Controller with servo amplifier incorporated in cabinet

A base plate (20) is provided in a standing manner on a center portion of one side surface of a front-surface panel (15), a control unit (3) of a servo amplifier is attached to one surface of the base plate (20), and a heat-radiation unit (19) of the servo amplifier is attached to the other surface. The control unit (3) and other electric parts in a cabinet (11) are connected to each other through a connector cable (9). When the front-surface panel (15) is drawn out to release only the connector cable (9), the control unit (3) and the heat-radiation unit (19) of the servo amplifier can be separated from the cabinet (11).

FIELD OF THE INVENTION
 The present invention relates to an improvement of a controller having a
 servo amplifier built in a cabinet.
 BACKGROUND
 A conventional controller having a servo amplifier built in a cabinet is
 shown in FIGS. 3 and 4.
 A cabinet 1 of the controller is constituted by a rectangular box, and the
 inner space of the box is divided into forward and backward parts by a
 partition plate 2 arranged at the center of the inner space. A rectangular
 opening 5 is formed in the left-side portion of the partition plate 2. In
 addition, mounting bolts (not shown) are provided in a standing manner on
 a front surface of the partition plate 2 near four corners of the
 rectangular opening 5.
 Bolt insertion holes 21 are formed at four corners of a rectangular base
 plate 6 in correspondence with the positions of the mounting bolts. A
 control unit 3 of a servo amplifier is fixed to the front surface of the
 base plate 6, and a heat-radiation unit (not shown) of the servo amplifier
 is fixed to the rear surface. The mounting bolts of the base plate 6 are
 inserted into the bolt insertion holes 21 of the base plate 6, and the
 tops of the mounting bolts are fastened by nuts 7. At this time, the base
 plate 6 is fixed to the partition plate 2 to close the opening 5.
 A numeral control unit 4 is attached to a right-side portion on the front
 surface of the partition plate 2. Therefore, in a state where the base
 plate 6 having the control unit 3 of the servo amplifier attached to the
 front surface and the heat-radiation unit of the servo amplifier attached
 to the rear surface is fixed to the partition plate 2 through the mounting
 bolts and the nuts 7, the control unit 3 of the servo amplifier and the
 numeral control unit 4 are arranged in a forward space partitioned by the
 partition plate 2, and the heat-radiation unit of the servo amplifier is
 arranged in a backward space. An air-blowing fan (not shown) for
 exhausting air heated by heat radiated from the heat-radiation unit of the
 servo amplifier to the outside is arranged in the backward space.
 The control unit 3 of the servo amplifier is connected to other electric
 parts, e.g., the numeral control unit 4, in the cabinet 1 through a
 direct-mounted cable 8 or a connector cable 9. A panel 10 for performing
 maintenance operations for the control unit 3 of the servo amplifier and
 the numeral control unit 4 is attached to the front surface of the cabinet
 1 such that the panel 10 can be freely opened and closed.
 Since a large number of electric parts which are expandable are mounted on
 the control unit 3 and the heat-radiation unit of the servo amplifier,
 maintenance operations for these parts must be performed. For this
 purpose, the control unit 3 and the heat-radiation unit of the servo
 amplifier must be detached out of the cabinet 1, however, when the
 conventional cabinet structure shown in FIG. 3, the opening/closing panel
 10 is opened to take the cables 8 and 9 out, meshing of the nuts 7 for
 fixing the four corners of the base plate 6 is released, so that the
 control unit 3 and the heat-radiation unit of the servo amplifier are
 detached out of the cabinet 1 together with the base plate 6. Such
 cumbersome operations are required.
 DISCLOSURE OF THE INVENTION
 It is an object of the present invention to provide a controller having a
 servo amplifier built in a cabinet, which is capable of easily detaching
 the servo amplifier from the cabinet.
 In order to achieve the above object, in a controller having a servo
 amplifier built in a cabinet, according to the present invention, one
 surface of the cabinet is constituted by a detachable panel, the servo
 amplifier is fixed inside the panel, and the servo amplifier and other
 electric parts arranged in the cabinet are connected through a connector
 cable.
 Preferably, a base plate is provided in a standing manner from an inner
 central portion of the panel, a control unit of the servo amplifier is
 fixed to one surface of the base plate, while a heat-radiation unit of the
 servo amplifier is fixed to the other surface of the base plate, the base
 plate is engaged with a channel-like engagement portion fixed to a
 partition plate for partitioning the space in the cabinet into two spaces
 to form an airtight seal between the two spaces in the cabinet, and a
 air-blowing fan is arranged in a space in which the heat-radiation unit is
 located.
 According to the present invention, without a cumbersome operation such as
 attachment/detachment of screws and nuts, attaching/detaching operation of
 the servo amplifier can be easily performed by only detaching the panel
 constituting one surface of the cabinet. Also, since an arrangement in
 which the control unit and heat-radiation unit of the servo amplifier are
 separated from each other by the partition plate provided in the cabinet
 and the base plate provided in the standing manner on the detachable panel
 is employed, the control unit of the servo amplifier can be prevented from
 being over-heated, dust and dirt carried into the cabinet are prevented
 from penetrating the control unit by the function of the blowing fan
 arranged in the heat-radiation unit.

BEST MODE FOR CARRYING OUT THE INVENTION
 A cabinet 11 of a robot controller, as shown in FIG. 2, is constituted by a
 rectangular box having an opening 17 formed in its front surface, and an
 inner space of the box is divided into left and right spaces by a
 partition plate 12 arranged at a central portion of the inner space. That
 is, the inner space of the cabinet 11 is divided into a left space 11a and
 a right space 11b by the partition plate 12 serving as a boundary as
 viewed from the opening 17.
 In a forward portion of the partition plate 12, i.e., in a portion thereof
 near the opening 17 of the cabinet 11, a rectangular notch is formed. A
 channel-like engagement portion 13 having a groove 13a having a U-shaped
 section extending along the edge of the notch is integrally formed on or
 attached to one surface of the partition plate 12. One end of the
 engagement portion 13 extends up to the front-surface opening 17 of the
 cabinet 11. The engagement portion 13 is desirably formed of an elastic
 material such as hard rubber to achieve dust-proof and moisture-proof
 properties.
 An air-blowing fan and a ventilation hole (not shown) are formed in the
 left space 11a in the cabinet 11, so that air heated in the space 11a can
 be exhausted to the outside.
 The front-surface opening 17 of the cabinet 11 is covered with a
 front-surface panel 15 independent of the cabinet 11. Long holes (not
 shown) extending in lateral direction are formed in four corners of the
 front-surface panel 15. Engagement portions of simple fixtures 16 pass
 through the respective long holes to project from the back surface of the
 front-surface panel 15. The simple fixtures 16 are laterally biased by
 springs (not shown) on the outer side.
 Engagement grooves are formed on the outer sides of the engagement portions
 of the simple fixtures 16 projecting from the back surface of the
 front-surface panel 15. The engagement grooves are engaged, from the
 inside of the contact 11, with the inner folded portions 18 formed around
 the front-surface opening 17 of the cabinet 11. This engagement state is
 held by spring biasing.
 A base plate 20 for attaching the control unit 3 and a heat-radiation unit
 19 (heat sink) of the servo amplifier is provided in a standing manner on
 a center portion of the back surface of the front-surface panel 15. The
 base plate 20 is formed in such a size and a shape that its edge can
 engage with the groove 13a of the engagement portion 13 attached to one
 surface of the partition plate 12 to completely close the rectangular
 notch formed in the forward portion of the partition plate 12.
 The control unit 3 of the servo amplifier is attached to one surface of the
 base plate 20, and the heat-radiation unit 19 is attached to the opposite
 surface. Therefore, in a state where the front-surface panel 15 is
 attached to the cabinet 11, the control unit 3 of the servo amplifier is
 placed in the right space 11b, and the heat-radiation unit 19 is placed in
 the left space 11a. In addition, the inner space of the cabinet 11, as
 described above, is completely separated into the left space 11a and the
 right space 11b by the partition plate 12 and the base plate 20. As a
 result, heat from the heat-radiation unit 19 is prevented from passing
 from the left space 11a to the right space 11b in which the control unit 3
 of the servo amplifier is placed.
 A numeral control unit 4 of a robot controller is arranged at an inner
 position (position where the base plate 20 does not reach) in the right
 space 11b in the cabinet 11.
 In order to attach the front-surface panel 15 to the cabinet 11, the upper
 and lower edges of a distal portion of the base plate 20 are engaged with
 the groove 13a of the engagement portion 13, and the front-surface panel
 15 is pressed into the cabinet 11. Immediately before the front-surface
 panel 15 is brought into contact with the front-surface opening 17, the
 simple fixtures 16 are inwardly pressed with fingers of an operator
 against the biasing forces of the springs, and then the front-surface
 panel 15 is further pressed into the cabinet 11. When the fingers are
 released from the simple fixtures 16 after the front-surface panel 15 is
 brought into contact with the front-surface opening 17,the simple fixtures
 16 move outside by the biasing forces of the springs, and the engagement
 portions of the simple fixtures 16 located on the back surface of the
 front-surface panel 15 move toward the folded portions 18 of the cabinet
 11. As a result, the outside grooves outside the engagement portion are
 engaged with the folded portions 18.
 On the other hand, in order to remove the front-surface panel 15 from the
 cabinet 11, the front-surface panel 15 may be separated from the
 front-surface opening 17 of the cabinet 11 while the simple fixtures 16
 are inwardly pressed with the fingers of the operator against the biasing
 forces of the springs. In this manner, the engagement portions of the
 simple fixtures 16 located on the back surface of the front-surface panel
 15 are retreated from the folded portions 18 of the cabinet 11, and the
 engagement between the outside grooves of the engagement portions and the
 folded portions 18 is canceled. In this state, when the front-surface
 panel 15 is withdrawn, the base plate 20 is removed out of the
 front-surface opening 17 of the cabinet 11 while the base plate 20 is
 guided by the groove 13a of the engagement portion 13.
 To obtain convenience when an operator holds the front-surface panel 15
 with her/his hand to attach or detach the front-surface panel 15 to/from
 the cabinet 11, a handle 14 is fixed on the front surface of the
 front-surface panel 15.
 When the control unit 3 or the heat-radiation unit 19 constituting the
 servo amplifier fails, the control unit 3 and the heat-radiation unit 19
 can be integrally removed together with the front-surface panel 15 by
 inwardly pressing the respective simple fixtures 16 inside to withdraw the
 front-surface panel 15 on the operator's side. Since the connector cable 9
 for connecting the control unit 3 of the servo amplifier and other
 electric parts in the cabinet 1 to each other has a sufficient length, as
 shown in FIG. 2, the control unit 3 of the servo amplifier can be
 completely withdrawn out of the cabinet 11 while the connector cable 9 is
 kept connected, and an operation of removing the connector cable 9 from
 the control unit 3 can also be extremely easily performed outside the
 cabinet 11.
 After a repair operation required for the control unit 3 and/or the
 heat-radiation unit 19, the control unit 3 of the servo amplifier and the
 connector cable 9 are connected to each other again outside the cabinet
 11, the edge of the base plate 20 is fitted in the U-shaped groove 13a of
 the engagement portion 13, and the front-surface panel 15 is directly
 pressed toward the inside of the cabinet 11. At this time, the
 front-surface panel 15 is attached to the cabinet 11 by the simple
 fixtures 16.
 If the above operation must be performed in a hurry, the front-surface
 panel 15 having the disordered control unit 3 and/or heat-radiation unit
 19 is directly set in the repair process, and, in place of this
 front-surface panel, another front-surface panel 15 having a new control
 unit 3 and/or a new heat-radiation unit 19 or another front-surface panel
 15 on which a control unit 3 and/or a heat-radiation unit 19 has already
 been repaired may be prepared to be attached.
 The left space 11a in which the heat-radiation unit 19 of the servo
 amplifier is located and the right space 11b in which the control unit 3
 of the servo amplifier and the numeral control unit 4 are located are
 completely separated from each other by the partition plate 12 and the
 base plate 20, as described above, so that, heat from the heat-radiation
 unit 19 is not transmitted to the control unit 3 and/or the numeral
 control unit 4. Also, since the blowing fan and the ventilation hole are
 provided in the left space 11a in which the heat-radiation unit 19 is
 located to exhaust air warmed in the space 11a to the outside, the
 heat-radiation unit 19 itself is prevented from being overheated.