Abstract:
An actuator includes a lower housing member, an upper housing member ached to the lower one, and a cover member. Inside the lower housing member are arranged a driving source, a power-transmitting mechanism configured for transmitting a driving powder of the driving source to a output shaft to which a member to be driven is to be attached, a connector having terminals projected therefrom. A partition plate is provided in the upper housing member and has an opening for exposing said terminals of the connector and adapted to define a partition chamber opened to outside. A circuit board is placed on the partition plate, and has connection terminals connected to the terminals of the connector with a solder on the partition plate. A control circuit is assembled into the circuit board for the driving source. The cover member covers the circuit board.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     (1) Field of the Invention  
         [0002]     The present invention relates to an actuating device, particularly to an actuator suitably used for an air conditioner in a vehicle.  
         [0003]     (2) Related Art Statement  
         [0004]     Heretofore, the air conditioner for controlling the temperature of a vehicle compartment, for example, is assembled with an air-mixing door for adjusting a mixed amount of cooled air and warmed air as well as an actuator for driving the air-mixing door.  
         [0005]     The actuator comprises an upper housing member and a lower housing member. In the lower housing member, there are arranged a driving source, a circuit board for controlling operation of the driving source, a power-transmission mechanism for transmitting driving power of the driving source to an output shaft to which an air-mixing door is attached, a connector to which electric wires from the driving source are connected, a power input connector to which electric wires from a vehicle body are connected, etc.  
         [0006]     When the actuator is to be assembled, the driving source, the power-transmitting mechanism and the connectors are arranged inside the lower housing member, and the circuit board is assembled into the lower housing member by soldering the terminals of the connectors to respective connection terminals of the circuit board. Then, the upper housing member is attached to the lower housing member.  
         [0007]     When the terminals of the connectors are to be soldered to the respective connection terminals of the circuit board, an insulating flux is used as an auxiliary agent for facilitating the soldering work and assuredly fixing the solder to the circuit board. See JP-A 5-95177 (Page 2, FIG. 1), for example.  
         [0008]     However, when the terminals of the connectors are soldered to the respective connection terminals of the circuit board in the state that the circuit board is arranged inside the lower housing member, it is likely that solder balls and insulating flux scattering during soldering come in the lower housing member, because the circuit board is arranged inside the lower housing member without being isolated therein.  
         [0009]     When the actuator is assembled in the state that the solder balls are present inside the lower housing member, the balls may be caught by driving portions of the power-transmitting mechanism, etc., resulting in operational disorder.  
         [0010]     Further, if the scattered insulating flux attaches to a conductive portion of such as the connector, the flux-attached conductive portion becomes insulated, which may cause insufficient electric contact.  
         [0011]     In order to prevent invasion of the solder balls into the lower housing member and attachment of the flux to the conductive portion, it is a conventional practice that a invasion-preventing cover is placed over the driving source, the power-transmitting mechanisms, etc. arranged in the lower housing member during soldering or the circuit board is cleaned after soldering so as to remove excess solder remaining on the circuit board. According to these techniques, the number of steps increases and thus the production cost rises, although it is possible to prevent the operational disorder due to the solder balls being caught by the driving portion of the power-transmission mechanism, etc. and the insufficient electrical contact due to the attachment of the flux.  
       SUMMARY OF THE INVENTION  
       [0012]     It is therefore an object of the present invention to provide an actuator which makes it possible to suppress increase in the number of production steps and prevent invasion of solder balls and flux scattered during soldering into the lower housing member.  
         [0013]     In order to solve the above problem, the actuator according to the present invention comprises An actuator comprising a lower housing member, an upper housing member attached to said lower housing member, a cover member, a driving source, a power-transmission mechanism configured for transmitting a driving powder of said driving source to a output shaft to which a member to be driven is to be attached, a connector having terminals projected therefrom, said driving source and said power-transmission mechanism and said connector being arranged in the lower housing member, a partition plate provided in said upper housing member, having an opening for exposing said terminals of the connector and adapted to define a partition chamber opened to outside, and a circuit board having connection terminals connected to said terminals of the connector with a solder on said partition plate and having a control circuit assembled thereinto for said driving source, said cover member covering said circuit board.  
         [0014]     According to the actuator of the present invention, the partition chamber is defined in the upper housing member in such a manner that the partition chamber is opened outside the upper housing member, and the circuit board is arranged on the partition plate defining the partition chamber.  
         [0015]     Since the partition plate can be served to function as a conventional invasion-preventing cover, scattering solder balls and flux can be prevented from entering the lower housing member, while the driving source, the power-transmitting mechanism, etc. inside the lower housing member need not be covered with the conventional invasion-preventing cover during soldering or the circuit board needs not be cleaned after soldering. Further, since the number of producing steps is reduced, increase in the production cost can be suppressed.  
         [0016]     In a preferred embodiment of the present invention, said partition chamber is defined by said partition plate and a partition wall rising from said partition plate, and the partition chamber is closed with the cover member.  
         [0017]     By this construction, the partition chamber is opened outside the upper housing member, and defined by the partition plate and the partition wall rising from the partition plate. This construction makes it possible that the partition plate and the partition wall function in cooperation with each other as the conventional invasion-preventing cover, and that the scattering solder balls and flux can be more assuredly prevented from entering the lower housing during soldering.  
         [0018]     Since the partition chamber is closed with the cover member in the state that the cover member is attached to the partition chamber, the cover member functions similarly with the conventional housing in which the driving source, the power-transmitting mechanism, etc. are housed by the lower housing member and the upper housing member in cooperation with each other. Furthermore, when the cover member is attached to the partition chamber dust, etc. can be prevented from attaching to the circuit board arranged on the partition plate.  
         [0019]     According to the present invention, the partition chamber is defined in the upper housing member by the partition plate and the partition wall, and the circuit board is arranged on the partition plate. According to this construction, since the partition plate and the partition wall can be served as the invasion-preventing cover, solder balls and flux scattered during soldering can be prevented from entering the lower housing member, while the driving source, the power-transmitting mechanism, etc. arranged inside the lower housing member need not be covered with the conventional invasion-preventing cover during soldering or the circuit board needs not be cleaned after soldering. Further, since the number of producing steps can be reduced, increase in the production cost can be suppressed.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     For a better understanding of the invention, reference is made to the attached drawings, wherein:  
         [0021]      FIG. 1  is an exploded perspective view of schematically illustrating an actuator according to one embodiment of the present invention.  
         [0022]      FIG. 2  is a plane view of schematically illustrating a lower housing member of the above embodiment of the present invention in which a driving source, a power-transmitting mechanism, etc. are arranged. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     The present invention will be explained in more detail with reference to one embodiment of an actuator  10  of the present invention shown in  FIGS. 1 and 2 , which is merely illustrative of the invention but not intended to limit the scope of the claimed invention.  
         [0024]     The actuator to which is embodied the present invention is assembled into an air conditioner for controlling the temperature of a vehicle compartment.  
         [0025]     Although not illustrated but conventionally well known, the actuator  10  according to the present invention is used as an actuating apparatus for operating an air-mixing door  11  as a member to be driven in an air passage of the air conditioner so as to adjust a mixed ratio between exterior air cooled with a heat exchanger provided in the air conditioner and air warmed through a heater core using engine-cooling water as a heat source.  
         [0026]      FIG. 1  is an exploded perspective view of schematically illustrating the actuator  10 . As shown in  FIG. 1 , the actuator  10  comprises a lower housing member  20 , an upper housing member  30  to be attached to the lower housing member  20 , a circuit board  40  and a cover member  50 .  
         [0027]     The lower housing member  20  comprises a bottom wall  12  and a peripheral wall  13  rising perpendicularly from a peripheral edge  12   a  of the bottom wall. As shown in  FIGS. 1 and 2 , the peripheral wall  13  is formed with a rectangular cutaway portion  14  extending from an upper edge  13   a  of the peripheral wall toward a bottom wall  12 .  
         [0028]     As also shown in  FIG. 2 , inside the lower housing member  20  are arranged a motor  15  as a driving source of the actuator  10 , a power-transmitting mechanism  17  constituted by a row of gears  16   a ,  16   b ,  16   c  and  16   d  for transmitting the rotation of the motor  15  via a worm gear  24  fixed to a rotary shaft  15   b  thereof and reducing the rotation, an output shaft  18  which is a rotary shaft for the final-stage gear  16   d  of the power-transmitting mechanism and to which an air-mixing door  11  is fixed, a potentiobalance resistor  19  (hereinafter referred to as PBR), a motor connector  21  to which electric wires  15   a  from the motor  16  are connected and a power input connector  23  to which electric wires  22  (See  FIG. 1 ) from a vehicle body are connected.  
         [0029]     As mentioned latter in detail, the motor connector  21 , the power input connector  23  and the PBR  19  are connected to a circuit board  40  arranged in an upper housing member  30 .  
         [0030]     The motor connector  21  is provided with a pair of projecting terminals  21   a  to which electric wires  15   a  of the motor  15  are connected. The connector  21  is arranged inside the lower housing member  20  together with the terminals  21   a  in the state that the connector  21  is supported by a support  26  provided inside the lower housing member  20 , while the connector  21  projects upwardly out of the lower housing member  20  together with the terminals  21   a.    
         [0031]     The power input connector  23  has three projecting terminals  23   a  in the illustrated embodiment, and is received in a housing portion  25  inside the lower housing member  20 , while the connector  23  projects upwardly out of the lower housing member  20  together with the terminals  23   a . The electric wires  22  from the vehicle body are connected to the power input connector  23  through an opening (not shown) formed in the bottom wall  12  of the lower housing member  20 .  
         [0032]     A rotation position or a rotation angle of the mixing door  11  is detected by the PBR  19 . The PBR  19  is arranged between the final-stage gear  16   d  and the bottom wall  12  of the lower housing member  20 , and has three terminals  19   a ,  19   b  and  19   c  projecting upwardly out of the lower housing member  20 . As well known heretofore, voltage corresponding to the rotation angle of the air-mixing door  11  is outputted as an electric signal to the central terminal  19   b , while voltage is applied to the opposite side terminals  19   a  and  19   c.    
         [0033]     The circuit board  40  to be arranged in the upper housing member  30  has connection terminals  40   a  to which the terminals  21   a  of the motor connector  21 , the terminals  23   a  of the power input connector  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19  are connected, respectively.  
         [0034]     As well known heretofore, when a temperature control level (not shown) provided in the vehicle compartment is operated, an electric signal representing a target value of the rotation angle of the air-mixing door  11  that corresponds to the location of the operated temperature control lever is inputted to the power input connector  23  via the electric wire  22  from the vehicle compartment.  
         [0035]     The circuit board  40  receives the electric signals representing the target value from the terminals  23   a  of the power input connector  23  and the electric signal from the terminal  19   b  of the PBR  19 , determines a difference between the target value and the rotation angle of the air-mixing door  11  detected by the PBR  19  based on these electric signals, and feedback controls the operation of the motor  15  via the motor connector  21  by means of a control circuit (not shown) so that the detected value may be in coincidence with the target one.  
         [0036]     As mentioned above, the air-mixing door  11  attached to the output shaft  18  is controlled to an angle corresponding to the target value of the temperature control lever by the feedback control based on the control signal.  
         [0037]     As shown in  FIG. 1 , the upper housing member  30  on which is arranged the circuit board includes a top wall  29 , and a peripheral wall  31  downwardly extending from a peripheral edge  29   a  of the top wall.  
         [0038]     When the upper housing member  30  is attached to the lower housing member  20 , a lower edge  31   a  of the peripheral wall  31  can be butted to an upper edge  13   a  of the peripheral wall  13  of the lower housing member  20 . Further, the peripheral wall  31  is designed at such a height that the motor  15 , the power-transmitting member, etc. placed in the lower housing member  20  may be sufficiently housed inside the assembly of the lower housing member  20  and the upper housing member  30  in combination in the state that both the housing members are attached together.  
         [0039]     The peripheral wall  31  is constituted by a pair of long-side wall portions  32   a  and  32   b  and a pair of short-side wall portions  33   a  and  33   b . At an end portion  33   d  of a lower edge  33   c  of the short-side wall portion  33   a  is formed with a rectangularly projecting plate portion  43  extending in a direction away from the top wall  29 .  
         [0040]     At one of four corners on a side of the top wall  29  is formed an opened area  34  opened outside the upper housing member  30 . That portion of the top wall  29  which defines the corner formed with the opened area  34  is cut away in a rectangular shape. Similarly, a part of each of the long-side wall portion  32   a  and the short-side wall portion  33   a  which define that corner is cut away in a rectangular shape, leaving their respective lower edges  32   c  and  33   c.    
         [0041]     Inside the opened area  34  is formed a rectangular partition plate  35  which continues to the uncut lower edge  33   c  of the short-side wall portion  33   a  and the uncut lower edge  32   c  of the long-side wall portion  32   a  and extends as a bottom wall of the opened area in parallel to the top wall  29  inside the opened area  34 .  
         [0042]     The partition plate  35  is formed with openings  39   a ,  39   c  and  39   b  corresponding to the motor connector  21 , the power input connector  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19 , respectively. The openings have such dimensions as to allow the connectors  21  and  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19  to be inserted therethrough, respectively.  
         [0043]     Partition walls  36  and  37  continuing to the edges  35   a  and  35   b  and rising perpendicularly toward the top wall  29  from the ends  35   a  and  35   b  are formed at end edges  35   b  of the partition plate  35  opposed to the lower edge  33  of the short-side wall portion  33   a  and the edge  35   a  of the partition plate  35  opposed to the lower edge  32   c , respectively. In central portions of the upper edge portion  36   a  and the upper edge portion  37   a  of the partition wall  37  are formed engaging portions  42  to be engaged with engaging pawls  41  of the cover member  50  as mentioned later.  
         [0044]     A partition chamber  38  is defined by the partition plate  35  and the partition walls  36  and  37  such that the chamber is separated from the other portion of the upper housing member  30  and opened outside the upper housing member.  
         [0045]     The cover member  50  has such a dimension that the partition chamber  38  formed in the upper housing member  30  may be closed with the cover member. The cover member  50  has a top wall  44  and a peripheral wall  45  extending downward from a peripheral edge  44   a  of the top wall  44 . The top wall  44  is formed with the engaging pawls  41  in locations corresponding to the engaging portions  42  formed at the upper housing member  30 , while projecting from the peripheral edge  44   a  of the top wall  44 .  
         [0046]     When the actuator  10  is assembled, the motor  15 , the power-transmitting mechanism  17 , the PBR  19 , the motor connector  21  and the input connector  23  are arranged in the lower housing member  20 , and then the upper housing member  30  is attached to the lower housing member  20 . By this attachment, the lower edge  31  of the upper housing member  30  is butted to the upper edge  13   a  of the lower housing member  20 . Further, the projecting plate portion  43  formed at the upper housing member  30  is attached into the cutaway portion  14  formed in the lower housing member  20 . By this construction, the upper housing member  30  is attached to the lower housing member  20  precisely at a predetermined attachment position.  
         [0047]     By this engagement, the motor connector  21 , the power input connector  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19  arranged in the lower housing member  20  are inserted through the openings  39   a ,  39   c  and  39   b  formed in the partition plate  35 , respectively. By this, the terminals  21   a  of the connector  21 , the terminals  23   a  of the connector  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19  are exposed inside the partition chamber  38  through the openings  39   a ,  39   b  and  39   c , respectively.  
         [0048]     The circuit board  40  is placed on the partition plate  35  to cover the terminals  21   a  of the connector  21 , those  23   a  of the connector  23  and those  19   a ,  19   b  and  19   c  of the PBR  19 , which are exposed inside the partition chamber  38  through the openings  39   a ,  39   b  and  39   c  of the partition plate  35 , respectively. As mentioned above, the terminals  21   a ,  23   a  and  19   a ,  19   b  and  19   c  are connected to the corresponding connection terminals  40   a  of the circuit board  40  on the partition plate  35  by soldering. In soldering, as well known, an insulating flux, for example, may be used as an auxiliary agent for facilitating the soldering and assuredly fixing the solder onto the circuit board  40 .  
         [0049]     Since the terminals  21   a ,  23   a  and  19   a ,  19   b  and  19   c  are connected to the connection terminals  40   a  of the circuit board  40  inside the partition chamber  38 , the partition plate  35  and the partition walls  36  and  37  defining the partition chamber  38  function as an invasion-preventing cover conventionally used. Therefore, solder balls and flux scattering during soldering will not enter the lower housing member  20 .  
         [0050]     Thereafter, the cover member  50  is attached to the partition chamber  38  so as to cover the circuit board  40  to which the terminals  21   a ,  23   a  and  19   a ,  19   b  and  19   c  are soldered. By this attachment, the engaging pawls  41  formed at the cover member  50  are engaged with the engaging portions  42  formed in the partition walls  36  and  37 , respectively. By this engagement, the cover member  50  is attached to the partition chamber  38  at such a closing location as to assuredly close the partition chamber  38 .  
         [0051]     The top wall  44  and the peripheral wall  45  of the cover member  50  are in flush with the top wall  29  and the peripheral wall  31  of the upper housing member  30  in the state that the cover member  50  is attached to the partition chamber  38 .  
         [0052]     In this embodiment, as mentioned above, the partition chamber  38  is defined in the upper housing member  30  by the partition plate  35  and the partition walls  36  and  37 , and the circuit board  40  is arranged on the partition plate  35 . By so constructing, the partition plate  35  and the partition walls  36  and  37  function as an invasion-preventing cover conventionally used. Therefore, solder balls and flux scattering during soldering can be assuredly prevented from entering the lower housing member  20 , without placing such a conventional invasion-preventing cover over the motor  15 , the power-transmitting mechanism  17 , etc. arranged in the lower housing member  20  during soldering or cleaning the circuit board  40  after the soldering.  
         [0053]     Further, the number of the producing steps can be reduced, and increase in the production cost can be suppressed through the formation of the partition chamber  38  by eliminating the conventional need to use the invasion-preventing cover during soldering or cleaning the circuit board  40  after the soldering.  
         [0054]     Furthermore, since the partition chamber  38  is closed by attaching the cover member  50  to the partition chamber  38 , the cover member  50  can function as the housing in corporation with the lower housing member  20  and the upper housing member  30  as in the conventional housing in which the motor  15 , the power-transmitting mechanism  17 , etc. are housed. Furthermore, dust can be assuredly prevented from being deposited upon the circuit board  40  arranged on the partition plate  35  by closing the partition chamber  38  with the attachment of the cover member  50  thereto.  
         [0055]     In this embodiment, the partition plate  35  is formed with the openings  39   a ,  39   b  and  39   c  in locations corresponding to the motor connector  21 , the power input connector  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19 , respectively, the motor connector  21 , the power input connector  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR are inserted through these respective openings when the upper housing member  30  is attached to the lower housing member  20 . In place of the formation of the above openings, insertion holes are formed in the partition plate  35  at locations corresponding to the terminals  21   a ,  23   a ,  19   a ,  19   b  and  19   c  of the connectors  21  and  23  and the PBR  19 , respectively, in such a dimension as to allow insertion of only the terminals therethrough.  
         [0056]     Moreover, in this embodiment, although the partition chamber  38  is formed in the corner of the upper housing member  30 , the place where the partition chamber  38  is formed can be arbitrarily varied depending upon the arranging places of the connectors  21  and  23  and the terminals  19   a ,  19   b  and  19   c  of the PBR  19  inside the lower housing member  20 . In addition, when each of the lower housing member  20  and the upper housing member  30  has a spherical shape as viewed sectionally in plane, each of the partition walls and the partition plate constituting the partition chamber  30  may be designed in a fan-like shape, for example.  
         [0057]     When the terminals  21   a ,  23   a  and  19   a ,  19   b  and  19   c  of the connectors  21  and  23  and the PBR  19 , respectively are soldered to the connection terminals  40   a  of the circuit board  40 , the solder is not limited to only a common solder such as Sn-Pb based solder, but various solders such as a so-called Pb-free solder containing no Pb may be used.