Abstract:
The invention pertains to a device for acquiring signals from sensors ( 1 ) installed in a motor vehicle, where at least two sensors, which are connected by electrical conductors to a source of electrical voltage ( 2 ) and to an evaluation unit ( 3 ), are mounted in different positions in the vehicle. To simplify the installation of the device, the sensors ( 1 ) are attached a certain distance apart to a common ribbon cable ( 4 ) with parallel electrical conductors, which cable has at least one conductor which can be connected to the voltage source ( 2 ) to supply power to the sensors ( 1 ) and several signal conductors, which can be connected to the evaluation unit ( 3 ) and possibly also to the voltage source ( 2 ), the number of which corresponds to the number of sensors to be connected. All of the sensors ( 1 ) are connected to the power-supply conductor, and each one is connected individually to one of the signal conductors.

Description:
RELATED APPLICATION 
     This application is related to and claims the benefit of priority from German Patent Application No. 103 44 464.5, filed on Sep. 25, 2003, the entirety of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention pertains to a device for acquiring signals from sensors installed in a motor vehicle, where at least two sensors, which are connected by electrical conductors to a source of electrical voltage and to an evaluation unit, are mounted in different positions in the vehicle. 
     BACKGROUND 
     A device of this type can be mounted in different areas of a motor vehicle and can also serve different purposes. For example, temperature sensors, which are installed at various points in the interior of the vehicle, can be used to control the vehicle&#39;s climate-control system. The sensors could also be of the distance-measuring type, which are installed in the area of the vehicle&#39;s bumpers. This particular application of the device will be considered in the following as a representative of all the other possible applications of such devices, but the invention is not to be considered restricted to this application. 
     A system for warning the vehicle&#39;s operator against an obstacle is referred to in engineering jargon as “park distance control”. It is used especially during the parking process and makes use of optical and/or acoustic signals to tell the operator how far the vehicle is from an obstacle. The vehicle driver can then stop his vehicle in time so that a collision with the obstacle is avoided. 
     Similar devices are already present in modern motor vehicles. The sensors used as distance-measuring devices are usually positioned in the vehicles&#39; bumpers. Each sensor is connected by electrical conductors to the voltage source (the battery) of the vehicle and by a signal conductor to the vehicle&#39;s signaling device. The corresponding conductors are usually combined into so-called cable harnesses. The larger the number of sensors, the thicker the cable harness and the greater the complexity of the work required to install the sensors. 
     OBJECTS AND SUMMARY 
     The invention is based on the task of simplifying the device described above with respect to its design and handling. 
     This task is accomplished according to the invention in that:
         the sensors are connected to each other a certain distance apart on a common ribbon cable with parallel electrical conductors, which cable has:   at least one conductor which can be connected to the voltage source to supply power to the sensors and   several signal conductors, which can be connected to the evaluation unit and possibly also to the voltage source, the number of which corresponds to the number of sensors to be connected; and in that   all of the sensors are connected to the power-supply conductor, and each one is connected individually to one of the signal conductors.       

     A ribbon cable of predetermined length can be equipped with the desired number sensors for this device right in the factory. In this completely prefabricated form, it can be installed in the area of, for example, the bumper of the motor vehicle or in the bumper itself and connected electrically to the voltage source and to the evaluation unit of the motor vehicle. An appropriate connecting cable can also be connected to the ribbon cable right in the factory. After the installation of this device, the sensors are already in their intended positions in the motor vehicle. To connect it to the voltage source and to the evaluation unit, only a single connecting cable is required per device, the number of conductors in the connecting cable corresponding to number of the conductors in the ribbon cable. The device is easy to install, because in each case only one prefabricated component must be installed in the vehicle and fastened in place. It is simple in its overall design and has only a few individual parts. 
     In a preferred embodiment, the sensors are not connected directly to the ribbon cable but rather by way of plug-and-socket connectors. For this purpose, plug elements with contacts can be attached in a waterproof manner to the points along the length of the ribbon cable where the sensors are to be connected; the sensors, which are equipped with appropriately designed mating contacts, can then be set onto the plug elements. It is advantageous for this to be done during or after the installation of the ribbon cable in the vehicle. 
     It is especially advantageous for the plug elements installed on the ribbon cable to be of identical design for all the sensors and for these plug elements to have the same number of contact blades as there are conductors in the ribbon cable. In each plug element, only one of the several contact blades provided for the signal conductors will actually be in effective contact with one of the signal conductors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the object of the invention are illustrated in the drawings: 
         FIG. 1  shows a schematic diagram of a device with sensors according to the invention; 
         FIG. 2  shows a magnified view, also in the form of a schematic diagram, of the arrangement of the sensors according to  FIG. 1 ; 
         FIG. 3  shows a part of the device according to  FIG. 1  on an even larger scale; 
         FIG. 4  shows a cross section through  FIG. 3  in the direction of line IV-IV; 
         FIGS. 5-8  show parts of the device according to  FIG. 1  in embodiments different from that shown in  FIG. 3 , also on an enlarged scale; and 
         FIGS. 9 and 10  show two different views of a pin which can be used in the device. 
     
    
    
     DETAILED DESCRIPTION 
     In the exemplary embodiment illustrated in  FIG. 1 , four sensors  1  are present in a device according to the invention. The device can also be equipped with more or fewer than four sensors  1 . It should have at least two sensors  1 . The sensors  1  are connected to an electrical voltage source  2 , which supplies them with power, and also to an evaluation unit  3 , referred to in the following as the “signaling unit  3 ”, both of which are installed in a vehicle, also referred to as a “car” or “passenger car” in the following. The voltage source  2  will usually be the car battery. When the car approaches an obstacle, the signaling unit  3  transmits optical and/or acoustic warning signals, so that the driver can stop his car in time. This is advantageous especially when the driver is parking the car in an empty parking space. Sensors  1  will therefore always be installed at the rear of the vehicle, preferably on the bumper present there. 
     In the device according to the invention, the sensors  1  are connected to the electrical conductors of a ribbon cable  4 , as shown in  FIGS. 1 and 2 . The ribbon cable  4 , referred to in the following as “RC  4 ”, is preferably designed as a ribbon cable in which flat conductors with a rectangular cross section are embedded in insulating material parallel to each other but a certain distance apart. The conductors can for this purpose be laminated between two sheets of insulating material. The insulating material could also be extruded around the conductors, however. A cable of this type takes of up little space and is also quite flexible. 
     In the exemplary embodiment illustrated here, RC  4  has six electrical conductors  5 - 10 . The conductors  5  and  6  serve to supply power to the sensors  1 , all of which are connected to these two conductors. The other four conductors are signal conductors  7 ,  8 ,  9 , and  10  for transmitting the signals (data) supplied by the sensors  1  to the signaling unit  3 . For this purpose, as shown in  FIG. 2 , each sensor  1  is connected to one of the signal conductors  7 - 10 , so that the data from an individual sensor  1  are transmitted to the signaling unit  3  separately from the data of the other sensors. 
     A connecting cable  11  is connected to RC  4 . In the present exemplary embodiment, this cable, like RC  4 , has six conductors and serves to connect the sensors  1  to the voltage source  2  and to the signaling unit  3 . 
     In a preferred embodiment, a plug element  12  is attached as a first step in a waterproof manner to the RC  4  at every point where a sensor  1  is to be connected. As shown in  FIG. 3 , the plug element  12  has six contact blades  13 ,  14 ,  15 ,  16 ,  17 , and  18 . It also has three pins  19 ,  20 , and  21 , upon which a sensor  1  equipped with appropriately designed mating contacts can be set. It is especially advantageous for all of the connection points to be equipped with plug elements  12  of identical design. The contact blades and pins are mounted in a common holder  22  of stable insulating material, which is itself mounted in a frame  23 , which surrounds the RC  4  in a waterproof manner. 
     By way of example, the following procedure can be used to install a plug element  12  according to  FIG. 3  and to establish the electrical connection between its contact blades  13 - 18  and the conductors  5 - 10  of the RC  4 : 
     At a connection point provided for a plug element  12 , a strip of insulation of predetermined width extending across RC  4  is removed from the RC  4  above the conductors  5 - 10  on at least one side. The frame  23  of the plug element  12 , consisting preferably of sealing material, is then attached to the RC  4  in such a way that the uninsulated part of the strip remains exposed. Then, the holder  22  is set into the frame  23  in such a way that the ends of the contact blades  13 - 18  rest against the now bare parts of the associated conductors  5 - 10  of the RC  4 . Previously, three of the contact blades  15 - 18  have been interrupted or disconnected by means of a stamping operation, for example, because the pin  21  serving to connect the sensor  1  to the signaling unit  3  is originally connected to all four contact blades  15 - 18 , which are also connected to each other. Per connection point, three of the contact blades  15 - 18  are therefore interrupted. According to  FIG. 3 , this interruption applies to the contact blades  15 ,  17 , and  18 . Contact blade  16  is not interrupted, which means that the pin  21  is connected via the contact blade  16  and the signal conductor  8  to the signaling unit  3 . 
     All of the contact blades  13 - 18  are then connected electrically to their intended conductors of the RC  4 , preferably by welding or soldering. This is done preferably in a uniform manner in a single procedure for each connection point. As a result, according to  FIG. 3 , the contact blades  13  and  14 , which are separate from each other, are connected to the power-supply conductors  5  and  6 , and simultaneously the contact blade  16  is connected to the conductor  8  of the RC  4 . This also applies to the pins  19  and  20 , which are attached to the contact blades  13  and  14 , and to the pin  21 , which is connected to the contact blade  16 . By means of an injection-molding process, for example, the plug element  12  can then be embedded in a waterproof manner in a protective body  24  of insulating material in such a way that the free ends of the pins  19 ,  20 , and  21  are left exposed. A sensor  1  can be set down onto the pins  19 ,  20 , and  21 , which are projecting out from the protective body. The connection point in question, however, can also be covered in a waterproof manner by, for example, a cover attached to the frame  23 . 
     An embodiment of the device different from that of  FIG. 3  with differently designed connection points for the sensors  1  can be seen in  FIGS. 5-8 . Here, three pins  25 ,  26 , and  27  of identical design are used per connection point. As illustrated in  FIGS. 9 and 10 , they have the form of an “L” with a shorter sidepiece  28  and a longer sidepiece S, which serves as the actual pin. This pin part is crosshatched in  FIG. 10  and in  FIGS. 5-8 . A piercing element  29  (illustrated only in schematic fashion) is provided on the bottom surface of the shorter sidepiece  28  of the pin to make contact with a conductor of the RC  4 . The pins  25 ,  26 , and  27  are thus each electrically connected to one of the conductors  5 - 10  of the RC  4 , whereas the ends of their longer sidepieces S, which project vertically from the RC  4 , serve to accept the sensors  1 . The ends of the pins  25 ,  26 , and  27 , which are equal distances apart, preferably form the vertices of a triangle at each connection point. The shorter sidepieces  28  of the pins  25 ,  26 , and  27  should not be wider than the conductors of the RC  4  onto which they are placed and with which they establish electrical contact. 
     In the embodiment of the device according to  FIGS. 5-8 , the power-supply conductors  5  and  6  of the RC  4  are in the middle of the RC  4 . Two of the signal conductors  7 - 10  are on one side of the conductors  5  and  6 , and the two others are on the other side. The three pins  25 ,  26 ,  27  are arranged differently at each of the four connection points, because different signal conductors must be contacted. To establish the electrical connections with the conductors  5 - 10  of the RC  4 , the piercing elements  29 , as already mentioned, are preferably provided on the short sidepieces  28  of the L-shaped pins  25 ,  26 , and  27 ; the piercing element  29  pierces the insulation of the RC  4  and the associated conductor and is thus connected permanently to it. The pins and conductors, however, can also be connected to each other by welding or soldering, after the conductors have first been freed of their insulation at the appropriate points. So that all four signal conductors  7 - 10  can be contacted without changing the triangular arrangement of the pins  25 ,  26 ,  27 , the sidepieces  28  of the pins to be connected to the signal conductors at the various connection points need only to be rotated 90°. This applies to the two signal conductors  7  and  8  on one side and also to the signal conductors  9  and  10  on the other. 
     At the connection point for a sensor  1  according to  FIG. 5 , the pin  25  is connected to the conductor  5  of the RC  4  which serves to supply power. Its short sidepiece extends in the direction of the conductor  5 . The short sidepiece of pin  26 , however, is at a right angle to the conductor  6 , to which it is to be connected. This also applies to the pin  27 , which is connected to the signal conductor  10 . The connection points between the short sidepieces  28  of the pins and the conductors of the RC  4  are indicated by “X&#39;s” in  FIGS. 5-8 . 
     At the connection point shown in  FIG. 6 , the positions of the pins  25  and  26  are the same as those shown in  FIG. 5 . To connect a sensor  1  to the signal conductor  9 , however, the pin  27  has been rotated 90° from the position shown in  FIG. 5 . The short sidepiece of the pin  27  now extends in the direction of the signal conductor  9 , to which it is electrically connected. 
       FIGS. 7 and 8  show similar combinations of power-supply conductors  5  and  6  and signal conductors, except that here it is signal conductors  7  and  8  which are to be contacted. The two pins  25  and  26  are rotated in comparison with their positions in the connection points shown in  FIGS. 5 and 6 . In the present combinations with the signal conductors  7  and  8 , however, they are still connected to the conductors  5  and  6  of the RC  4  serving to supply power. The pin  25  is now connected to the power-supply conductor  6  with its shorter sidepiece extending in the direction of the conductor  6 . The shorter sidepiece of the pin  26  is now at a right angle to the conductor  5 , to which it is electrically connected. In the first of the two connection points in which the signal conductors  7  and  8  on the other side of the RC 4  are to be contacted, as shown in  FIG. 7 , the pin  27  establishes contact with the signal conductor  7  with its short sidepiece forming a right angle with the conductor  7 . For the fourth connection point according to  FIG. 8 , the pin  27  is rotated 90° versus  FIG. 7 . Its short sidepiece here extends in the direction of conductor  8 , to which it is connected. 
     To stabilize them, if desired, the pins  25 ,  26 ,  27  at all of the connection points can also be embedded by injection molding in a waterproof protective body so that their free ends are left exposed, as described further above in association with the embodiment of the device according to  FIGS. 3 and 4 . The sensors  1  can then be set onto the pins  25 ,  26 ,  27  projecting from the protective body. In this embodiment, too, there is also the alternative of sealing off the connection points by means of a waterproof cover. 
     The device according to the invention has been described above on the basis of its use in a park control system for passenger cars. When the device is to be used, for example, as part of temperature detection unit in the climate-control system of a passenger car, the sensors can be designed as temperature-dependent electrical resistors, for example, to detect the temperature. The RC  4  then requires only one power-supplying “go” conductor, which is connected to the voltage source and to which all of the temperature sensors are connected. The conductors referred to above as signal conductors are used as the power return lines, to each of which one of the temperature sensors is connected independently of the others. The temperature-dependent resistance value to be evaluated as the signal in this application is thus easily transmitted and evaluated.