing  9  with a plug  8 . The function of the coupling (here: switch housing  3 ) is to couple the stable protective tube  2  to the electric cable  7 . 
     As already explained, the electric motor  10  must rotate with very high revolutions and thus requires an electrical frequency to operate that is larger than the commercial power frequency. Common frequencies applied are in the 200-Hertz range, which corresponds to four times the commercial power frequency. 
     In order to attain the desired frequency, a process is known from the state of the technology to convert the supply current in a frequency transformer  14 . It was first of all possible to attain this by inserting the plug  8  into a separate frequency transformer unit  14 . Secondly, it is known that the switch housing  3  had to be enlarged in order to make space for the frequency transformer  14  next to the switch  4  there. Both embodiments have disadvantages, however, which are solved by this invention. 
     In a first embodiment form of the poker vibrator according to this invention and shown in FIG. 1, all components of the electronic hybrid frequency transformer  14  are integrated into the vibrator housing  1  and directly attached to the electric motor  10 . The supply current is fed from the plug  8 , through the electric cable  7 , the switch  4  and the electric feed lines  5  to the vibrator housing  1 . The electric cable  7  and the electric feed lines  5  form an electric feed from the plug  8  to the electric motor  10 . 
     This embodiment form has the advantage in that the switch housing  3  assumes a very small, handy and portable form so that the operator can easily move it around the rebar when operating the poker vibrator. Moreover, the cooling element volume of the electronic frequency transformer  14  can be reduced greatly, since the vibrator housing  1  made of metal dissipates heat from the frequency transformer  14  and conveys it to the wet concrete, which guarantees very efficient cooling. Moreover, the protective tube  2  no longer has to be shielded since it only feeds supply current. Finally, the winding temperature of the motor  10  can be measured using a temperature sensor and read back as an operating parameter. By providing suitable controls, the frequency transformer  14  can be controlled according to this temperature. 
     In a second embodiment form of the invention shown in FIG. 2, the frequency transformer  14  is completely integrated into the plug housing  9  containing the plug  8 . 
     This variation requires an enlarged plug housing  9  compared to common plug housings, which, however, does not result in disadvantages for the operation of the poker vibrator since the plug  8  is usually inserted into a fixed cable drum or outlet. Thus, the operator only seldom has to lift and move the plug housing  9  with the integrated frequency transformer  14  when operating the poker vibrator. 
     The vibrator housing  1  and the switch housing  3  do not change in the process. Since now the increased frequency is already present beginning at the plug housing  9 , the electric cable  7  and the electric feed lines  5  have to be shielded inside the protective tube  2 . Since the frequency transformer  14  is cooled in the plug housing  9  essentially using air, this embodiment form is advantageously suitable for small poker vibrators with small power usage. 
     The integration of the frequency transformer  14  into the plug housing  9 —for example by integrating it with a leakage current protection switch (FI-DI switch) (not shown)—provides for an especially high operational safety. In addition, it is possible to monitor the vibrator housing  1  containing the electric motor  10 , the frequency transformer  14 , the protective tube  2  and the electric cable  7  for short circuits, grounding, and leakage current using suitable electronics at the frequency transformer  14 . This protects these components. If the protective tube  2  with the feed lines  5  or the electric cable  7  is damaged, the power feed to the poker vibrator is interrupted immediately. 
     In the third embodiment form of the invention shown in FIG. 3, the components of the frequency transformer  14  are distributed in the poker vibrator according to what is best suitable if the frequency transformer  14  consists of a number of components. This means that a power component  16  and a processor  18  in the frequency transformer  14  are built into the vibrator housing  1 , resulting in optimum cooling by the wet concrete and with the vibrator housing  1  serving as the cooling body. The frequency transformer&#39;s rectifier  20  and a switching power supply  22  are integrated into the plug housing  9 . Any required capacitors, in particular DC intermediate circuit capacitors, can be integrated into the poker vibrator&#39;s protective tube  2 . 
     This type of distributed design enables minimal volumes and thus minimal weight of the poker vibrator. The switch housing  3 , which as before only contains the switch  4 , remains small and portable. Through the cooling effect of the vibrator flask  1 , additional cooling element volumes can be eliminated. By producing the higher frequency in the vibrator housing  1  itself, the protective tube  2  and the electric cable  7  do not have to be shielded. 
     A fourth embodiment example of the invention, which is shown in FIG. 4, is characterized in that the frequency transformer  14  is located in the coupling  3  between the protective tube and the electric cable, but a separate secondary switch housing  24  containing the switch  4  is located separately from the coupling  3 . This variation makes possible numerous different configurations to optimize the weight distribution and portability. 
     In a fifth embodiment form of the invention, shown in FIG. 5, the fourth embodiment form is further developed such that the secondary switch housing  24  is integrated into the plug housing  9 . 
     A sixth embodiment form, which is shown in FIG. 6, is characterized in that at least some of the components of the frequency transformer  14  are located in a transformer housing  28  provided between the switch housing  3  and the power plug  8 . This is another way to spatially separate the frequency transformer  14  and the switch housing  3  from one another so as to obtain the advantageous configurational possibilities. 
     The variations described are also suitable for poker vibrators with short protective tubes, for example a rod or wand-type vibrator. In these types of vibrators, the operation is not done using the protective tube, but by means of a hand grip  26  that for example is combined with the secondary switch housing  24  as shown in FIG.  4 . 
     Other possible variations for the application of the invention are the integration of the switch into the protective tube. Likewise, the coupling fastened to the end of the protective tube  2  can be eliminated if a switch or a frequency transformer does not have to be kept there. Instead, the end of the protective tube  2  can feed out through a grommet that is similar to rubber grommet  6  and can flow into the electric cable  7 . Likewise, it is possible to vulcanize the end of the protective tube  2  such that it transitions into the electric cable  7 . By integrating both the switch and the frequency transformer into the plug housing  9 , the protective tube  2  or the vibrator housing  1  at the same time, a poker vibrator with smooth exterior contours without bulges can be created that exhibits excellent slip accordingly.

Summary:
The invention relates to a poker vibrator for compressing concrete. The poker vibrator comprises a vibrating housing that accommodates an unbalanced mass and an electromotor, an insulating plastic tube that links the vibrating housing to a switch cover, an electric cable that links the switch cover to a connector shell and that bears a power plug, and a frequency converter that supplies the current for the electromotor. The poker vibrator is characterized in that the switch is arranged separately from a coupling piece on the tube and not on the electric cable and/or in that at least some of the components of the frequency transformer are arranged in a transformer housing provided between the switch housing and the powerplug.