Patent Publication Number: US-8987950-B2

Title: Actuator and actuator cooling method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure contains subject matter related to that disclosed in Japanese Priority Patent Application No. 2011-231157 filed with the Japan Patent Office on Oct. 20, 2011, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     An embodiment disclosed herein relates to an actuator and an actuator cooling method. 
     2. Description of the Related Art 
     Conventionally, there is known an actuator provided with a drive device such as a linear motor for linearly moving a movable member. Moreover, an actuator incorporating a plurality of drive devices is under development and is used as, e.g., a component transfer device for moving a plurality of components to a specified place while holding them (see, e.g., Japanese Patent Application Publication No. 2001-105270). 
     SUMMARY OF THE INVENTION 
     An actuator in accordance with an aspect of an embodiment includes: one or more drive devices, each being configured to linearly move a movable member; a partition member provided close to the movable member and configured to partition a space defined between the movable member and a control device for controlling the drive devices; and a fan arranged on the side of the movable member with respect to the partition member and configured to flow an air existing in a partitioned space on the side of the movable member with respect to the partition member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic view showing an actuator in accordance with a first embodiment; 
         FIG. 1B  is a schematic view of the actuator equipped with a control board; 
         FIG. 2  is a section view taken along line II-II in  FIG. 1B ; 
         FIG. 3  is a section view taken along line III-III in  FIG. 2 ; 
         FIG. 4A  is a section view taken along line IVA-IVA in  FIG. 3 ; 
         FIG. 4B  is a section view taken along line IVB-IVB in  FIG. 4A ; 
         FIG. 5  is an explanatory view illustrating a case where the intervals between guide members are varied depending on the distance from a fan; and 
         FIG. 6  is an explanatory view illustrating a case where fins are provided in a partition member. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of an actuator and an actuator cooling method disclosed in the subject application will now be described with reference to the accompanying drawings. However, the actuator and the actuator cooling method are not limited to the embodiments to be described below. 
     (First Embodiment) 
       FIG. 1A  is a schematic view showing an actuator in accordance with a first embodiment.  FIG. 1B  is a schematic view of the actuator equipped with a control board. The actuator in the first embodiment is used as, e.g., a head module of a component transfer module for moving a component to a specified place while holding the component. 
     As shown in  FIG. 1A , the actuator  1  in the present embodiment includes a plurality of linear motors  10 , a frame  20 , a partition member  30  and a fan  40 . 
     Each of the linear motors  10  is a drive device for linearly moving a shaft  11  inserted into a tubular guide member  12  along the guide member  12 . The guide member  12  serves also as a magnetic motor frame. As the opposite end portions of the guide member  12  are supported by a first support portion  21  and a second support portion  22  of the frame  20 , each of the linear motors  10  is fixed to the frame  20 . The shaft  11  of each of the linear motors  10  is linearly movably supported by a third support portion  25  attached to the first support portion  21 . 
     The actuator  1  in the first embodiment is provided with ten linear motors  10 . Ten guide members  12  corresponding to the respective linear motors are arranged side by side. The number of the linear motors of the actuator is not limited to ten, and a single linear motor serving the drive device may be provided. 
     The frame  20  includes the first support portion  21 , the second support portion  22 , a sidewall portion  23 , a plurality of posts  24   a  to  24   d  and the third support portion  25 . 
     The first support portion  21  and the second support portion  22  are members for respectively supporting the tip end portions and the base end portions of the guide members  12 . The sidewall portion  23  is a member for covering the side surfaces of the guide members  12  and is arranged between the fan  40  and the guide member  12  positioned nearest to the fan  40 . In the sidewall portion  23 , there is formed a cutout portion for allowing the air blown by the fan  40  to be directly contacted with the guide members  12 . Detail description thereof will be made later. 
     The posts  24   a  so  24   d  are members for supporting the control board of the linear motors  10  to be described later. The posts  24   a  and  24   b  are arranged in, e.g., the first support portion  21 . The posts  24   c  and  24   d  are arranged in, e.g., the second support portion  22 . 
       FIG. 1B  is a schematic view of the actuator  1  equipped with the control board of the linear motors  10 . As shown in  FIG. 1B , a board plate  50  is mounted on the upper end portions of the posts  24   a  to  24   d . A control board  60  of the linear motors  10  is mounted on the board plate  50 . The control board  60  is a control device for controlling the linear motors  10 . 
     Referring back to  FIG. 1A , description will be made on the partition member  30 . The partition member  30  is a member for partitioning the space between the board plate  50  and the guide members  12 . The fan  40  is arranged on the side of the guide members  12  with respect to the partition member  30  and is configured to flow the air existing in a partitioned space on the side of the guide members  12 . 
     In the actuator  1  of the first embodiment, the space between the board plate  50  and the guide members  12  is partitioned by the partition member  30 . The air existing in the partitioned space on the side of the guide members  12  with respect to the partition member  30  is blown by the fan  40 , thereby suppressing a temperature increase around the linear motors  10  and the shaft  11 . Description will now be made on the arrangement and configuration of the partition member  30  and the fan  40 . 
     In the following description, as shown in  FIG. 1A , the moving direction of the shaft  11  will be referred to as X-axis direction, the arranging direction of the guide members  12  will be referred to as Y-axis direction and the direction orthogonal to the X-axis and the Y-axis will be referred to as Z-axis direction. Moreover, the positive and negative directions of the Z-axis will be referred to as upper and lower sides of the actuator  1 , respectively. 
     In the first embodiment, the fan  40  is described as being an air blower for blowing the external air toward the partitioned space on the side of the guide members  12 . Alternatively, the fan  40  may be an evacuator for drawing the internal air existing in the partitioned space on the side of the guide members  12 . 
       FIG. 2  is a section view taken along line II-II in  FIG. 1B . As shown in  FIG. 2 , the board plate  50  and the control board  60  are arranged around the shaft  11 . More specifically, the board plate  50  and the control board  60  are supported by the posts  24   a  to  24   d  (see  FIG. 1B ) and are arranged above the guide members  12  with a specified gap left therebetween. 
     The partition member  30  is arranged between the board plate  50  and the guide members  12 . More specifically, the partition member  30  is arranged to close the open portion of the frame  20  formed above the guide members  12 . The partition member  30  is made of a material having relatively high heat conductivity, e.g., aluminum, copper or iron. 
     In this manner, the actuator  1  can be configured such that the heat transfer from the control board  60  to the shaft  11  becomes difficult by partitioning the space between the control board  60  and the shaft  11 , i.e., the space between the board plate  50  and the guide members  12 , with the partition member  30 . 
     The partition member  30  can also shield the electric wave noise generated by the control board  60  and the electromagnetic noise generated by the linear motors  10 . By providing the partition member  30 , the actuator  1  can be configured such that it becomes difficult for the electric wave noise generated by the control board  60  to be transferred to the Linear motors  10  and also it becomes difficult for the electromagnetic noise generated by the linear motors  10  to be transferred to the control board  60 . 
     The partition member  30  may be formed by a material having high heat conductivity, such as aluminum, the surface of which is coated with iron powder. This makes it possible to further enhance the effect of shielding the electric wave noise and the electromagnetic noise. This holds true in case where the partition member  30  is formed by an iron plate effective in shielding the electric wave noise and the electromagnetic noise, the surface or which is coated with a material having a high heat conductivity. The partition member  30  may be formed into an arc shape in conformity with the external shape of the fan  40 . 
     The fan  10  is arranged on the side of the guide members  12  with respect to the partition member  30 . The fan  40  is provided to blow, when driven, the external air toward the storage space of the guide members  12  defined by the frame  20  together with the partition member  30  and the fan  40 . 
     The frame  20  has an opening  26  formed at the opposite side of the guide members  12  from the partition member  30 . By driving the fan  40 , the air existing in the storage space is blown to the outside through the opening  26  of the frame  20 . In this manner, the actuator  1  is configured to replace the air existing in the storage space of the guide members  12  with a new air by using the fan  40 , thereby making it possible to suppress a temperature increase in the storage space of the guide members  12 . In addition, the partition member  30  itself can be cooled by the air blown by the fan  40 . 
     Hereinafter, more detail description will be made with reference to  FIG. 3 .  FIG. 3  is a section view taken along line III-III in  FIG. 2 . For the sake of easier understanding, the posts  24   c  and  24   d , the board plate  50  and the control board  60  are omitted in  FIG. 3 . 
     As shown in  FIG. 3 , an axis P 1  of the fan  40  extends substantially parallel to the arranging direction of the guide members  12 , i.e., the Y-axis direction. Further, the axis P 1  of the fan  40  is arranged closer to the partition member  30  than the axes P 2  of the guide members  12 . 
     Accordingly, upon operating the fan  40 , an atmospheric pressure difference is generated between a space on the side of the partition member  30  with respect to the guide members  12  and a space on the side of the opening  26  with respect to the guide members  12 . More specifically, the atmospheric pressure in the space on the side of the partition member  30  with respect to the guide members  12  is higher than the atmospheric pressure in the space on the side of the opening  26  with respect to the guide members  12 . 
     Thus, the air existing in the storage space of the guide members  12  flows from the high atmospheric pressure side toward the low atmospheric pressure side. That is, the air flows from the space on the side of the partition member  30  with respect to the guide members  12  toward the opening  26 . Therefore, the actuator  1  of the first embodiment can efficiently blow the air existing in the storage space of the guide members  12  to the outside through the opening  26 . 
     Further, the guide members  12  are arranged side by side with a specified gap “d” left therebetween. Thus, the air existing in the storage space of the guide members  12  flows toward the opening  26  through the gaps “d” between the guide members With the actuator  1  configured as described above, it is therefore possible to increase the cooling effect of the linear motors  10  as compared with a case where the guide members  12  are arranged in a mutually-contacting state. 
     As shown in  FIGS. 2 and 3 , a cutout portion  23   a  conforming to the shape of a blowing hole  41  of the fan  40  is formed in the sidewall portion  23  of the frame  20  provided between the guide members  12  and the fan  40 . As a result, the air blown by the fan  40  is brought into direct contact with the guide members  12 . This makes it possible to increase the cooling effect of the guide members  12 . The cutout portion  23   a  may not be formed. 
     In this manner, the actuator  1  of the first embodiment can be configured to suppress a temperature increase around the shaft  11  by blowing the air existing in the storage space of the guide members  12  by using the fan  40 . 
     Further, in the first embodiment, one opening  26  is formed in the storage space of the guide members  12 . However, in addition to the opening  26 , another opening may be formed in the storage space of the guide members  12 . 
     For example, as shown in  FIG. 3 , the opposite side of the storage space of the guide members  12  from the fan  40  is kept closed by a cover body  70  in the actuator  1 . Alternatively, the actuator  1  may not be provided with the cover body  70 . That is to say, the opposite side of the storage space of the guide members  12  from the fan  40  may be opened just like the opening  26 . 
     Next, the configuration of each of the linear motors  10  will be described with reference to  FIGS. 4A and 4B .  FIG. 4A  is a section view taken along line IVA-IVA in  FIG. 3 .  FIG. 4B  is a section view taken along line IVB-IVB in  FIG. 4A . 
     As shown in  FIG. 4A , each of the linear motors  10  includes the shaft  11  and the guide member  12 . The shaft  11  is a cylindrical columnar member and has a permanent magnet  90  arranged on the circumferential surface thereof. The permanent magnet  90  is arranged in an opposing relationship with a coil  80  to be described later (see  FIG. 4B ). 
     The shaft  11  is linearly movably supported by a linear movement bearing  25   a  such as a linear bearing arranged in the third support portion  25 . The shaft  11  is an example of a movable member. 
     The guide member  12  is a tubular member. The coil  80  having a tubular shape is fixed to the inner circumferential surface of the guide member  12  by molding or bonding. The guide member  12  serves as a magnetic path of magnetic flux generated from the permanent magnet  90 . For that reason, the guide member  12  is made of a magnetic material such as iron or the like. The guide member  12  is an example of a stator. 
     The guide member  12  is formed into a tubular shape as mentioned above. Therefore, the air resistance of the guide member  12  is smaller than the air resistance of, e.g., guide member having a prismatic shape. Accordingly, the guide member  12  is more easily cooled by the air blown from the fan  40  compared with the guide member having a prismatic shape. By providing the guide member  12  having a tubular shape, the actuator  1  can enable the air blown from the fan  40  to reach the inner side of the storage space of the guide member  12  with ease. 
     As shown in.  FIG. 4B , the guide member  12  has a protruding portion  121  protruding in the positive direction of the Z-axis, i.e., toward the partition member  30 . By forming such protruding portion  121 , a specified space R is formed between the inner circumferential surface of the guide member  12  and the coil  80 . The specified space R is a space that accommodates, e.g., a bolt screw  100  for fixing the guide member  12  to the first support portion  21 . The specified space R serves also as a space for accommodating a jumper wire  81  of the coil  80 . 
     The surface area of the guide member  12  is increased by forming the protruding portion  121 . Thus, it becomes easy to dissipate heat as compared with a case where the guide member  12  is not provided with the protruding portion  121 . In this manner, since the guide member  12  has the protruding portion  121  serving as a fin, the cooling effect thereof can be increased. Further, since the coil  80  makes close contact with the guide member  12 , the heat of the coil  80  is readily dissipated from the guide member  12 . 
     As described above, the actuator  1  in accordance with the first embodiment includes the linear motors, the partition member and the fan. Each of the linear motors linearly moves the shaft. The partition member is arranged close to the shaft to partition the space defined between the control board for controlling the linear motors and the shaft. The fan is arranged on the side of the shaft with respect to the partition member and is configured to flow the air existing in the partitioned space on the side of the shaft. With the actuator of the first embodiment, it is possible to suppress a temperature increase around the shaft. 
     (Second Embodiment) 
     In the first embodiment described above, the guide members  12  are arranged at a regular interval “d” (see  FIG. 3 ). However, the guide members  12  may be arranged at different intervals. 
     A case where the intervals between the guide members are varied depending on the distance from the fan  40  will now be described with reference to  FIG. 5 . In the following description, like reference numerals will be given to the same parts as those described in the above and redundant description thereof will be omitted. 
       FIG. 5  is an explanatory view illustrating the case where the intervals between guide members are varied depending on the distance from the fan. In  FIG. 5 , among the linear motors included in the actuator  1   a , three linear motors arranged closest to the fan  40  are designated by reference numerals  10   a ,  10   b  and  10   c  in the order of distance from the fan  40 . Further, among the linear motors included in the actuator  1   a , two linear motors arranged farthest from the fan  40  are designated by reference numerals  10   d  and  10   e  in the order of distance from the fan  40 . 
     As shown in  FIG. 5 , the linear motors  10   a  to  10   e  are respectively provided with guide members  12   a  to  12   e . In the second embodiment, the actuator la is configured such that the intervals between the guide members  12   a  to  12   e  are adjusted to be gradually increased as the distance from the fan  40  is increased. 
     More specifically, the actuator la includes interval adjustment members  14   a  and  14   b  for adjusting the intervals between the guide members  12   a  to  12   e . The interval adjustment members  14   a  and  14   b  may be made of, e.g., a resin. 
     For example, the interval adjustment members  14   a  are members for narrowing the interval between the guide members  12   a  and  12   b . The interval adjustment members  14   a  are respectively arranged on a surface of the guide member  12   a  opposite to the guide member  12   b  and a surface of the guide member  12   b  opposite to the guide member  12   a . Therefore, the interval between the guide members  12   a  and  12   b , i.e., the interval between the interval adjustment members  14   a,  becomes equal to “d 1 ” which is smaller than the interval “d” (see  FIG. 3 ) between the guide members  12   a  and  12   b  available when the interval adjustment members  14   a  are not provided. 
     The interval adjustment members  14   b  are members for narrowing the interval, between the guide members  12   b  and  12   c.  The adjustor members  14   b  are respectively arranged on a surface of the guide member  12   b  opposite to the guide member  12   c  and a surface of the guide member  12   c  opposite to the guide member  12   b . Therefore, the interval between the guide members  12   b  and  12   c , i.e., the interval between the interval adjustment members  14   b , becomes equal to “d 2 ” which is smaller than the interval “d” (see  FIG. 3 ) between the guide members  12   b  and  12   c  available when the interval adjustment members  14   b  are not provided. The interval “d 2 ” is larger than the interval “d 1 ” between the guide members  12   a  and  12   b.    
     No interval adjustment member is provided between the two guide members  12   d  and  12   e  arranged farthest from the fan  40 . Accordingly, the interval “d” between the guide members  12   d  and  12   e  is larger than the interval ″d 2 ″ between the guide members  12   b  and  12   c.    
     In the second embodiment, as described above, the actuator  1   a  can be configured such that the intervals between the guide members  12   a  and  12   b , and between the guide members  12   b  and  12   c  are adjusted to be increased as the distance from the fan  40  is increased. As a result, a flow rate of the air is reduced when passing through the gaps between the guide members positioned closer to the fan  40 . On the other hand, the flow rate of the air is increased when passing through the gaps between the guide members positioned farther from the fan  40 . 
     Since the fan.  40  is arranged at one end of the arranging direction of the guide members  12   a  to  12   e , there may possibly be generated a deviation in the effect of cooling the guide members  12   a  to  12   e  with the fan  40 . For example, in case of the actuator la shown in  FIG. 5 , the air blown from the fan  40  is easy to make contact with the guide member  12   a  positioned closest to the fan  40 . The air blown from the fan  40  is hard to make contact with the guide member  12   e  positioned farthest from the fan  40 . Therefore, it is likely that the guide member  12   e  is hard no be cooled compared to the guide member  12   a.    
     In the second embodiment, the intervals between the guide members  12   a  to  12   e  are adjusted to be increased as the distance from the fan  40  is increased, thereby increasing the flow rate of the air passing through the gaps between the guide members positioned farther from the fan  40 . This makes it possible to reduce a deviation in the cooling effect, which may be generated between the guide members  12   a  to  12   e.    
     Referring again to  FIG. 5 , the respective guide members  12   a  to  12   e  are arranged such that intervals S between the axes P 3  remain constant. Therefore, in the second embodiment, the intervals between the guide members  12   a  to  12   e  are differently set while the intervals between the axes P 3  of the guide members  12   a  to  12   e , i.e., the intervals between the shafts are maintained constant. Therefore, the actuator la of the second embodiment does not suffer from the impairment of controllability as compared with a typical actuator in which a plurality of guide members is arranged at a regular interval. 
     While the foregoing description is directed to the case where the intervals between the guide members  12   a . to  12   e  are adjusted to be gradually increased as the distance from the fan  40  is increased, the intervals between the guide members  12   a  to  12   e  may be adjusted in a stepwise manner. For example, in  FIG. 5 , there is shown the case where the intervals between the guide members  12   a  to  12   e  are gradually increased in the order of d 1 , d 2 , . . . , d from the fan  40 , but the interval between the guide members  12   a  to  12   e  may be increased stepwise in the order of, e.g., d 1 , d 1 , d 2 , d 2 , and so forth. 
     In the second embodiment, as described above, the intervals between the guide members are set such that the interval (e.g., the interval “d”) between the neighboring guide members (e.g., the guide members  12   d  and  12   e ) arranged farther from the fan becomes larger than the interval (e.g., the interval “d 1 ”) between the neighboring guide members (e.g., the guide members  12   a  and  12   b ) arranged closer to the fan. With such configuration, it is therefore possible to reduce a deviation in the cooling effect generated between the guide members and to equally cool the guide members. 
     (Third Embodiment) 
     While the first embodiment described above is directed to the case where the heat generated from the control board  60  is shielded by the partition member  30 , heat dissipating portions may be provided on the partition member in order to increase the heat dissipating effect of the partition member. A case where fins are provided on the partition member will now be described by way of example with reference to  FIG. 6 .  FIG. 6  is an explanatory view illustrating the case where fins are provided on the partition member. 
     As shown In  FIG. 6 , the actuator  1   b  of the third embodiment includes a partition member  30   a  in place of the partition member  30  of the actuator  1  of the first embodiment. The partition member  30   a . includes fins  31  arranged on a surface thereof facing the board plate  50 . By providing the fins  31 , it becomes easy to dissipate heat accumulated in the partition member  30   a . This makes it difficult for the heat to be transferred to the space on the side of the guide members  12  with respect to the partition member  30   a . Accordingly, it is possible to further suppress a temperature increase around the shaft  11 . 
     While the fins  31  are provided on the surface of the partition member  30   a  facing the board plate  50  in the present embodiment, it may be possible to arrange the fins on the surface of the partition member facing the guide members. Further, while the partition member  30   a  is provided with the fins  31  as an example of the heat dissipating member in the present embodiment, the partition member may be provided with other heat dissipating members such as a heat pipe and the like. 
     In the third embodiment, as described above, the partition member is provided with the heat dissipating portions for dissipating heat. It is therefore possible to further suppress a temperature increase around the shaft. 
     In the above-described embodiments, the actuator having a plurality of linear motors arranged in a single row has been described as an example of the actuator. However, the actuator may be provided with linear motors arranged in multiple rows. 
     Further, in the above-described embodiments, the drive device formed of the linear motor has been described. However, the drive device is not limited to the linear motor. As an alternative example, the actuator may be configured to include, as the drive device, the combination of a rotary motor and a ball screw. The ball screw is a linear movement mechanism for linearly moving the shaft. In this case, a nut threadedly coupled to the ball screw and connected to the shaft corresponds to a movable member. A guide rail for linearly moving the nut corresponds to a guide member. 
     Further, while the heat dissipating portions are provided in the partition member in the third embodiment described above, the actuator may further include, e.g., heat dissipating portions arranged on the lower surface of the board plate. 
     Other effects and modified examples can be readily derived by those skilled in the art. For that reason, the broad aspect of the actuator and the actuator cooling method are not limited to the specific disclosure and the representative embodiments shown and described above. Accordingly, the actuator and the actuator cooling method can be modified in many different forms without departing from the spirit and scope of general inventive concept defined by the appended claims and the equivalents thereof.