Patent Publication Number: US-8113864-B2

Title: Quick-detachable terminal seat and programmable logic controller having the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a terminal seat, and in particular to a quick-detachable terminal seat and a programmable logic controller having the same. 
     2. Description of Prior Art 
     A terminal seat is a common part in an electronic apparatus. For example, a programmable logic controller (PLC) commonly used in industrial automation is provided with a terminal seat whose surface is arranged with several rows of terminals. A portion of terminals is electrically connected to a circuit board of the PLC, while the other portion of terminals is electrically connected to other electronic elements (such as sensors or controllers) via leads. Finally, the terminal seat is locked to a casing of the PLC. For example, in case of a switchboard on a large-sized electronic apparatus, a plurality of terminal seats is arranged side by side on the switchboard. Since the distance between these terminals is so close that the space available for arranging leads becomes narrow. Even, an operator for arranging the leads may touch the terminals carelessly and thus get an electric shock. 
     In view of the above, the industry in this art develops a detachable terminal seat, whereby the operator can connect a plurality of leads to the predetermined terminals in advance. Then, the whole detachable terminal seat is electrically connected to the circuit board and fixed to the switchboard. In this way, the problem of narrow space and the risk of getting an electric shock can be avoided. 
     However, in practice, such a detachable terminal seat still has drawbacks as follows. First, since most of the detachable terminal seats are fixed to the switchboard via screws, the operator needs to use an additional tool (such as a screw driver) to loosen the screws in order to detach the terminal seat from the switchboard. As a result, during the detachment of the terminal seat, the problem of narrow space and the risk of getting an electric shock still exist. Some detachable terminal seats are fixed to the switchboard via fasteners or plastic knobs. Although such an arrangement allows the operator not to use a tool, the operator still needs to hold the terminal seat by one hand, loosen the fastener or plastic knob by the other hand, and then pull the terminal seat out of the switchboard with labor. When a plurality of detachable terminal seats is arranged side by side with the top surfaces of two adjacent terminal seats being in flush with each other, it is difficult for the operator to find a point on the aligned surfaces for exerting a force to pull the terminal seat out of the switchboard. 
     In prior art, another kind of detachable terminal seat is developed, in which a pull rod is provided. This pull rod functions as an insertion pin for inserting into the terminal seat to thereby fix the rear end of the terminal seat to a casing. However, such a pull rod cannot lift up the terminal seat. Thus, when the operator intends to pull the terminal seat out of the switchboard, the operator has to pull the pull rod out of the terminal seat, and then pull the terminal seat out of the casing. Therefore, the problem of narrow space and difficulty in finding a point for exerting forces still exist. 
     In the conventional detachable terminal seat, not only its fixation to the casing is defective, but also the operator needs to exert a larger force to detach the terminal seat from the circuit board. On the other hand, the operator has to align the terminal seat with the circuit board, and then press the terminal seat into the casing to complete the assembly. Thus, if a labor-saving mechanism could be provided in the conventional detachable terminal seat, the detachment of the terminal seat may become easier. 
     Therefore, it is an important issue for the present inventor to solve the above problems. 
     SUMMARY OF THE INVENTION 
     The present invention is to provide a quick-detachable terminal seat, which can be easily fixed to a casing of a controller without using an additional tool. Further, such a terminal seat can be detached quickly in a labor-saving manner. 
     The present invention is to provide a programmable logic controller having a quick-detachable terminal seat, in which the terminal seat can be easily fixed to a casing of the programmable logic controller without using an additional tool. Further, the terminal seat can be quickly detached from the casing of the controller in a labor-saving manner. 
     The present invention provides a quick-detachable terminal seat, configured to be mounted on a casing of a programmable logic controller, the periphery of the casing being provided with a notch and a locking slot, the terminal seat comprising: a main body having at least one guiding rib on its one side surface; and a pull rod slidingly inserted into the main body, one side surface of the pull rod being formed with a groove for allowing the at least one guiding rib to be inserted therein, a rear end of the pull rod having a first hook engaged with the locking slot, the pull rod having a first inclined surface formed on one side surface opposite to the groove and located corresponding to the notch; wherein the first inclined surface moves upwards with respect to the notch when the pull rod is pulled out of the main body with the first hook being disengaged from the locking slot, the terminal seat can be moved upwards with respect to the casing and detached there from. 
     The present invention provides a programmable logic controller, which comprises: a casing having a notch and a locking slot on its periphery; and a quick-detachable terminal seat, configured to be mounted on the casing and comprising: a main body having at least one guiding rib on its one side surface; and a pull rod slidingly inserted into the main body, one side surface of the pull rod being formed with a groove for allowing the at least one guiding rib to be inserted therein, a rear end of the pull rod having a first hook engaged with the locking slot, the pull rod having a first inclined surface formed on one side surface opposite to the groove and located corresponding to the notch; wherein the first inclined surface moves upwards with respect to the notch when the pull rod is pulled out of the main body with the first hook being disengaged from the locking slot, the terminal seat can be moved upwards with respect to the casing and detached there from. 
     In comparison with prior art, the present invention has advantageous features as follows: 
     According to the present invention, since the pull rod is slidingly inserted into the main body and the first hook of the pull rod is engaged with the locking slot of the casing of the programmable logic controller, the terminal seat can be engaged with the casing quickly. Thus, no locking elements such as screws, fasteners or plastic knobs are needed for fixing the terminal seat to the casing of the programmable logic controller. 
     According to the present invention, since the user only needs to press the pull rod inwards to generate the engagement between the terminal seat and the casing of the programmable logic controller, or pull outwards the pull rod to release the engagement between the terminal seat and the casing, the operation of the present invention becomes easier. Furthermore, the problem that the user may not find a point in a narrow space or on surfaces of aligned terminals for exerting forces to remove the terminal seat can be avoided. 
     According to the present invention, since the pull rod is made of plastic materials, the operator may not touch the metallic parts in the terminal seat such as terminals or screws when pulling the pull rod, the risk of getting an electric shock can be avoided. 
     According to the present invention, since the pull rod is provided with a first inclined surface, and the first inclined surface can be moved upwards by means of the reaction with the notch of the casing, the operator can remove the terminal seat from the casing quickly in a labor-saving manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view showing a quick-detachable terminal seat of the present invention; 
         FIG. 2  is an assembled perspective view showing the quick-detachable terminal seat of the present invention; 
         FIG. 3  is an assembled side view showing a quick-detachable terminal seat of the present invention; 
         FIG. 4  is an exploded perspective view showing a programmable logic controller of the present invention; 
         FIG. 5  is a partially side cross-sectional view of the programmable logic controller of the present invention, showing that a pull rod is not inserted into a casing of the controller completely; 
         FIG. 6  is a partially side cross-sectional view of the programmable logic controller of the present invention, showing that the pull rod is inserted into the casing of the controller completely; 
         FIG. 7  is a partially side cross-sectional view of the programmable logic controller of the present invention, showing that the pull rod is to be removed from the casing of the controller; and 
         FIG. 8  is a partially side cross-sectional view of the programmable logic controller of the present invention, showing that the pull rod has been removed from the casing of the controller to lift up the terminal seat. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The detailed description and technical contents of the present invention will be explained with reference to the accompanying drawings. However, it should be understood that the drawings are illustrative only, but not used to limit the present invention. 
     Please refer to  FIGS. 1 to 4 . The present invention provides a quick-detachable terminal seat  1  and a programmable logic controller  100  having the terminal seat  1 . The terminal seat  1  includes a main body  10  and a pull rod  20 . The programmable logic controller  100  includes the terminal seat  1  and a casing  30  shown in  FIG. 4 . 
     It should be noted that the directional term “front” refers to a direction along which the pull rod  20  is inserted into the main body  10 , while the directional term “rear” refers to the reverse direction of the “front”. As a result, the directional terms “top” and “bottom” can be defined accordingly. 
     As shown in  FIG. 1 , the main body  10  is substantially formed into a rectangular body and has at least one row of connecting terminals  11  on its top surface. In the present embodiment, two rows of connecting terminals  11  are provided. Since the structure of the connecting terminals  11  is well known, the description relating thereto is omitted. The bottom surface of the main body  10  is provided with a slot  12  in which a circuit board  31  of the casing  30  shown in  FIG. 4  can be inserted to achieve an electrical connection there between. The interior of the slot  12  is provided with a plurality of electrical-conductive terminals  121 . Each of the electrical-conductive terminals  121  is electrically connected to a connecting terminal  11 , thereby achieving the electrical connection between the main body  10  and the casing  30 . 
     One side surface of the main body  10  is formed with at least one guiding rib  13 . In the present embodiment, two guiding ribs  13  and  14  are provided at an interval in a line. Two fixing ribs  15  and  16  are provided in parallel to the guiding ribs  13  and  14  respectively. One end of each of the fixing ribs  15  and  16  is formed with a chamfer for smoothing the insertion of the pull rod  20  into the main body  10 . It should be noted that, as shown in  FIG. 1 , the two guiding ribs  13 ,  14  and the two fixing ribs  15 ,  16  are positioned in a staggered arrangement. 
     The pull rod  20  is a rod made of plastic materials. The pull rod  20  includes a groove  21  formed on one side surface of the pull rod  20  for allowing the guiding ribs  13 ,  14  to be inserted therein, a first hook  22  formed on the rear end of the pull rod  20 , and a second hook  23  formed on the front end of the pull rod  20 . When the pull rod  20  is inserted into the main body  10 , the pull rod  20  is restricted between the two fixing ribs  15 ,  16  and the guiding ribs  13 ,  14 , so that the pull rod  20  can only slide forwards or rearwards in the extending direction of the groove  21 . Further, the rear end of the pull rod  20  is formed with an operating portion  24 . The operating portion  24  is formed on the top of the rear end of the pull rod  20 , while the first hook  22  is formed on the bottom of the rear end of the pull rod  20 . Taking the ergonomics into consideration, the operating portion  24  is made concave to form an operating space S (as shown in  FIG. 3 ) between the operating portion  24  and the main body  10 . The front end of the operating portion  24  is formed with a positioning end  241  for abutting the main body  10 . With this arrangement, the operator can put his finger into the operating space S to pull the pull rod  20  out of the main body  10 . Thus, the problem in prior art that the operator may not find a point for exerting force can be solved. 
     The first hook  22  is provided on the bottom of the rear end of the pull rod  20  for fixing the rear end of the main body  10  to the casing  30 . 
     The front side of the second hook  23  is formed with a guiding surface  231 . Since the pull rod  20  is made of plastic materials, when the pull rod  20  is inserted into the main body  10 , the guiding surface  231  is brought into contact with the chamfers of the fixing ribs  15 ,  16  successively, so that the second hook  23  suffers an elastic deformation to cross the fixing ribs  15  and  16 . In this way, the guiding ribs  13  and  14  can be smoothly inserted into the groove  21  of the pull rod  20 , and the pull rod  20  can slide forwards in the direction of the groove  21  with respect to the main body  10 . When the second hook  23  moves beyond the fixing rib  16 , the second hook  23  is blocked by the fixing rib  16 , thereby preventing the accidental disengagement of the pull rod  20  from the main body  10 . 
     The second hook  23  has a recessed portion  232  for fixing the front end of the main body  10  to the casing  30 . The rear end and the front end of the main body  10  can be fixed to the casing  30  by means of the first hook  22  and the second hook  23  respectively. Thus, no locking elements such as screws, fasteners or plastic knobs are provided for fixing the terminal seat  1  to the casing  30 . 
     The pull rod  20  is formed with a first inclined surface  25  on one side surface opposite to the groove  21 . The rear side of the second hook  22  is formed with a second inclined surface  233 . The slope of the first inclined surface  25  is substantially the same as that of the second inclined surface  233 . With this arrangement, the first inclined surface  25  is configured to lift up the rear end of the main body  10 , and the second inclined surface  233  is configured to lift up the front end of the main body  10 . In this way, the operator can remove the main body  10  from the casing  30  in a labor-saving manner, which will be described in more detail later. 
     As shown in  FIG. 4 , the casing  30  of the programmable logic controller  100  has a trough  32  for allowing the main body  10  to be inserted therein, thereby generating an electrical connection between the main body  10  and the circuit board  31  of the casing  30 . One side of the trough  32  is provided with two notches  33  and  34 . The two notches  33  and  34  are positioned to correspond to the first inclined surface  25  and the second inclined surface  233  respectively. The casing  30  is provided with two locking slots  35  and  36 . The first hook  22  is engaged with the locking slot  35 , and the second hook  23  is engaged with the locking slot  36 . Since the pull rod  20  is assembled with the main body  10 , the engagement between the hooks  22 ,  23  of the pull rod  20  and the casing  30  can cause the main body  10  to be assembled with the casing  30 . 
     Next, the operation of the present invention will be described. 
     First, the pull rod  20  has to be inserted into the main body  10  according to the steps as follows. The groove  21  of the pull rod  20  is aligned with the guiding rib  13  of the main body  10 , and then the pull rod  20  is pressed forwards into the main body  10 . At this time, the guiding surface  231  of the second hook  23  of the pull rod  20  is brought into contact with the chamfer of the fixing rib  15  of the main body  10 , while the guiding rib  13  is inserted into the groove  21  of the pull rod  20 . The guiding surface  231  suffers a downward elastic deformation to cross the fixing rib  15  of the main body  10 . Thereafter, the operator presses the pull rod  20  further forwards. At this time, the guiding surface  231  of the pull rod  20  is brought into contact with the chamfer of the fixing rib  16  of the main body  10 . In this position, the pull rod  20  is restricted by the two fixing ribs  15  and  16  from any further transverse movement, so that the pull rod  21  can be only moved forwards or rearwards in the extending direction of the groove  21 . Then, the second hook  23  of the pull rod  20  is allowed to cross the fixing rib  16 . When the second hook  23  crosses the fixing rib  16  without reaching the front edge of the main body  10 , the second hook  23  is located in a movable region. The operator has to press the pull rod  20  into the main body  10  until the second hook  23  is located in the movable region. If the pull rod  20  is pushed further forwards with the positioning end  241  of the operating portion  24  abutting the edge of the main body  10 , as shown in  FIG. 3 , the pull rod  20  cannot slide any further. 
     Next, please refer to  FIGS. 5 to 8 . The description relating to how the combination of the main body  10  and the pull rod  20  is inserted into the casing  30  and fixed thereto will be made. 
     As shown in  FIG. 5 , when the pull rod  20  is inserted into the main body  10  with the second hook  22  being located in the movable region, the operator presses the main body  10  downwards to be inserted into the trough  32  of the casing  30  as shown in the arrow. At this time, the first inclined surface  25  and the second inclined surface  233  of the pull rod  20  are accommodated in the two notches  33  and  34  of the casing  30  respectively. 
     As shown in  FIG. 6 , the operator then presses the operating portion  24  of the pull rod  20  inwards. At this time, the guiding surface  231  of the second hook  23  of the pull rod  20  suffers a downward elastic deformation, so that the recessed portion  232  of the second hook  23  is engaged with the locking slot  36  at the front end of the casing  30 , while the first hook  22  is engaged with the locking slot  35  at the rear end of the casing  30 , thereby fixing the front end and rear end of the main body  10 . I this way, the main body  10  cannot be detached from the casing  30  easily. 
     As shown in  FIG. 7 , when the operator intends to detach the main body  10  from the casing  30 , the operator can put his finger into the operating space S of the operating portion  24  to pull the pull rod  20  rearwards. In this way, the first hook  22  and the second hook  23  are disengaged from the locking slots  35  and  36  respectively. At this time, the first inclined surface  25  and the second inclined surface  233  abut the notches  33  and  34  of the casing  30  respectively. 
     As shown in  FIG. 8 , when the operator pulls the operating portion  24  of the pull rod  20  further rearwards, the first inclined surface  25  and the second inclined surface  233  are moved upwards with respect to the notches  33  and  34  respectively, so that the main body  10  and the pull rod  20  can move upwards a small distance with respect to the casing  30 . In this way, the slot  12  of the main body  10  can be separated from the circuit board  31  of the casing  30 , thereby detaching the terminal seat  1  from the casing  30 . 
     In comparison with prior art, the present invention has advantageous features as follows: 
     According to the present invention, since the pull rod  20  is slidingly inserted into the main body  10  and the first hook  22  and the second hook  23  of the pull rod  20  are engaged with the locking slots  35  and  36  of the casing  30  respectively, the terminal seat  1  can be engaged with the casing  30  quickly. Thus, no locking elements such as screws, fasteners or plastic knobs are needed for fixing the terminal seat  1  to the casing  30  of the programmable logic controller  100 . 
     According to the present invention, since the user only needs to press the pull rod  20  inwards to generate the engagement between the terminal seat  1  and the casing  30 , or pull outwards the pull rod  20  to release the engagement between the terminal seat  1  and the casing  30 , the operation of the present invention becomes easier, and the user needs not to use an addition tool. Furthermore, the problem that the user may not find a point in a narrow space or on the surfaces of aligned terminals for exerting force to remove the terminal seat  1  can be avoided. 
     According to the present invention, since the pull rod  20  is made of plastic materials, the operator may not touch the metallic parts in the terminal seat  1  such as terminals or screws when pulling the pull rod  20 , the risk of getting an electric shock can be avoided. 
     According to the present invention, since the pull rod  20  is provided with a first inclined surface  25  and a second inclined surface  233 , the first inclined surface  25  and the second inclined surface  233  can be moved upwards by means of the reaction with the notches  33  and  34  of the casing  30 , so that the operator can remove the terminal seat  1  from the casing  30  quickly in a labor-saving manner. 
     Although the present invention has been described with reference to the foregoing preferred embodiments, it will be understood that the invention is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the invention as defined in the appended claims.