Patent Publication Number: US-2005125109-A1

Title: Sensor harness fixing structure

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      The entire disclosure of Japanese Patent Application No. 2003-384490 filed on Nov. 14, 2003, including specification, claims, drawings and summary, is incorporated herein by reference in its entirety.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to a fixing structure for a harness for sensors and, more specifically, a harness fixing structure preferred for sensors provided outside a vehicle.  
      2. Description of the Related Art  
      In recent years, various control devices have been provided in a vehicle from the viewpoints of safety and operability, and various sensors have been used accordingly. These sensors are disposed in various portions of the vehicle. For example, a small sensor as a single unit may be configured such that the sensor and a harness are held integrally by a member such as resin. Such a configuration can serve as a waterproof structure capable of supporting the harness (Japanese Patent Application Laid-Open No. 2001-343292, pages 3-4, FIGS. 1 to 6). This structure can be provided not only inside the vehicle, but also in an engine portion subjected to high temperatures, and on the exterior of the vehicle exposed to rain, etc.  
      Among sensors used in control devices, there are those which are used as single units, such as temperature sensors, and those which are used as combinations of transmitters and receivers, such as ultrasonic sensors. With a sensor which uses a plurality of instruments (hereinafter referred to as a sensor unit), it is common practice to hold each of the instruments in a single case, integrate lead wires from the respective instruments into a harness, and perform the supply of power and the outputting of a detected signal with the use of the harness. If the sensor unit is provided outside the vehicle, the influence of the surroundings of the vehicle, i.e., the influence of rain, etc., has to be considered. Unless the use of an appropriate fixing structure for the harness is considered, water may enter the interior of the case via the harness. If the sensor unit is provided below the vehicle, in particular, consideration has to be given to the influence of water splashing up from the road surface.  
      Furthermore, if the sensor unit is provided outside the vehicle, the sensor, etc. are often stained, and need cleaning at appropriate times. During washing with water or the like, care should be taken to prevent entry of water into the case via the harness.  
      The present invention has been accomplished in the light of the above-mentioned problems. It is an object of the present invention to provide a sensor harness fixing structure which fixes the harness reliably and has high waterproofing properties.  
     SUMMARY OF THE INVENTION  
      According to a first aspect of the present invention, for solving the above-mentioned problems, there is provided a sensor harness fixing structure, comprising: 
          a first case accommodating sensors in an interior thereof, and having a protrusion on an outer surface thereof; and     a second case having a notch to be fitted with the protrusion.        

      An opening of the first case, and an opening of the second case are opposed to each other, and the second case is placed and fitted outside the first case to constitute one case.  
      A curved portion is provided at the bottom of the notch of the second case, and another curved portion is provided in a portion of the protrusion of the first case which is opposed to the curved portion of the second case.  
      In fixing a harness for the sensors disposed inside the first case, the harness is interposed and held between the curved portion of the second case and the other curved portion of the first case. Thus, the harness for the sensors is interposed and held on the same plane, and is reliably fixed.  
      According to a second aspect of the present invention, the harness for the sensors may be interposed and held via an elastic material such as rubber. By covering and clamping the harness for the sensors by use of the elastic material such as rubber, the harness itself can be protected, and the clamped portion ensures tight contact.  
      According to a third aspect of the present invention, the elastic material may be a corrugated tube covering the harness, the corrugated tube may have projections and depressions formed on the surface thereof, and projections and depressions corresponding to the projections and depressions formed in the corrugated tube may be formed in the first case and the second case.  
      According to the present invention with the above-described aspects, the harness for the sensors provided outside the vehicle can be reliably fixed, and the entry of water into the sensors via the harness can be prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:  
       FIG. 1  is a schematic configuration drawing of a truck equipped with an optical axis adjusting apparatus for a vehicle headlamp;  
       FIG. 2  is a plan view of a frame of the truck shown in  FIG. 1 ;  
       FIG. 3  is a configuration drawing showing an embodiment of a sensor harness fixing structure according to the present invention;  
       FIG. 4  is a view showing the mounting of an incline sensor, as shown in  FIG. 3 , to a cross member;  
       FIG. 5  is a sectional view of the incline sensor and the cross member mounted together; and  
       FIG. 6  is a configuration drawing showing another embodiment of the sensor harness fixing structure according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Various sensors are provided outside a vehicle. In the present invention, a sensor unit composed of ultrasonic sensors used for adjusting the optical axis of a vehicle headlamp is taken as an example to explain an embodiment of a sensor harness fixing structure according to the present invention.  
      Embodiment 1:  
       FIG. 1  is a schematic configuration drawing of a truck equipped with an optical axis adjusting apparatus for a vehicle headlamp.  FIG. 2  is a plan view of a frame of the truck shown in  FIG. 1 .  
      As shown in  FIG. 1  and  FIG. 2 , a truck has a frame mainly composed of a set of (i.e., right and left) side frames  1 , and a plurality of cross members  2  assembled perpendicularly to the side frames  1 , and has a cab  3  and a cargo bed  4  mounted on this frame. Right and left headlamps  5  are mounted on both sides of the cross member  2  located in a front end portion of the vehicle. An incline sensor  6 , which serves as a sensor unit using a plurality of ultrasonic sensors, is disposed at a nearly middle portion of the cross member  2 . A detection signal from the incline sensor  6  is inputted into an ECU  7  as a control instrument, and the ECU  7  determines the inclined state of a front portion of the vehicle relative to a road surface R based on the detection signal of the incline sensor  6 .  
      The right and left headlamps  5  may be provided in the cab  3 , and the incline sensor  6  may be provided on side rails above a front axle  8 , or provided at an end portion of the vehicle which is other than the cross member  2  (for example, on the cab  3 ).  
       FIG. 3  is a configuration drawing showing an embodiment of a sensor harness fixing structure according to the present invention, and shows the configuration of the incline sensor  6  shown in  FIGS. 1 and 2 . A view showing the mounting of the incline sensor  6  to the cross member  2 , and a sectional view of the incline sensor  6  and the cross member  2  mounted together are offered as  FIG. 4  and  FIG. 5 , respectively.  
      As shown in  FIG. 3 , the sensor harness fixing structure according to the present invention is composed of a case  11  (first case) of a U-shaped cross section having a protrusion  11   a  on the outer surface thereof, and a case  12  (second case) of a nearly U-shaped cross section having a notch  12   a  to be fitted with the protrusion  11   a  of the case  11 . The opening of the case  11  and the opening of the case  12  are opposed to each other, the case  12  is placed on and fitted to the exterior of the case  11 , and screw-holding portions  13  of the case  11  are tightened against screw-receiving portions  14  of the case  12  by means of screws. By this procedure, one box-shaped case, which becomes a housing of the incline sensor  6 , is formed.  
      Inside the case  11 , ultrasonic sensors  9  and  10  are disposed. A cover  15 , which has openings in portions corresponding to transmitting and receiving surfaces of the ultrasonic sensors  9  and  10 , is provided on the transmitting and receiving surface side (the side where the case  12  is located) of the ultrasonic sensors  9  and  10  to form a sensor body portion. A curved portion  12   b  is provided at the bottom of the notch  12   a  of the case  12 . Another curved portion  11   b  is provided in a portion of the protrusion  11   a  of the case  11  which is opposed to the curved portion  12   b  of the case  12 . A harness  16  composed of lead wires of the ultrasonic sensors  9  and  10  is led out of the cases  11  and  12  through a gap formed by the curved portions  11   b  and  12   b , and is connected to the ECU  7  via a connector  17  to enter detected signals into the ECU  7 .  
      That is, the incline sensor  6  holds the ultrasonic sensors  9  and  10  inside the case  11  having the above-described structure, and interposes and holds the harness  16  from the ultrasonic sensors  9  and  10  between the curved portion  11   b  of the case  11  and the curved portion  12   b  of the case  12 , thereby keeping the harness  16  in a clamped state on the same plane, reliably fixing it, and ensuring intimate contact, leading to enhanced waterproofness.  
      Moreover, the harness  16  is kept clamped and held via an elastic material such as rubber and, concretely, the harness  16  is wrapped in a covering material, such as a rubber tube. By this measure, the harness  16  itself can be protected from a force exerted by the case  11  and the case  12 , and the clamped portion can be brought into more intimate contact to enhance waterproofness further. As the covering material, not only the rubber tube, but also a resin tube, PVC (polyvinyl chloride) tube, or a corrugated tube may be used.  
      In the incline sensor  6 , the transmitting and receiving surfaces of the ultrasonic sensors  9  and  10  need to be exposed to the road surface so that the ultrasonic sensors  9  and  10  can detect the road condition. For this purpose, the portions of the case  12 , where the transmitting and receiving surfaces of the ultrasonic sensors  9  and  10  are located, are opened to be capable of transmitting and receiving ultrasonic signals. These opening portions are also configured such that the sensor surfaces are positioned inwardly of the case  12 , so that foreign matter, water or the like will not penetrate inside through the opening portions.  
      The incline sensor  6 , as shown in  FIG. 4 , is attached to an intermediate portion of the cross member  2  by means of bolts  20   a  and nuts  20   b  through bolt holes  19  provided in a peripheral edge portion  18  of the case  12 , whereby the incline sensor  6  is attached to the front portion of the vehicle so as to be opposed to the road surface R. Moreover, the ultrasonic sensors  9  and  10  are housed in the cases  11  and  12 , whereby the incline sensor  6  itself can be rendered compact, and can be easily mounted onto the cross member  2 .  
      The configuration and actions of the ultrasonic sensors  9  and  10  constituting the incline sensor will be explained briefly. The two ultrasonic sensors  9  and  10  are composed of transmitters  9   a  and  10   a  as signal transmitting portions, and receivers  9   b  and  10   b  as signal receiving portions, for transmitting and receiving ultrasonic signals in the vehicle width direction of the vehicle. In detail, the transmitters  9   a  and  10   a  are disposed on one side (for example, right side) in the vehicle width direction, while the receivers  9   b  and  10   b  are disposed on the other side (for example, left side) in the vehicle width direction. The directions of ultrasonic waves transmitted and received by the ultrasonic sensors  9  and  10  are nearly parallel to each other, and are nearly perpendicular to the longitudinal direction of the vehicle.  
      The incline sensor  6  determines the inclined state of the vehicle relative to the road surface R based on a difference in receiving time between the ultrasonic waves transmitted and received by the two ultrasonic sensors  9  and  10 . Concretely, assume that when the ultrasonic signals from the transmitters  9   a  and  10  are reflected by the road surface R and received by the receivers  9   b  and  10   b , the front portion of the vehicle is inclined with respect to the road surface R. In this case, the heights at which the ultrasonic sensors  9  and  10  detect the ultrasonic signals are different. Thus, a difference occurs between the length of the path of the ultrasonic signal transmitted from the transmitter  9   a  to the receiver  9   b  and the length of the path of the ultrasonic signal transmitted from the transmitter  10   a  to the receiver  10   b . As a result, a receiving time difference arises between the receivers  9   b  and  10   b . Based on this receiving time difference between the receivers  9   b  and  10   b , the inclined state of the vehicle relative to the road surface R is determined by the ECU  7 .  
      Embodiment 2:  
      As another embodiment of the sensor harness fixing structure according to the present invention, an explanation will be offered for a structure in which the harness is covered with a corrugated tube.  
      As shown in  FIG. 6 , a harness  16  is covered with a corrugated tube  101  (elastic material) of a surface shape having projections and depressions, thereby making it possible to lower the possibility that the harness  16  and the corrugated tube  101  as the covering material will be damaged by a case  11  (first case) and a case  12  (second case). The projections and depressions on the surface of the corrugated tube  101  can also prevent the penetration of water more reliably.  
      Moreover, a surface  103  of the case  11  and a surface  111  of the case  12 , both surfaces opposed to the corrugated tube  101 , have a corrugated shape (projections and depressions) extending along the shape of the corrugated tube  101 , thereby forming a labyrinthine structure between the corrugated tube  101  and the surfaces  103 ,  111 , so that the penetration of water can be prevented more reliably.  
      Furthermore, a burr  105  may be produced on the end face (cut surface) of the corrugated tube  101 . In order that core wires  106  will not be damaged by the burr  105 , protective plates  104  are protruded from the cases  11  and  12  to keep the burr  105  and the core wires  106  out of contact with each other.  
      Besides, the harness  16  may be covered with a covering material such as a rubber tube, and further covered with the corrugated tube  101 .  
      While the present invention has been described by the foregoing embodiments, it is to be understood that the invention is not limited thereby, but may be varied in many other ways. For example, the ultrasonic sensor has been taken as an example for the purpose of explanation. However, the present invention is not limited to the ultrasonic sensor, but can be applied to various other sensors, such as a laser sensor, and a height sensor. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the appended claims.