Abstract:
A box-shaped electronic control unit for use in an automotive vehicle includes a pair of side stays for mounting the electronic control unit on a vehicle. The side stay integrally formed with a bottom cover is bent upward to form a bent portion. When electronic control units are carried by a conveyer, they are placed on a conveyer belt so that the bent portions face one another, thereby to avoid overlapping of the electronic control units on the conveyer belt. To form the side stay having a sufficient mechanical strength endurable against a high vibrating force of the vehicle, a pair of ribs extending from both sides of the bottom cover are formed on the side stays.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims benefit of priority of Japanese Patent Applications No. 2001-44884 filed on Feb. 21, 2001 and No. 2001-44885 filed on Feb. 21, 2001, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic control unit for use in an automotive vehicle, and more particularly to a casing containing the electronic control unit therein. 
     2. Description of Related Art 
     An electronic control unit (referred to as an ECU) for use in an automotive vehicle is composed of a case having a bottom opening, a bottom cover closing the bottom opening and a circuit board contained in an inner space formed by the case and the bottom cover. Side stays are provided at both sides of the bottom cover so that the ECU is mounted on an automotive vehicle via the side stays. 
     FIG. 7 shows a perspective view, components being separated, of a conventional ECU  50 . An ECU casing is composed of a case  51  and a bottom cover  53  closing a bottom opening of the case  51 . A circuit board  52  having electronic components thereon is contained in the casing. The case  51 , the bottom cover  53  and the circuit board  52  are connected together by common screws  54 . Side stays  55  having mounting holes  56  are provided at both sides of the bottom cover  53 . The ECU  50  may be directly mounted on a vehicle using the side stays  55 , or using a separate bracket connected to the side stays  55 . 
     In an automated line for mounting the ECU on the vehicle, plural ECUs  50  are placed on a conveyer passage  60  as shown in FIG. 8, and they are automatically picked up one by one by a robot arm or the like. When the ECUs  50  are positioned on the conveyer passage  60  in an upright posture (placing one sidewall on the conveyer belt  61 , as shown in FIG.  8 ), it is required to make a proper space between conveyer sidewalls  62  and the ECUs  50 . If the space is too large, the ECUs  50  fall on the conveyer belt  61 , or the ECUs are not correctly aligned on the conveyer passage  60 . On the other hand, if the space is too narrow, the ECUs  50  cannot be smoothly conveyed because sidewalls of the ECUs  50  contact the conveyer sidewalls  62 , resulting in a conveyer halt at the worst case. 
     Further, side stays  55  formed at both sides of one ECU  50  may overlap the side stays  55  of another ECU  50  when ECUs are consecutively conveyed with no space therebetween, as shown in FIG.  8 . If this happens, the ECUs  50  contact the conveyer sidewalls  62 , thereby being stopped in the conveyer passage  60 . The same problem may occur in a conveyer passage in which the ECUs  50  are conveyed in a flat posture. 
     Another problem in the conventional ECU resides in a mechanical strength of the side stays  55 . Since the side stays  55  of the conventional ECU  50  are formed by simply extending the bottom cover  53  in a flat shape, as shown in FIG. 7, its mechanical strength is not sufficiently high to endure high vibration of an automotive vehicle. When the ECU  50  is mounted on a portion where a high vibrating force is imposed, the side stays  55  may be broken. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an ECU which is smoothly carried by an automated conveyer system. Another object of the present invention is to provide an ECU which has mounting stays having a sufficient mechanical strength to endure a high vibrating force of an vehicle. 
     The ECU is substantially box-shaped and is composed of a case having a bottom opening, a bottom cover closing the bottom opening and a circuit board having electronic components mounted thereon contained in a space formed by the case and the bottom cover. The bottom cover includes a pair of side stays for mounting the ECU on an automotive vehicle. The side stays extend to both sides of the bottom cover, and each side stay includes a bent portion bent upward from a bottom plate of the bottom cover. 
     The ECUs are placed on a conveyer belt in a conveyer passage, taking an upright posture or a flat posture, so that the bent portion of one ECU directly faces the bent portion of another ECU. Since the bent portions abut one another when ECUs are conveyed in contact with each other, the side stays do not overlap one another. Therefore, the ECUs are smoothly carried by the conveyer without causing jam or halt in the conveyer passage. In most cases, the ECUs are placed on the conveyer belt in an upright posture. In this case, it important to make the height of the bent portion larger than a difference between the width of the conveyer passage and the height of the ECU to prevent overlapping of the ECUs in the conveyer passage. The maximum height of the bent portion may be limited not to exceed the height of fringe walls of the bottom cover, so that plural bottom covers can be stacked up in an assembly process of the ECU. 
     To enhance mechanical strength of the side stay, a first rib perpendicularly extending from the side of the bottom cover is formed on the side stay. The first rib is also utilized to connect the bottom cover to the case at a right position. In addition, a pair of second ribs are formed along both sides of the bottom cover. The second ribs are positioned inside the ECU when the bottom cover is connected to the case to prevent dusts or foreign particles from entering into the ECU. The bent portion of the side stay may be eliminated if it is not necessary, and only the first rib and/or the second rib may be formed to enhance the mechanical strength of the side stay, so that the side stay is able to endure a high vibrating force of an automotive vehicle. 
     Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an electronic control unit according to the present invention; 
     FIG. 2 is a perspective view showing components of the electronic control unit shown in FIG. 1, the components being separated from one another; 
     FIG. 3 is a top view showing electronic control units being carried on a conveyer belt; 
     FIG. 4 is a perspective view showing a posture of the electronic control units placed on the conveyer belt; 
     FIG. 5 is a side view showing bottom covers stacked up; 
     FIG. 6 is a cross-sectional view showing a case and a bottom cover of the electronic control unit, both connected to each other; 
     FIG. 7 is a perspective view showing components of a conventional electronic control unit, the components being separated from one another; and 
     FIG. 8 is a perspective view showing a posture of the conventional electronic control units being carried on a conveyer belt. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will be described with reference to the accompanying drawings. First referring to FIGS. 1 and 2, a structure of an ECU  10  will be described. A casing of the ECU is composed of a case  11  having a bottom opening and a bottom cover  14  closing the bottom opening of the case  11 . A circuit board  13  carrying a connector case  12  and electronic components thereon is contained in the casing. The case  11 , the circuit board  13  and the bottom cover  14  are connected together by screws  15  at four corners of the ECU  10 . The case  11  and the bottom cover  14  are made of a metallic plate such as an aluminum or a steel plate by presswork. For explanation purpose, four sides of the ECU  10  are denoted as front, rear, right and left sides, respectively, as shown in FIG.  1 . The connector case  12  is exposed to the front side of the ECU  10 . 
     The case  11  has a front opening  21   a  and three sidewalls  21   b ,  21   c ,  21   d . Of the three sidewalls, both sidewalls  21   b ,  21   c  at the left and right sides are slanted, while the sidewall  21   d  at the rear side stands upright. Fringe portions  22  are formed at the bottom ends of the sidewalls  21   b ,  21   c . Each fringe portion  22  includes a vertical wall  23  which is bent downwardly from a flat surface of the fringe portion  22 . A peripheral size of the bottom opening of the case  11  defined by both vertical walls  23  is a little larger than a peripheral size of the circuit board  13 . Flat cylindrical nuts  24  are embedded on the fringe portions  22  at the four corners. 
     The bottom cover  14  for closing the bottom opening of the case  11  is formed to have the same peripheral size as that of the circuit board  13 . The bottom cover  14  includes a bottom plate  31  and a pair of fringe walls  32 . The fringe wall  32  is upwardly bent from the bottom plate  31 , so that it has a certain height to accommodate the electronic components mounted on the circuit board  13 . The circuit board  13  is sandwiched between the fringe portions  22  of the case  11  and the fringe walls  32  of the bottom cover  14  when they are assembled. 
     The bottom cover  14  also includes a pair of side stays  33  extending to left and right sides thereof. Mounting holes  34  are provided on the side stays  33 . The ECU  10  is mounted on the vehicle via separate brackets connected to the side stays  33 . The separate brackets can be variously designed according to positions or the space where the ECU  10  is mounted. In this manner, the shape and the size of the side stays  33  are standardized not depending on vehicles on which the ECU  10  is mounted, and the ECU  10  can be easily carried by a conveyer system. It is also possible to directly mount the ECU  10  on the vehicle without using the separate brackets if such is suitable. 
     The side stay  33  includes a bent portion  35  bent upward with a substantially right angle. The height H (shown in FIG. 3) of the bent portion  35  is determined according to a width of a conveyer passage and the height of the ECU  10 , details of which will be explained later referring to FIGS. 3 and 4. A first rib  36  extending from the bottom plate  31  to the side stay  33  is formed on each side stay  33 , as shown in FIG.  2 . Also, a pair of second ribs  37  are formed along both sides of the bottom plate  31 . Both the first and the second ribs  36 ,  37  are formed in a convex shape having a cross-section such as a half-circular or triangular cross-section. The first rib  36  is perpendicularly connected to the second rib  37  at its center. 
     A depression  25  is formed at the bottom end of the sidewall  21   b ,  21   c , so that it engages with the first rib  36  when the case  11  and the bottom cover  14  are connected. The shape of the depression  25  is so formed that it corresponds to the convex shape of the first rib  36 . Since a pair of the first ribs  36  engage with a pair of depressions  25 , the bottom cover  14  is correctly positioned to the case  11  without fail. The first ribs  36  serve to increase mechanical strength of the side stays  33 . 
     As shown in FIG. 4, a number of ECUs  10  are carried by a conveyer system having a conveyer passage  40 . The conveyer passage  40  is defined by conveyer sidewalls  42 , and a conveyer belt  41  runs through the conveyer passage  40 . The ECUs  10  are placed on a conveyer belt  41  so that the rear side of each ECU  10  contacts the conveyer belt  41 . In other words, the ECUs  10  take standing positions on the conveyer belt  41 . The ECUs  10  contact one another at positions where the bent portions  35  are made. 
     FIG. 3 shows a top view of the conveyer passage  40 . The ECU  10  having its height W is placed in the conveyer passage  40  having its width L. A space δ1 at one side and another space δ2 at the other side are formed between the ECU  10  and the conveyer sidewalls  42 . The height H of the bent portion  35  is made to satisfy the relation: H&gt;(L−W). In other words, the height H is made larger than (δ1+δ2). Since the height H of the bent portion  35  is made to satisfy the above dimension, the bent portions  35  do not overlap one another when the ECUs  10  are conveyed in close contact to one another. 
     The case  11  and the bottom cover  14  are connected to each other as shown in FIG.  6 . The second ribs  37  are positioned inside the case  11 . Dusts or foreign particles entering into the inside space of the ECU  10  along the flat surface of side stays  33  are blocked by the second ribs  37 . If the dusts or foreign particles are electrically conductive, they are very harmful to stable operation of the ECU  10 . Those dusts or foreign particles are prevented from entering into the ECU  10  by the second ribs  37 . 
     As described above, since the side stay  33  includes the bent portion  35  having height H which is larger than the difference between width L of the conveyer passage  40  and height W of the ECU  10 , the ECUs  10  are smoothly carried by the conveyer system without causing jam or halt. Accordingly, production efficiency is enhanced. Further, the bent portions  35  serve to increase mechanical strength of the side stays  33 . The first ribs  36  formed on the side stays  33  further increase the mechanical strength of the side stays  33 . Accordingly, the side stays  33  have sufficient strength to endure a high vibrating force of a vehicle. The second ribs  37  formed along both sides of the bottom plate  31  not only increase the mechanical strength of the bottom cover  14  but also serve to prevent dusts or foreign particles from entering into the ECU  10 . The first and the second ribs  36 ,  37  are easily formed by presswork in the process of forming the bottom cover  14 . 
     The present invention is not limited to the embodiment described above, but it may be variously modified. For example, the maximum height H of the bent portion  35  may be limited though only the minimum dimension is specified in the foregoing embodiment. As shown in FIG. 5, a number of the bottom covers  14  are stacked in an assembly line of the ECU  10 , and they are picked up one by one. It may be difficult to stack the bottom covers  14  if the height H of the bent portion  35  is too large. To overcome this problem, the height H may be limited not to exceed a height Ha of the fringe wall  32 . Accordingly, a preferable dimension of the height H may be specified as: (L−W)&lt;H≦Ha. 
     The ECUs  10  may be carried by the conveyer, placing them on the conveyer belt with a flat posture instead of an upright posture. In this case, too, the bent portions  35  prevent the side stays  33  from overlapping one another on the conveyer belt. Accordingly, an automated arm can correctly pick up the ECU  10 . 
     Though the first ribs  36  are formed on the side stays  33  at the center thereof, the first ribs  36  may be formed at two or more places on each side stay  33 . The shape of the first rib  36  is not limited to the convex shape, but it may be formed in a concave shape. When the first rib  36  is formed in a concave shape, the depression  25  formed on the sidewall  21   b ,  21   c  has to be changed to a projection that fits the concave shape of the first rib. Though both the first rib  36  and the second rib  37  are formed in the embodiment described above, only the first rib  36  may be made, eliminating the second rib  37 . 
     While the present invention has been shown and described with reference to the foregoing preferred embodiment, it will be apparent to those skilled in the art that changes in form and detail may be made therein without departing from the scope of the invention as defined in the appended claims.