WO2016063353A1

WO2016063353A1 - Motor control device and robot system

Info

Publication number: WO2016063353A1
Application number: PCT/JP2014/077975
Authority: WO
Inventors: 祖田　龍一; 健一貞包; 頭國尾形
Original assignee: 株式会社安川電機
Priority date: 2014-10-21
Filing date: 2014-10-21
Publication date: 2016-04-28

Abstract

[Problem] To reduce the size of a motor control device and yet ensure the rigidity of a housing. [Solution] A motor control device 1, which controls a motor M, has: a housing 2 which is equipped with a plurality of sets of opposing wall sections such as a front wall section 2a and a rear wall section 2b; and a plurality of strength members F1, F2, F3 which are amplifier substrates 32, 34 and a DB substrate 36 that are coupled to shield plates 12, 14 and a resistance module RM that are disposed respectively opposing the substrates 32, 34, 36. The strength members F1, F2, F3 are disposed extending between the opposing front wall section 2a and rear wall section 2b and partition the internal space of the housing 2.

Description

Motor control device and robot system

The disclosed embodiment relates to a motor control device and a robot system.

Patent Document 1 describes a robot control device in which a motor driver, wiring, heat dissipating fins, a cooling fan, and the like in which various circuit elements such as a servo amplifier are mounted are provided inside a casing.

JP 2007-144590 A

In the above prior art, when the rigidity of the casing is increased, it may be possible to provide a separate strength member, but this may be a factor that hinders downsizing of the control device. Therefore, further optimization of the device configuration is desired in order to reduce the size while ensuring the rigidity of the housing.

The present invention has been made in view of such problems, and an object thereof is to provide a motor control device and a robot system that can be miniaturized while ensuring the rigidity of the casing.

In order to solve the above-described problem, according to one aspect of the present invention, a motor control device for controlling a motor, a housing including a plurality of sets of opposing wall portions, a first substrate, and the first substrate A motor control device having a plurality of strength members that are connected to opposing plate-like members and are arranged between the opposing wall portions to partition the internal space of the housing is applied. .

Also, according to another aspect of the present invention, a robot system including the motor control device and a robot controlled by the motor control device is applied.

According to still another aspect of the present invention, there is provided a motor control device for controlling a motor, wherein a housing having a plurality of sets of opposing wall portions, and a substrate disposed in the housing are provided in the housing. A motor control device having means for use as a strength member is applied.

According to the present invention, the motor control device and the robot system can be reduced in size while ensuring the rigidity of the casing.

1 is a circuit configuration diagram illustrating an example of a circuit configuration of a motor control device according to an embodiment. It is a perspective view showing an example of the structure of a motor control device. It is a top view showing an example of the structure of a motor control device. It is a front view showing an example of the structure of a motor control device. It is a perspective view showing an example of the structure of a resistance module. It is a top view showing an example of the main board comprised with a plurality of boards. It is sectional drawing by the XX cross section of FIG. It is explanatory drawing showing an example of the robot system provided with the motor control apparatus and robot which concern on one Embodiment.

Hereinafter, an embodiment will be described with reference to the drawings. In the following, for convenience of explanation, directions such as “front”, “rear”, “left”, “right”, “upper”, “lower”, etc. may be described, but these directions are directions noted in the drawings. Correspond to each. However, these descriptions do not limit the positional relationship of each component such as the motor control device.

<1. Circuit configuration of motor control device>
First, an example of a circuit configuration of the motor control device of the present embodiment will be described with reference to FIG.

As shown in FIG. 1, the motor control device 1 converts electric power input from an external power source into predetermined electric power and outputs it to a load. Specifically, the motor control device 1 converts AC power input from the three-phase AC power source 100 into another AC power, for example, eight three-phase AC motors M1, M2, M3, M4, M5, M6. M7 and M8 (hereinafter collectively referred to as “motor M”) to control the operation. That is, the motor control device 1 is a motor control device capable of 8-axis control.

The number of axes that can be controlled by the motor control device 1, that is, the number of motors M is not limited to eight, and may be any other number. Further, the external power source is not limited to the three-phase AC power source, and may be another power source. Further, the load is not limited to the three-phase AC motor, and may be another load.

The motor control device 1 includes a diode module DM, for example, four capacitors C1, C2, C3, C4 (hereinafter collectively referred to as “capacitor C”), for example, eight power modules PM1, PM2, PM3, PM4, PM5, PM6. PM7 and PM8 (hereinafter collectively referred to as “power module PM”), a regenerative resistor R which is an example of a resistor, switches Q1 and Q2, and a resistor module RM for dynamic brake, and a plurality of electronic components.

The diode module DM includes a diode, rectifies three-phase AC power input from the AC power supply 100, and outputs DC power to the DC buses P and N. The capacitors C1 to C4 are connected across the DC buses P and N, and smooth the DC voltage rectified by the diode module DM. The power modules PM1 to PM8 are provided with a plurality of switching elements SW (only one is shown in FIG. 1) constituted by semiconductor elements such as IGBTs. Each of the power modules PM1 to PM8 converts DC power into predetermined three-phase AC power and outputs it to the three-phase AC motors M1 to M8. The diode of the diode module DM, the capacitors C1 to C4, the switching elements SW of the power modules PM1 to PM8, and the like constitute the power conversion circuit 10.

Further, a series circuit of the regenerative resistor R and the switch Q1 is connected between the DC buses P and N. The switch Q1 includes a semiconductor element such as a MOSFET, for example. When the switch Q1 is turned on, for example, when the motor M is suddenly decelerated or suddenly stopped, the regenerative power input from the motor M to the DC buses P and N is regenerated. To be consumed by. The regenerative resistor R consumes regenerative power when the switch Q is turned on.

Also, resistors RD1 to RD8 (hereinafter collectively referred to as “resistors RD”) that consume electric power (load energy) generated by the motors M between the power modules PM1 to PM8 and the motors M1 to M8. And the switch Q2 are connected. The resistor RD is connected so as to short-circuit between different phases of the power line of the motor M. The resistor module RM includes eight resistors RD1 to RD8 in this example, and the electric power (load energy) generated by the motor M by the resistor RD corresponding to when each motor M suddenly decelerates or suddenly stops. When consumed, a braking force is applied to the motor M using a so-called dynamic brake. The switch Q2 is normally closed. For example, when the motor M is suddenly decelerated or suddenly stopped, the switch Q2 is disconnected from the motor M and the power module PM, and the electric power generated by the motor M by the resistor RD (load energy) ) To be consumed.

Note that the circuit configuration of the motor control device 1 described above is merely an example, and a circuit configuration other than the above may be used. For example, the number of power modules PM and resistors RD is not limited to eight and may be other numbers. In addition, the present invention is not limited to the case where two power modules PM are connected in parallel to one capacitor C. One power module PM is connected to one capacitor C, or three or more power modules PM are connected in parallel. May be connected. Further, the number of capacitors C is not limited to four, and may be other numbers. A reactor may be installed instead of the capacitor C.

<2. Structure of motor controller>
Next, an example of the structure of the motor control device 1 will be described with reference to FIGS. 2, 3, and 4. 2, the illustration of the upper wall portion and the front wall portion of the housing of the motor control device 1 is omitted, the illustration of the upper wall portion is omitted in FIG. 3, and the front wall portion in FIG. Is omitted. Also, in FIGS. 2 to 4, illustration of components other than the main part of the motor control device 1 is omitted as appropriate.

As shown in FIG. 2 to FIG. 4, the motor control device 1 has a substantially rectangular parallelepiped casing 2 that forms the outline thereof. The casing 2 includes a front wall portion 2a (see FIG. 3), a rear wall portion. 2b, a left wall 2c, a right wall 2d, an upper wall 2e (see FIG. 4), and a lower wall 2f. Hereinafter, in the motor control device 1, the horizontal direction is also referred to as “width direction”, the vertical direction is also referred to as “height direction”, and the front-rear direction is also referred to as “depth direction”. In addition, the shape of the housing 2 is not limited to a substantially rectangular parallelepiped shape, and may be another shape.

The housing 2 includes a main board 30 (an example of a second board), two amplifier boards 32 and 34 (an example of a first board), and a dynamic brake board 36 (hereinafter referred to as a “DB board 36”). An example of the first substrate), two metal shielding plates 12 and 14 (an example of a plate-like member), the diode module DM, the capacitors C1 to C4, the power modules PM1 to PM8, the regenerative resistor R, and the resistor A plurality of electronic components including the module RM, three

heat sinks

50, 52, and 54, a fan 60, and the like are accommodated. In addition, two ventilation openings 4 and 6 are formed in the housing 2.

(2-1. Substrate)
The main board 30 has a substantially rectangular shape, and the dimension in the plate surface direction is substantially equal to the inner dimension of the lower wall portion 2 f of the housing 2. As for the main board | substrate 30, the one side surface is the component surface 30a in which components are arrange | positioned, and the other side surface is the solder surface 30b in which soldering is performed. The main board 30 is disposed adjacent to the lower wall part 2f (an example of one wall part) at the lower part in the housing 2 such that the component surface 30a is the upper surface and the solder surface 30b is the lower surface. It is fixed to the lower wall portion 2f. The main board 30 is composed of a plurality of boards (details will be described later, see FIG. 6).

The

amplifier boards

32 and 34 are erected on the component surface 30a of the main board 30 so as to face each other via a connector or the like (not shown). Specifically, each of the

amplifier boards

32 and 34 has a substantially rectangular shape, and each dimension in the longitudinal direction is substantially equal to the inner dimension in the depth direction of the casing 2, and each dimension in the short side direction is that of the casing 2. A little smaller than the inner dimension in the height direction. The

amplifier boards

32 and 34 are arranged in the width direction of the main board 30 so that each longitudinal direction is along the depth direction and each short side direction is along the height direction, while being spaced apart by a predetermined gap in the width direction. In the vicinity of the central portion, they are arranged to face each other substantially in parallel. That is, in the

amplifier boards

32 and 34, the right surface 32a of the amplifier board 32 and the left face 34a of the amplifier board 34 are disposed to face each other in the width direction. Hereinafter, the right surface 32a is also referred to as “opposing surface 32a”, and the left surface 34a is also referred to as “facing surface 34a”.

The DB board 36 is erected on the component surface 30a of the main board 30 via a connector or the like (not shown). Specifically, the DB substrate 36 has a substantially rectangular shape, and its longitudinal dimension is smaller than the inner dimension in the depth direction of the

amplifier substrates

32 and 34. In this example, the heat sink base 501 of the heat sinks 50 and 52 described later is used. , 521 have the same size as the longitudinal dimension. The dimension in the short direction of the DB substrate 36 is substantially the same as the short dimension of the

amplifier boards

32 and 34. The DB substrate 36 is disposed substantially parallel to the amplifier substrate 34 on the right side of the amplifier substrate 34 while the longitudinal direction is along the depth direction and the short side direction is along the height direction. The above-described resistance module RM is disposed on the surface (in this example, the left surface) of the DB substrate 36. Details of the resistance module RM will be described later (see FIG. 5).

Note that the shapes and dimensions of the main board 30, the

amplifier boards

32 and 34, and the DB board 36 are not limited to the above-described shapes and the like. The main board 30 does not have to be a plurality of boards, and may be a single board. On the other hand, the

amplifier substrates

32 and 34 and the DB substrate 36 do not have to be a single substrate, and may be composed of a plurality of substrates. The main board 30 is not limited to a single-sided board, and may be a double-sided board in which components are arranged on both sides, a multilayer board in which a plurality of boards are stacked, or the like. Further, the DB substrate 36 may be arranged not on the right side of the amplifier substrate 34 but on the left side of the amplifier substrate 32.

(2-2. Shielding plate)
The shielding

plates

12 and 14 are metal plate members that shield noise generated in the power modules PM1 to 8 and the like disposed along the

amplifier substrates

32 and 34. The shielding

plates

12 and 14 have a substantially rectangular shape, and the longitudinal dimension of each of the shielding

plates

12 and 14 is substantially equal to the longitudinal dimension of the

amplifier boards

32 and 34, and the lateral dimension is the same as the lateral dimension of the

amplifier boards

32 and 34. Almost equal. The shielding plate 12 is arranged in the vicinity of the left side of the amplifier substrate 32 so that the amplifier substrate 32 is on the inner side in the width direction, and the shielding plate 14 is on the right side of the amplifier substrate 34 so that the amplifier substrate 34 is on the inner side in the width direction. The shielding

plates

12 and 14 are arranged substantially parallel to each other.

The shielding

plates

12 and 14 are both fixed to both the front wall portion 2a and the rear wall portion 2b, which are opposite wall portions of the housing 2. Specifically, the front end portion and the rear end portion of the shielding plate 12 are each provided with a fixing piece 12 a bent in a substantially L shape on the left side, and each fixing piece 12 a is connected to the front wall of the housing 2 by a bolt 13. By being fastened to the part 2a and the rear wall part 2b, the shielding plate 12 is fixed to the front wall part 2a and the rear wall part 2b. Similarly, at the front end portion and the rear end portion of the shielding plate 14, fixing pieces 14 a bent in a substantially L shape are provided on the right side, and the fixing pieces 14 a are respectively connected by bolts 15 to the front wall portion 2 a of the housing 2. The shielding plate 12 is fixed to the front wall 2a and the rear wall 2b by being fastened to the rear wall 2b.

The shielding plate 12 is also fixed to the left wall 2c of the housing 2. Specifically, the shielding plate 12 includes a fixed piece 12c at an upper portion that is substantially the same depth position as a rear end portion of a heat sink base 541 described later. The fixed piece 12 c is formed in a shape bent in a stepped shape so as to contact the lower surface of the left end portion of the heat sink base 541 and to contact the upper surface of the right end portion of the bracket 22. As shown in FIG. 4, the bracket 22 is a frame that extends horizontally in the left-right direction, and has a fixed piece 22 a bent in a substantially L shape at the left end. The bracket 22 is supported by the left wall portion 2 c by fixing the fixing piece 22 a to the left wall portion 2 c of the housing 2 by the bolt 21. The fixing piece 12 c of the shielding plate 12 is fixed by the bolt 19 at the overlapping portion with the heat sink base 541 and is fixed by the bolt 20 at the overlapping portion with the bracket 22. Thereby, the bracket 22 connects the shielding plate 12 and the left wall portion 2c of the housing 2 facing the shielding plate 12. As a result, the shielding plate 12 is fixed to the left wall 2c.

Similarly, the shielding plate 14 is also fixed to the right wall 2d of the housing 2. Specifically, the shielding plate 14 includes a fixed piece 14 c at an upper portion substantially the same depth as the rear end portion of the heat sink base 541. The fixing piece 14 c is formed in a shape bent in a stepped shape so as to contact the lower surface of the right end portion of the heat sink base 541 and to contact the upper surface of the left end portion of the bracket 24. As shown in FIG. 4, the bracket 24 is a frame that extends horizontally in the left-right direction, and has a fixed piece 24 a that is bent in a substantially L shape at the right end. The bracket 24 is supported by the right wall portion 2d by fixing the fixing piece 24a to the right wall portion 2d of the housing 2 by a bolt 27. The fixing piece 14 c of the shielding plate 14 is fixed by the bolt 25 at the overlapping portion with the heat sink base 541 and is fixed by the bolt 26 at the overlapping portion with the bracket 24. Thereby, the bracket 24 connects the shielding plate 14 and the right wall 2d of the housing 2 facing the shielding plate 14. As a result, the shielding plate 14 is fixed to the right wall 2d.

Note that the structure for fixing the shielding

plates

12 and 14 to the housing 2 is not limited to the above structure. For example, you may fix the

shielding plates

12 and 14 to wall parts other than the above, for example, the upper wall part 2e, the lower wall part 2f, etc. FIG. In addition, the shape, arrangement, number, and the like of each of the fixed pieces described above are examples, and may be other than the above.

(2-3. Ventilation openings and fans)
As shown in FIG. 3, the vent hole 4 is formed in the vicinity of the center portion in the width direction of the front wall portion 2a so as to be disposed between the

amplifier boards

32 and 34 in the width direction. Similarly, the ventilation opening 6 is formed in the width direction center part vicinity of the rear wall part 2b so that it may be arrange | positioned between amplifier board |

substrates

32 and 34 in the width direction. That is, the ventilation openings 4 and 6 are arranged to face each other in the depth direction, and communicate with a wind tunnel 70 (see FIG. 4) in the housing 2 to be described later.

Note that a plurality of ventilation openings 4 and 6 may be provided. Moreover, you may form the ventilation openings 4 and 6 in wall parts other than the front wall part 21a and the rear wall part 21b.

The fan 60 is disposed inside the ventilation opening 6 between the

amplifier boards

32 and 34, and is provided with a cooling flow path 75 for cooling the power modules PM1 to PM8, the capacitors C1 to C4, and the regenerative resistor R (two in FIG. 4). The air is blown to the wind tunnel 70 (see the dashed line in FIG. 4) including the dotted line. The wind tunnel 70 and the cooling flow path 75 therein are formed to extend in the depth direction.

Specifically, the fan 60 is an exhaust fan, and uses the ventilation port 4 as an intake port and the ventilation port 6 as an exhaust port, and ventilates the air sucked from the ventilation port 4 into the wind tunnel 70 (inside the casing 2). 6 is exhausted outside the wind tunnel 70 (outside the casing 2). Therefore, when the fan 60 blows air to the wind tunnel 70, air mainly flows from the ventilation opening 4 toward the ventilation opening 6 in the wind tunnel 70.

Note that the fan 60 is not limited to an exhaust fan, and may be an intake fan. Moreover, the fan 60 is not limited to the case where it is installed inside the ventilation hole 6, and may be installed inside the ventilation hole 4, or may be installed outside the ventilation hole. Further, the number of fans is not limited to one and may be two or more. Further, for example, when it is not necessary to perform forced cooling using a fan because the amount of heat generated by the electronic component is not so large, the fan need not be installed.

(2-4. Heat sink, wind tunnel)
The heat sinks 50 and 52 are heat sinks for cooling the power modules PM1 to PM8, and are disposed along the facing

surfaces

32a and 34a of the

amplifier boards

32 and 34. Specifically, the heat sink 50 (an example of a first heat sink, an example of a plate member) is disposed along the facing surface 32a of the amplifier board 32, and the heat sink base 501 on which the power modules PM1 to PM4 are installed; A plurality of fins 502. A heat sink 52 (an example of a first heat sink, an example of a plate member) is disposed along the facing surface 34a of the amplifier board 34, and includes a heat sink base 521 on which the power modules PM5 to PM8 are installed, and a plurality of fins. 522.

The heat sink base 501 has, for example, a substantially rectangular shape, the size in the longitudinal direction is smaller than the size in the depth direction of the

amplifier boards

32 and 34, and the dimension in the short direction is also the dimension in the height direction of the

amplifier boards

32 and 34. Smaller than. The heat sink base 501 is disposed on the opposing surface 32a of the amplifier substrate 32 so as to be substantially parallel to the amplifier substrate 32 so that the longitudinal direction thereof is along the depth direction and the short side direction thereof is along the height direction. It is fixed to the amplifier substrate 32 by a bolt 51 (see FIG. 3) through the spacer SP1. The heat sink base 521 has the same shape and dimensions as the heat sink base 501. The heat sink base 521 is disposed on the opposing surface 34a of the amplifier substrate 34 so as to be substantially parallel to the amplifier substrate 34 such that the longitudinal direction thereof is along the depth direction and the short side direction thereof is along the height direction. It is fixed to the amplifier board 34 by a bolt 53 (see FIG. 3) through the spacer SP2.

Further, as shown in FIG. 4, the

heat sink bases

501 and 521 are arranged so that their upper end positions substantially coincide with the upper end positions of the

amplifier boards

32 and 34 in the height direction. In addition, the lower end positions of the

heat sink bases

501 and 521 are slightly below the center in the height direction of the

amplifier boards

32 and 34. In other words, the

heat sink bases

501 and 521 are disposed opposite to each other in the width direction between the

amplifier substrates

32 and 34 on the upper end side thereof. At this time, the arrangement interval of the

heat sink bases

501 and 521 is substantially equal to the diameter of the air blowing part 60 a formed of, for example, an impeller of the fan 60.

In addition, the arrangement | positioning space | interval of the

heat sink bases

501 and 521 is not limited to the case where it is substantially equal to the diameter of the ventilation part 60a of the fan 60, You may be larger or smaller than the said diameter. The

heat sink bases

501 and 521 are not limited to being fixed to the

amplifier boards

32 and 34, and may be fixed to other members. For example, the

heat sink bases

501 and 521 may be fixed to the main board 30, and the

amplifier boards

32 and 34 may be fixed to the

heat sink bases

501 and 521. The

heat sink bases

501 and 521 are not necessarily arranged in parallel with the

amplifier boards

32 and 34. Further, the shape and size of the

heat sink bases

501 and 521 are not limited to the above shape and size, and may be other shapes and sizes.

The plurality of fins 502 protrude from the heat sink base 501 along the width direction, that is, to the right. The plurality of fins 522 protrude from the heat sink base 521 along the width direction, that is, toward the left. That is, the

fins

502 and 522 protrude from the

heat sink bases

501 and 521 in a direction approaching each other.

On the other hand, the heat sink 54 (an example of a second heat sink) is a heat sink that cools the regenerative resistor R. The heat sink 54 is disposed above the

amplifier boards

32 and 34, and includes a heat sink base 541 on which the regenerative resistor R is installed, and a plurality of fins 542.

The heat sink base 541 has a substantially rectangular shape, the size in the longitudinal direction is slightly smaller than the size in the depth direction of the

heat sink bases

501 and 521, and the size in the short direction is larger than the arrangement interval of the

amplifier boards

32 and 34. large. The heat sink base 541 is disposed in parallel with the main board 30 at the upper ends of the

amplifier boards

32 and 34 so that the longitudinal direction thereof is along the depth direction and the short side direction is along the width direction. That is, the heat sink base 541 is disposed opposite to the main substrate 30 in the height direction.

And as shown in FIG. 4, the rear-end part of the heat sink base 541 is fixed to the fixing

pieces

12c and 14c of the shielding

plates

12 and 14 by

bolts

19 and 25. Thereby, the heat sink base 541 connects the upper ends of the shielding

plates

12 and 14. The heat sink base 541 is fixed to the left wall portion 2c and the right wall portion 2d of the housing 2 via the fixing

pieces

12c and 14c and the

brackets

22 and 24.

In addition, the fixing structure between the heat sink base 541 and the housing 2 is not limited to the above structure. For example, the heat sink base 541 may be fixed to a wall portion other than the left wall portion 2c and the right wall portion 2d of the housing 2. Further, it may be fixed to the housing 2 via a member other than the

brackets

22 and 24. Further, the heat sink base 541 is not necessarily arranged in parallel with the main substrate 30. Further, the shape and dimensions of the heat sink base 541 are not limited to the above shapes and dimensions, and may be other shapes and dimensions.

The plurality of fins 542 protrude from the heat sink base 541 toward the main substrate 30 between the

fins

502 and 522, that is, downward. Specifically, the fins 542 protrude from the heat sink base 541 to the vicinity of the upper ends of the capacitors C1 to C4 installed on the component surface 30a of the main board 30.

The wind tunnel 70 is surrounded by the main board 30 and the

amplifier boards

32 and 34 in the housing 2, and a space between the component surface 30 a of the main board 30 and the heat sink base 541 (enclosed by a one-dot chain line in FIG. 4). Space). The fan 60 blows air to the wind tunnel 70.

(2-5. Electronic parts, cooling channel)
The power modules PM1 to PM8 are disposed on the opposing

surfaces

32a and 34a of the

amplifier boards

32 and 34, and are installed on the

heat sink bases

501 and 521, respectively. That is, the power modules PM1 to PM4 connected to each of the capacitors C1 to C4 and the power modules PM5 to PM8 connected to each of the capacitors C1 to C4 are opposed to the opposing

surfaces

32a and 34a of the

amplifier boards

32 and 34, respectively. Are opposed to each other in the width direction.

Specifically, the power modules PM1 to PM4 are arranged on the opposing surface 32a of the amplifier substrate 32 along the plate surface direction of the main substrate 30, that is, along the depth direction, and are installed on the left surface 501a of the heat sink base 501. Has been. The power modules PM1 to PM4 are mechanically and electrically connected to the amplifier board 32 by attaching each of the pin-shaped terminals t to the amplifier board 32 (see FIG. 4). The power modules PM5 to PM8 are arranged on the opposing surface 34a of the amplifier substrate 34 along the plate surface direction of the main substrate 30, that is, along the depth direction, and are installed on the right surface 521a of the heat sink base 521. . The power modules PM5 to PM8 are mechanically and electrically connected to the amplifier board 34 by attaching each of the pin-shaped terminals t to the amplifier board 34 (see FIG. 4).

The capacitors C1 to C4 are arranged along the depth direction on the component surface 30a of the main board 30 between the

amplifier boards

32 and 34. Specifically, the capacitors C1 to C4 have, for example, a substantially cylindrical shape, and the main board 30 protrudes from the main board 30 toward the heat sink 54, that is, upward, between the

heat sink bases

501 and 521. It is installed on the component surface 30a.

As shown in FIG. 3, the capacitors C1 to C4 are disposed between two power modules PM connected to the capacitor C, which are opposed to each other in the width direction. That is, the capacitor C1 is disposed between the power modules PM1 and PM5. The capacitor C2 is disposed between the power modules PM2 and PM6. The capacitor C3 is disposed between the power modules PM3 and PM7. The capacitor C4 is disposed between the power modules PM4 and PM8. The number, arrangement, shape and the like of the capacitors C1 to C4 are not limited to the above contents.

Further, the regenerative resistor R is formed in a plate shape, for example, and is disposed above each of the

amplifier boards

32 and 34 so as to face the component surface 30a of the main board 30. The regenerative resistor R is installed such that its main heat radiating surface Ra is in contact with the upper surface 541 a of the heat sink base 541. Note that the number, arrangement, shape, and the like of the regenerative resistor R are not limited to the above contents.

As shown in FIG. 4, the space surrounded by the heat sink bases 501, 521, 541 and the upper ends of the capacitors C1 to C4 including the space where the

fins

502, 522, 542 are arranged in the housing 2 (see FIG. 4). A space surrounded by a two-dot chain line) forms the cooling flow path 75.

(2-6. Resistance module)
In FIG. 5, an example of the external appearance of DB board | substrate 36 and resistance module RM is shown. In FIG. 5, illustration of mounted components other than the resistance module RM, pattern wiring of the DB substrate 36, and the like is omitted for the sake of complexity.

As shown in FIG. 5, the resistance module RM (an example of a plate-like member) is disposed on the left surface (or right surface) of the DB substrate 36. The resistance module RM is a module formed by modularizing a plurality (8 in this example) of resistors RD1 to RD8 for the dynamic brake described above, and includes a case 37 in which the plurality of resistors RD1 to RD8 are accommodated. The case 37 is made of a metal having a good thermal conductivity such as aluminum. However, the case 37 may be made of a material other than metal (for example, resin). The case 37 is a substantially rectangular plate-like member whose planar shape (the shape seen from the left and right direction) is smaller than that of the DB substrate 36, and has, for example, mounting portions 37a that protrude in the vertical and horizontal directions at the four corners. Yes. The case 37 is attached to the DB substrate 36 by fixing the attachment portions 37 a at the four corners to the corresponding predetermined positions of the DB substrate 36 with bolts 38.

The resistor RD is a flat flat coil and consumes the electric power generated by the corresponding motor M. The plurality of resistors RD are arranged in the case 37 along the front-rear direction, for example, at equal intervals. From the upper end and lower end of the case 37, a plurality (16 in this example) of terminals 39 connected to each resistor RD are led out and connected to the pattern wiring of the DB substrate 36. The case 37 and the terminal 39 are electrically insulated by an insulating member (not shown). The material of the terminal 39 is not particularly limited as long as it is a conductive material. For example, the shape of the terminal 39 can be freely changed by using a flexible electric wire (such as a lead wire or a cable). The influence of the arrangement of parts other than the resistance module RM on the DB substrate 36 and the route of the pattern wiring can be reduced, and the degree of freedom in designing the DB substrate 36 and the resistance module RM can be improved.

The shape and size of the resistance module RM are not limited to the above shape.

(2-7. Strength member of housing)
The motor control device 1 has a plurality (three in this example) of strength members F1 to F3 in the housing 2. Each of the strength members F1 to F3 is a front wall portion facing in the width direction among the three sets of facing wall portions (

wall portions

2a, 2b,

wall portions

2c, 2d, and

wall portions

2e, 2f) of the housing 2. Arranged between 2a (an example of opposing wall portions) and a rear wall portion 2b (an example of opposing wall portions), the internal space of the housing 2 is partitioned in the width direction.

The strength member F1 includes an amplifier substrate 32 and a shielding plate 12 disposed to face the amplifier substrate 32, and further includes a heat sink 50 disposed on the opposite side of the amplifier substrate 32 from the shielding plate 12. . As described above, the amplifier board 32 and the shielding plate 12 are connected to each other by the bolts 17 via the plurality of spacers SP3. Further, as described above, the heat sink 50 is fixed to the amplifier substrate 32 by the bolts 51 via the plurality of spacers SP1. In this way, the strength member F1 in which the amplifier board 32, the shielding plate 12, and the heat sink 50 are connected is configured in the housing 2. The strength member F1 is arranged vertically in the casing 2 along the vertical direction, and the end portions in the front-rear direction are fixed to the front wall portion 2a and the rear wall portion 2b (by the fixing pieces 12a of the shielding plate 12). In addition, the upper end portion is fixed to the left wall portion 2c (by the fixing piece 12c of the shielding plate 12), thereby serving as a strength member that increases the rigidity of the housing 2.

The strength member F2 includes an amplifier substrate 34 and a shielding plate 14 disposed to face the amplifier substrate 34, and further includes a heat sink 52 disposed on the opposite side of the amplifier substrate 34 from the shielding plate 14. . As described above, the amplifier board 34 and the shielding plate 14 are connected to each other by the bolts 18 via the plurality of spacers SP4. Further, as described above, the heat sink 52 is fixed to the amplifier board 34 by the bolts 53 via the plurality of spacers SP2. In this way, the strength member F2 in which the amplifier board 34, the shielding plate 14, and the heat sink 52 are connected is configured in the housing 2. The strength member F2 is arranged vertically in the casing 2 along the vertical direction, and the end portions in the front-rear direction are fixed to the front wall portion 2a and the rear wall portion 2b (by the fixing pieces 14a of the shielding plate 14). In addition, the upper end portion is fixed to the right wall portion 2d (by the fixing piece 14c of the shielding plate 14), thereby serving as a strength member that increases the rigidity of the housing 2.

The strength member F3 includes a DB substrate 36 and a resistance module RM arranged to face the DB substrate 36. As described above, the DB substrate 36 and the resistance module RM are connected to each other by the bolts 18 via the plurality of spacers SP4. In this way, the strength member F3 in which the DB substrate 36 and the resistance module RM are connected is formed in the housing 2.

The bracket 24 includes a recess 28 cut out from the front side at a position corresponding to the DB substrate 36 between the shielding plate 14 and the right wall 2d of the housing 2. The bracket 24 supports the rear end and upper end of the DB substrate 36 by fitting the rear end of the DB substrate 36 into the recess 28. In other words, the DB substrate 36 is connected to the shielding plate 14 via the bracket 24 and to the right wall 2d of the housing 2.

With the above configuration, the strength member F3 is arranged vertically in the casing 2 along the vertical direction, and the rear end portion (by the concave portion 28 of the bracket 24) is located on the strength member F2 and the right wall portion 2d. By being fixed, it serves as a strength member that increases the rigidity of the housing 2.

The structure for fixing the strength member F3 to the housing 2 is not limited to the above structure. For example, the case 37 may be fitted to the bracket 24 instead of the DB substrate 36, or the case 37 may be directly fixed to the wall portion of the housing 2 without using the bracket.

In the present embodiment, the case where the motor control device 1 has the three strength members F1 to F3 will be described as an example. However, the number of strength members is not limited to three, but one, two, or four or more. It is good.

Since the strength members F1 to F3 all have the

substrates

32, 34, and 36, the strength members F1 to F3 are examples of means for using the substrate disposed in the housing 2 as the strength member of the housing 2. It corresponds to.

(2-8. Main board configuration)
Next, an example of the configuration of the main board 30 will be described with reference to FIGS. 6 and 7. In FIG. 6, illustration of mounted components, pattern wiring, and the like is omitted for the sake of complexity.

As shown in FIG. 6, the main board 30 includes a plurality of boards arranged separately, in this example, a control board 41 and a power board 42. The control board 41 is, for example, a substantially L-shaped board, and the power supply board 42 is, for example, a substantially L-shaped board. The control board 41 and the power supply board 42 are arranged so as to form a main board 30 having a rectangular shape as a whole.

Control electronic components (not shown) are mounted on the control board 41. A power supply electronic component (not shown) is mounted on the power supply board 42. The aforementioned four capacitors C1, C2, C3, and C4 are installed on the power supply board. The control board 41 is fixed to a base 48 (see FIG. 7) on the lower wall portion 2f of the housing 2 by driving a plurality of fasteners 47a such as rivets into predetermined positions. Similarly, the power supply board 42 is fixed to the base 48 by driving a plurality of fasteners 47b such as rivets at predetermined positions. Further, the control board 41 and the power supply board 42 are electrically connected by a connector 45 that is mounted across the both.

The

amplifier boards

32 and 34 are both disposed across the control board 41 and the power supply board 42. Specifically, the amplifier board 32 is erected in a state of being electrically connected to the control board 41 and the power supply board 42 via

connectors

43a and 43b. The amplifier board 34 is erected in a state where it is electrically connected to the control board 41 and the power supply board 42 via the

connectors

44a and 44b. That is, the strength member F1 including the amplifier board 32 and the strength member F2 including the amplifier board 34 are erected across the control board 41 and the power supply board 42. In FIG. 6, illustration of the shielding

plates

12 and 14 and the heat sinks 50 and 52 of the strength members F1 and F2 is omitted.

As described above, while the two

amplifier boards

32 and 34 are both disposed across the control board 41 and the power supply board 42, the heat generating components are concentratedly arranged in the central portion (between the amplifier boards 32 and 34) in the left-right direction. In order to consolidate control electronic components on one side in the left-right direction (left side in this example) and collect power electronic components on the other side in the left-right direction (right side in this example), control board 41 and power supply board 42 Is formed in the shape shown in FIG. That is, the gap G between the

boards

41 and 42 is a gap g1 extending in the front-rear direction on the left side of the amplifier board 32, a gap g2 extending in the left-right direction so as to cross the

amplifier boards

32 and 34, and the right side of the amplifier board 34. The

substrates

41 and 42 are formed so as to have a shape having a gap g3 extending in the front-rear direction. In the present embodiment, the gap g2 is positioned closer to the rear in order to ensure the area of the power supply board 42 larger than that of the control board 41 (for example, to secure the installation area of the capacitors C1 to C4).

The strength member F3 including the DB substrate 36 and the resistance module RM is disposed on the power supply substrate 42, and is erected in a state where the DB substrate 36 is electrically connected to the power supply substrate 42 via the connector 46.

Fig. 7 shows the XX cross section of Fig. 6. As shown in FIG. 7, the control board 41 and the power supply board 42 have different plate thicknesses. In this example, the control board 41 is thin and the power supply board 42 is thick. Here, if the control board 41 and the power supply board 42 are arranged so that the positions in the height direction of the surfaces (component surfaces) 41a and 42a on the side where the strength members F1 to F3 are erected are different, In order to connect both the

boards

41 and 42, a dedicated connector having a shape corresponding to the step is required, which leads to an increase in design man-hours and costs. Further, the

connectors

43a and 43b on the amplifier board 32 require connectors having different heights, and the

connectors

44a and 44b on the amplifier board 34 also require connectors having different heights.

In the present embodiment, as shown in FIG. 7, a spacer 49a is inserted between the control board 41 and the base 48 at the place where the fastener 47a of the control board 41 is driven, and the fastener 47b of the power supply board 42 is driven. The height of the control board 41 and the power supply board 42 is adjusted by inserting a spacer 49b between the power supply board 42 and the base 48 at a location. Thereby, the control board 41 and the power supply board 42 are arranged so that the surface 41a and the surface 42a are substantially flush with each other, and in this state, are fixed to the housing 2 via the base 48. As a result, a general-purpose connector can be used as the connector 45 for electrically connecting the control board 41 and the power supply board 42, and the

connectors

43a and 43b and the

connectors

44a and 44b have the same height. Connectors can be used.

Note that the number of substrates constituting the main substrate 30 is not limited to the above two, and may be three or more. Further, the control board 41 and the power supply board 42 may have shapes other than those described above.

<3. Effects of the embodiment>
As described above, the motor control device 1 according to the present embodiment includes the housing 2 including a plurality of sets of opposing wall portions such as the front wall portion 2a and the rear wall portion 2b, the

substrates

32, 34, and 36, and these substrates. A plate-like member (opposed in the above example, shielding

plates

12 and 14, resistance module RM, etc.) arranged opposite to 32, 34, and 36 is connected and arranged between the opposing

wall portions

2a and 2b. It has a plurality of strength members F1, F2, and F3 that partition the internal space of the housing 2. Thereby, there exists the following effect.

That is, the strength members F1, F2, and F3 have a structure in which the

substrates

32, 34, and 36 are connected to the plate-like member, so that each has high strength. Since the strength members F1, F2, and F3 are arranged between the opposing

wall portions

2a and 2b to partition the internal space of the housing 2 into a plurality of small spaces, the rigidity of the housing 2 can be increased. In addition, since the

substrates

32, 34, and 36 are used as strength members, the strength members can be reduced, and the walls 2a to 2f of the housing 2 can be reduced in thickness, so that the motor control device 1 can be reduced in size. Therefore, the housing 2 can be reduced in size while ensuring the rigidity. In addition, as a result of reducing the strength members, there is an effect that it is possible to secure an installation space for a substrate and the like.

In the present embodiment, in particular, the plate members of the strength members F1 and F2 are fixed to both the front wall portion 2a and the rear wall portion 2b facing each other, and the power modules PM and the like disposed on the amplifier boards 32 and 34 ( ) Are

metal shielding plates

12 and 14 for shielding noise generated in the above. Thereby, there exists the following effect.

That is, since the strength members F1 and F2 are configured by connecting the

amplifier boards

32 and 34 and the

metal shielding plates

12 and 14, respectively, high strength can be obtained. Further, it is possible to reduce the noise generated in the

amplifier boards

32 and 34 from affecting the control board and the like.

In the present embodiment, in particular, the two strength members F1 and F2 are arranged to face each other so that the

amplifier boards

32 and 34 are inside the shielding

plates

12 and 14. By arranging in this way, it becomes possible to confine the noise generated in the amplifier boards 32 and 34 (the power module PM and the like arranged in the space) sandwiched between the two shielding

plates

12 and 14. The influence of noise on the control board provided outside can be reduced.

Further, particularly in the present embodiment, the motor control device 1 includes the fan 60 that blows air to the wind tunnel 70 that is a space sandwiched between the

amplifier boards

32 and 34 of the two strength members F1 and F2. As a result, a plurality of heat-generating electronic components (power module PM and the like) disposed on the

amplifier boards

32 and 34 of the two strength members F1 and F2 can be simultaneously and efficiently cooled. Further, since the heat can be confined in a space sandwiched between the two

amplifier boards

32 and 34, it is possible to reduce the influence of the heat on the electronic components and the like provided outside thereof.

In the present embodiment, in particular, the two strength members F1 and F2 include the shielding

plates

12 and 14 and the heat sinks 50 and 52 disposed on the opposite side of the shielding

plates

12 and 14 of the

amplifier boards

32 and 34. It has two plate-like members. Thereby, there exists the following effect.

That is, by connecting the shielding

plates

12 and 14 and the heat sinks 50 and 52 to both sides of each of the

amplifier boards

32 and 34, the strength members F1 and F2 may have a structure in which plate-like members are connected to both sides of the board. Therefore, the strength of the strength members F1 and F2 can be further increased. In addition, since the heat sinks 50 and 52 are arranged in the wind tunnel 70 that is the air blowing space by the fan 60, the cooling efficiency can be further increased.

In the present embodiment, in particular, the motor control device 1 extends in a direction orthogonal to the two strength members F1 and F2, and connects the shielding

plates

12 and 14 of the two strength members F1 and F2. A heat sink 54 is provided. Thereby, the rigidity (for example, the rigidity with respect to a twist, a bending, etc.) of the housing | casing 2 can further be improved. Further, the regenerative resistor R, which is a heat generating component different from the heat generating component disposed on the

amplifier boards

32 and 34, can be simultaneously and efficiently cooled by the heat sink 54.

In the present embodiment, in particular, the motor control device 1 connects the shielding

plates

12 and 14 of the two strength members F1 and F2, and the left wall portion 2c and the right wall portion 2d facing the shielding

plates

12 and 14, respectively.

Brackets

22 and 24 are provided. Thereby, the rigidity (for example, the rigidity with respect to a twist, a bending, etc.) of the housing | casing 2 can further be improved.

In the present embodiment, in particular, the motor control device 1 includes the main board 30 disposed adjacent to the lower wall portion 2 f of the housing 2, and the strength members F <b> 1 and F <b> 2 are erected on the main board 30. The With such a standing structure, the arrangement space of the

amplifier boards

32 and 34 can be greatly reduced, and the motor control device 1 can be downsized.

In the present embodiment, in particular, the main board 30 includes a plurality of control boards 41 and a power supply board 42, and the strength members F1 and F2 are erected across the plurality of

boards

41 and 42. As a result, the plurality of

boards

41 and 42 constituting the main board 30 and each of the

amplifier boards

32 and 34 can be connected to the

connectors

43a and 43b and the connector 44a without using wiring for connecting the

circuit boards

41 and 42. , 44b can be connected directly, so that the wiring in the housing 2 can be reduced.

In the present embodiment, in particular, the control board 41 and the power supply board 42 constituting the main board 30 have different thicknesses, and the control board 41 and the power supply board 42 are provided with strength members F1 and F2. The side surfaces 41a, 42a are arranged so as to be flush with each other. As a result, a general-purpose connector 45 can be used, so that it is possible to prevent an increase in design man-hours and costs.

In the present embodiment, in particular, the plate-like member of the strength member F3 is a resistance module RM including a plurality of resistors RD that respectively consume power generated by a plurality of motors M in a metal case 37. Thereby, there exists the following effect.

That is, since the strength member F3 is configured by connecting the DB substrate 36 and the metal resistance module RM, high strength can be obtained. Further, by consuming the electric power generated by the motor M by the resistor RD, the motor M can be quickly stopped using a so-called dynamic brake. In addition, if the resistors RD corresponding to the number of motor shafts are individually arranged, the size of the motor control device 1 may be hindered due to an increase in the installation area of the resistors RD and cable wiring. In the embodiment, since the plurality of resistors RD are a single module, the installation area of the plurality of resistors RD can be reduced, and the cable wiring can be replaced with the substrate pattern of the DB substrate 36. Can be downsized.

<4. Robot system>
Next, an example of a robot system that controls a robot using the motor control device 1 according to the embodiment will be described with reference to FIG.

As shown in FIG. 8, the robot system 110 includes a motor control device 1 as a robot controller and a robot 120 controlled by the motor control device 1. The robot 120 includes an arm 130. The robot 120 and the motor control device 1 are connected via a cable so that they can communicate with each other. Note that the motor control device 1 may be provided on the robot 120 side, for example, on the arm 130 portion of the robot 120.

The robot 120 is a so-called 6-axis robot. Specifically, the arm 130 of the robot 120 includes a fixed portion 131, a plurality of (in this example, five) link members L1 to L5, and the most proximal end of the arm 130 among these five link members L1 to L5. A plurality of (six in this example) joint mechanisms S1 to S1 that refractably connect the link member L1 positioned on the side and the fixing portion 131 and adjacent link members among the five link members L1 to L5. S6 and actuators A1 to A6 that generate driving force to the link members L1 to L5 to be driven and the six joint mechanisms S1 to S6, respectively. And an elastic member (not shown).

In this example, the actuators A1 to A6 are so-called AC servo motors that are used as power sources for general industrial machines. The actuators A1 to A6 have a stator and a rotor, and output a rotational force. ) At a predetermined reduction ratio, and a speed reducer that amplifies the torque of the motor, and an encoder that detects the rotational position of a rotating body such as a rotating shaft of the motor.

The connection relationship between the stator and rotor of the motor provided in the actuators A1 to A6, the fixed portion 131, and the link members L1 to L6 is as follows. That is, the stator of the motor provided in the actuator A1 is connected to the fixing portion 131, and the rotor of the motor is connected to the link member L1. A stator located on the proximal end side of the arm 130 of the motor provided in the actuator A2 is connected to the link member L1, and a rotor located on the distal end side of the arm 130 of the motor is connected to the link member L2. Similarly, a stator located on the proximal end side of the arm 130 of the motor provided in the actuator A3 is connected to the link member L2, and a rotor located on the distal end side of the arm 130 of the motor is connected to the link member L3. The A stator located on the proximal end side of the arm 130 of the motor provided in the actuator A4 is connected to the link member L3, and a rotor located on the distal end side of the arm 130 of the motor is connected to the link member L4. The stator located on the proximal end side of the arm 130 of the motor provided in the actuator A5 is connected to the link member L4, and the rotor located on the distal end side of the arm 130 of the motor is connected to the link member L5. A stator located on the proximal end side of the arm 130 of the motor provided in the actuator A6 is connected to the link member L5, and a rotor located on the distal end side of the arm 130 of the motor is connected to the link member L6.

In the above description, the case where the motor control device 1 controls a 6-axis robot has been described as an example. However, the robot 120 may be a robot other than 6 axes, such as a 4-axis robot or a 7-axis robot.

In addition, in the above description, when there are descriptions such as “vertical”, “parallel”, and “plane”, the description is not strict. That is, the terms “vertical”, “parallel”, and “plane” are acceptable in design and manufacturing tolerances and errors, and mean “substantially vertical”, “substantially parallel”, and “substantially plane”. .

In addition, in the above description, when there is a description such as “same”, “equal”, “different”, etc., in terms of external dimensions and size, the description is not strict. That is, the terms “identical”, “equal”, and “different” mean that “tolerance and error in manufacturing are allowed in design and that they are“ substantially identical ”,“ substantially equal ”, and“ substantially different ”. .

In addition to those already described above, the methods according to the above embodiments may be used in appropriate combination.

In addition, although not illustrated one by one, the above-described embodiment is implemented with various modifications within a range not departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 2 Case 2a Front wall part (an example of wall part)
2b Rear wall (an example of a wall)
2c Left wall (an example of a wall)
2d right wall (an example of a wall)
2e Upper wall (an example of a wall)
2f Lower wall (an example of a wall)
12 Shield plate (an example of a plate-like member)
14 Shielding plate (an example of a plate-like member)
22 Bracket 24 Bracket 30 Main board (an example of the second board)
32 Amplifier board (example of first board)
34 Amplifier board (example of first board)
36 DB substrate (example of first substrate)
37 Case 41 Control board (an example of a plurality of boards constituting the second board)
41a surface 42 power supply substrate (an example of a plurality of substrates constituting the second substrate)
42a surface 50 heat sink (an example of a first heat sink, an example of a plate member)
52 heat sink (an example of a first heat sink, an example of a plate member)
54 Heat sink (example of second heat sink)
60 Fan 110 Robot system 120 Robot F1 Strength member F2 Strength member F3 Strength member M1 to M8 Motor RD1 to RD8 Resistance RM Resistance module (an example of plate-shaped member)

Claims

A motor control device for controlling a motor,
A housing having a plurality of opposing wall portions;
A plurality of strength members that are connected to the first substrate and a plate-like member disposed to face the first substrate and are arranged between the opposing wall portions to partition the internal space of the housing;
A motor control device comprising:
The plate-like member is
The motor control device according to claim 1, wherein the motor control device is a metal shielding plate that is fixed to both of the opposing wall portions and shields noise generated in the first substrate.
The plurality of strength members are:
3. The motor control device according to claim 2, comprising the two strength members disposed so as to face each other so that the first substrate is inside the shielding plate.
The motor control device according to claim 3, further comprising a fan configured to blow air into a space sandwiched between the first substrates of each of the two strength members.
At least one of the two strength members is
5. The motor control according to claim 3, comprising two plate-like members, the shielding plate and a first heat sink disposed on a side of the first substrate opposite to the shielding plate. apparatus.
6. The heat sink according to claim 3, further comprising a second heat sink that extends in a direction orthogonal to the two strength members and connects the shielding plates of the two strength members. The motor control device according to item.
The motor according to any one of claims 3 to 6, further comprising a bracket that connects the shielding plate of at least one of the two strength members and the wall portion facing the shielding plate. Control device.
A second substrate disposed adjacent to the wall of the housing;
The strength member is
The motor control device according to claim 1, wherein the motor control device is erected on the second substrate.
The second substrate is
It is composed of multiple boards,
The strength member is
The motor control device according to claim 8, wherein the motor control device is erected across the plurality of substrates.
The plurality of substrates constituting the second substrate are:
Includes substrates with different thicknesses,
Substrates with different plate thicknesses
The motor control device according to claim 9, wherein the motor control device is arranged so that a surface on a side where the strength member is erected is flush.
The plate-like member is
The motor control device according to claim 1, wherein the motor control device is a resistance module including a plurality of resistors that respectively consume power generated by the plurality of motors in a metal case.
The motor control device according to any one of claims 1 to 11,
A robot controlled by the motor control device;
A robot system characterized by comprising: