Patent Description:
<CIT> discloses a linear motor, a so-called T-type linear motor, which includes a pair of stators provided along a movement direction so as to face each other and a movable element provided so as to be movable between the pair of stators, and a linear motor driven device for moving a moving body with respect to a substrate using the linear motor as a drive source. Note that, such a linear motor driven device is employed in various devices such as a component mounter for mounting an electronic component on a board or a processing machine as described in <CIT>. As described in <CIT>, the linear motor is configured such that the coil is cooled because thermal deformation and thermal degradation of the component members due to heat generated by the coil are problematic. The coils of a linear motor as described in <CIT> are cooled by thermal conducting pipes having one end inserted between the coils and the other end connected to a metallic heat dissipating plate that may stretch out to behind the stators of the linear motor. <CIT> discloses a three-phase linear motor wherein coils with a U phase, a V phase and a W phase are lined-up in the direction of movement. <CIT> discloses cooling of vertical coils by heat pipes extending vertically from between the coils and provided with heat fins above the coils. <CIT> discloses a linear motor with a heat sink which is connected to the top end of a moving body and which is provided with a radiation fin portion, the heat sink extending horizontally away from the moving body.

However, the configuration for cooling the linear motor as described in <CIT> leaves much room for improvement, and improvements can be applied to enhance the practicality of a linear motor and a linear motor driven device. In view of such circumstances, it is an object of the present disclosure to provide a highly practical method of cooling a linear motor and a highly practical linear motor and linear motor driven device using the cooling method.

A linear motor disclosed in this specification assumes a T-type linear motor as described above. The above-mentioned problems are solved by the invention which is a linear motor as defined in claim <NUM> and a linear motor driven device according to claim <NUM>.

According to the linear motor of the present invention, since the heat dissipator extends to a rear side of one of the pair of stators, the degree of freedom of the cooling structure is increased. Further, in the linear motor driven device of the present invention, the heat dissipator of the cooling member protrudes from a moving body side portion of the movable element and extends to the rear side of the pair of stators through a space between one of the pair of stators and the moving body, such that, compared to a case in which the heat dissipator extends from a portion of the movable member on the opposite to the moving body side, the dimension of the portion that moves together with the moving body in the direction in which the moving body and movable member are lined up can be made smaller. In the linear motor driven device of the present disclosure, since a large thrust force is secured by the T-type linear motor while the size of a dimension in the direction in which the moving body and the movable element are lined up is curtailed, the degree of freedom of attaching to various devices is increased.

Hereinafter, a linear motor and a linear motor driven device according to an embodiment will be described in detail by referring to the drawings. In addition to the embodiments below, various modifications can be made within the scope of the attached claims.

The linear motor and the linear motor driven device of the embodiment are loaded in component mounting device <NUM> shown in <FIG>. Multiple component mounting devices <NUM> are arranged to perform work of mounting multiple types of components onto a board. In <FIG>, two of the multiple component mounting devices <NUM> are shown, and one of these is shown with external panels removed. Component mounting device <NUM> is provided with: base <NUM>; beam <NUM> provided over base <NUM>; board conveyor device <NUM> arranged on the base; multiple component feeders <NUM> removably attached to base <NUM> at a front side of component mounting device <NUM>; component mounting head <NUM> for picking up and holding components supplied from the multiple component feeders <NUM> and mounting the components on board S; and head moving device <NUM> provided on beam <NUM> and configured to move component mounting head <NUM>. Note that, in descriptions below, a direction in which the board is conveyed by board conveyance device <NUM> may be referred to as a left-right direction (X direction), a direction perpendicular to the left-right direction on the horizontal plane may be referred to as a front-rear direction (Y direction), and a direction perpendicular to the left-right direction and the front-rear direction may be referred to as a vertical direction (Z direction).

Reels around which are wound component holding tapes (also referred to as "taped components", which are multiple components held in tape) are set on each of the multiple component feeders <NUM>, and each of the multiple component feeders <NUM> feeds components one by one to a specified component supply position by intermittently feeding the component holding tape.

Component mounting head <NUM> has multiple suction nozzles <NUM>, each of which picks up and holds a component at its lower end by the supply of negative pressure, with the suction nozzles being held by a revolver. The revolver is intermittently rotated, and the suction nozzle <NUM> positioned at a specified position can be raised and lowered by a nozzle raising and lowering device. When the suction nozzle <NUM> at the specified position is lowered, negative pressure is supplied to pick up and hold the component supplied from component feeder <NUM>, and the supply of negative pressure is canceled to mount the component being held on a board. Note that, each of the multiple suction nozzles <NUM> is rotated about its own axis line, such that component mounting head <NUM> can change and adjust the rotational position of the components held by each suction nozzle <NUM>.

Head moving device <NUM> is a so-called XY-type moving device. Head moving device <NUM> includes: head attachment body <NUM> to which component mounting head <NUM> is removably attached; X-direction moving device <NUM> to move head attachment body <NUM> in the X direction; and Y-direction head moving device <NUM> supported by beam <NUM> to move component mounting head <NUM> between component feeders <NUM> and the board by moving X-direction moving device <NUM>. X-direction moving device <NUM> is a linear motor driven device of the present disclosure, and component mounting head <NUM> is moved to any position in the X-axis direction by using linear motor <NUM> as a drive source.

Y-direction moving device <NUM> includes a Y-axis slide <NUM> and moves Y-axis slide <NUM> relative to base <NUM> in the Y direction. Y-direction moving device <NUM> also includes Y-axis guide <NUM> that guides Y-axis slide <NUM> to move in the Y direction. Y-axis guide <NUM> includes a pair of guide rails <NUM> and two sliding members <NUM> slidably engaged with each of the pair of guide rails <NUM>. Further, Y-direction moving device <NUM> includes ball screw <NUM> provided on beam <NUM> and extending in the Y-axis direction, nut <NUM> provided on Y-axis slide <NUM> in a fixed position and rotatably engaged with a ball screw, and motor (servomotor with encoder) <NUM> for rotating ball screw <NUM>.

Next, X-direction moving device <NUM> will be described in detail referring to <FIG> and <FIG>. X-direction moving device <NUM> moves head attachment body <NUM>, as a moving body, by means of linear motor <NUM>, which is a drive source, relative to Y-axis slide <NUM>, as a base. X-direction moving device <NUM> includes pair of X-axis guides <NUM> for guiding head attachment body <NUM> to move in the X direction. X-axis guide <NUM> includes pair of guide rails <NUM> and pair of sliding members <NUM> slidably engaged with each of the pair of guide rails <NUM>. As shown in <FIG>, pair of guide rails <NUM> are fixed to the inner side surface of Y-axis slide <NUM> in parallel in the X direction, and pair of sliding members <NUM> are engaged with guide rails <NUM> in a state fixed to head attachment body <NUM>. According to such a configuration, X-axis guide <NUM> guides head attachment body <NUM> to move in the X direction.

Linear motor <NUM> is a so-called cored T-type linear motor, and includes pair of stators 100a and 100b provided so as to face each other with a space therebetween, and movable element <NUM> moved between the pair of stators 100a and 100b. Each of the pair of stators 100a and 100b includes multiple permanent magnets <NUM>, yoke <NUM> that is a magnetic material to which permanent magnets <NUM> are fixed, and base plate <NUM> which is a non-magnetic material for holding yoke <NUM>. Further, pair of stators 100a and 100b extend in the X-axis direction, and are established on the inner side surface of Y-axis slide <NUM> so as to face each other with a space therebetween in the vertical direction. Note that, multiple permanent magnets <NUM> are alternately arranged in the X direction so that magnetic poles are different from each other on a front surface of each of the pair of stators 100a and 100b, the front surfaces being the surfaces that face other. Also, opposite permanent magnets <NUM> have magnetic poles different from each other.

On the other hand, as shown in the cross sectional view of <FIG>, movable element <NUM> includes cores 120U, 120V, and 120W corresponding to three phases of a U-phase, a V-phase, and a W-phase, and coils 122U, 122V, and 122W wound around cores 120U, 120V, and 120W, respectively. The three-phase cores 120U, 120V, and 120W and coils 122U, 122V, and 122W are arranged side by side in the X-axis direction, which is the movement direction of movable element <NUM>. Note that, the three-phase cores 120U, 120V, and 120W have a cross-shaped cross-sectional shape, and in each of the three-phase coils 122U, 122V, and 122W, the portions wound on the upper side of the cores 120U, 120V, and 120W are referred to as upper portions 124U, 124V, and 124W, and the portions wound on the lower side are referred to as lower portions 125U, 125V, and 125W.

Movable element <NUM> is positioned rearward of the vertical direction extending portion of head attachment body <NUM> as a moving body, and movable element <NUM> and head attachment body <NUM> are fixed via attachment plate <NUM>. In other words, attachment plate <NUM> is provided so as to be parallel to the XZ plane, and head attachment body <NUM> is fixed to the front side of attachment plate <NUM>, and movable element <NUM> is fixed to the rear side of attachment plate <NUM>, thereby fixing movable element <NUM> and head attachment bodying body <NUM>. That is, movable element <NUM> and head attachment body <NUM> are fixed to be adjacent each other in the establishment direction (Y axis direction, front-rear direction) of the pair of stators <NUM>.

Further, X-direction moving device <NUM> includes cooling device <NUM> for cooling linear motor <NUM>. Cooling mechanism <NUM> includes four heat pipes <NUM> and heat sink <NUM> for cooling the heat collected by heat pipes <NUM>. Hereinafter, cooling mechanism <NUM> will be described in detail with reference to <FIG> and <FIG> in addition to <FIG>.

Each of the four heat pipes 142a, 142b, 142c, 142d is inserted, with one end thereof extending in the Y axis direction, between upper portion 124U of U-phase coil 122U and upper portion 124V of V-phase coil 122V, between upper portion 124V of V-phase coil 122V and upper portion 124W of W-phase coil 122W, between lower portion 125U of U-phase coil 122U and lower portion 125V of V-phase coil 122V, and between lower portion 125V of V-phase coil 122V and lower portion 125W of W-phase coil 122W. The one end of each of the four heat pipes <NUM> functions as a heat collector for absorbing the heat of coil <NUM>. Hereinafter, the one end of the four heat pipes <NUM> is sometimes referred to as heat collector <NUM>.

Heat collectors <NUM> of the four heat pipes <NUM> have a flat shape. In other words, the cross-sectional shape of heat collector <NUM> extending in the Y-axis direction is such that the dimension in the movement direction (X-axis direction) is smaller than the dimension in the direction perpendicular to the movement direction (Z direction). Accordingly, in X-direction moving device <NUM>, which is the linear motor driven device of the present embodiment, even if heat collector <NUM> of heat pipes <NUM> is inserted between coils <NUM> of the respective phases in a state in direct contact with coils <NUM> so as to efficiently absorb heat, the size of the dimension in the movement direction of movable element <NUM> is curtailed.

On the other hand, heat dissipator <NUM>, which is the other end portion of each of the four heat pipes <NUM>, protrudes from the head moving body <NUM> side (front side) portion of movable element <NUM>, passes between stator 100a on the upper side and head attachment member <NUM>, and extends above stator 100a. In other words, attachment plate <NUM> is formed with four vertically extending groove plates <NUM>, and heat dissipators <NUM> of the four heat pipes <NUM> extend upward along groove <NUM> of attachment plate <NUM>.

Heat dissipators <NUM> of the four heat pipes <NUM> also have a flat shape. In other words, the cross-sectional shape of heat dissipator <NUM> is such that the dimension extending in the establishment direction (Y-axis direction) of the pair of stators <NUM> is smaller than the dimension in the direction (X-direction) perpendicular to that the direction. To put it another way, the cross-sectional shape of heat dissipator <NUM> extending in the Z-axis direction is such that the dimension (Y direction) perpendicular to the movement direction (X-direction) is smaller than the dimension in the movement direction. That is, X-direction moving device <NUM> that is the linear motor driven device of the present embodiment is configured such that, even if four heat pipes <NUM> pass between the pair of stators <NUM> and head attachment body <NUM>, the gap between the pair of stators <NUM> and head attachment body <NUM> is small, and the size of the dimension in the Y-axis direction including movable element <NUM> and head attachment body <NUM> is curtailed. As described above, each of the four heat pipes <NUM> has a shape in which the directions of the flat surfaces of heat collector <NUM> and heat dissipator <NUM> are different from each other.

Note that, attachment plate <NUM> is made of aluminum having relatively high thermal conductivity, and receives heat from heat dissipators <NUM> of the four heat pipes <NUM> in contact with the attachment plate <NUM> so as to dissipate heat. Further, heat sink <NUM> is provided at an upper end of attachment plate <NUM>. More specifically, heat sink <NUM> includes fins <NUM> having multiple projections formed thereon, and fan <NUM> that air-cools fins <NUM>, and fins <NUM> are fixed to the rear side of the upper end of attachment plate <NUM>, and fan <NUM> is fixed to the rear side of fins <NUM>. That is, fan <NUM>, which is a cooling device, is fixed to movable element <NUM> via attachment plate <NUM> in a state in which fan <NUM> is positioned on the upper of the pair of stators <NUM>, stator 100a, that is, in a state on the upper side of upper stator 100a.

In a cored T-type linear motor, it is common for the cooling mechanism to be arranged side-by-side with respect to the movable member in the establishment direction of the stator. In linear motor <NUM> of the present embodiment, if the cooling mechanism is provided behind movable element <NUM> in the Y-axis direction, the size of the cooling mechanism in the Y-axis direction including movable element <NUM> and head attachment body <NUM> increases. On the other hand, with X-direction moving device <NUM>, which is the linear motor driven device of the present embodiment, heat dissipator <NUM> of heat pipe <NUM>, which is a cooling member, protrudes from the head moving body <NUM> side (front side) of movable element <NUM>, passes between stator 100a on the upper side and head attachment body <NUM>, and extends to the rear side of stator 100a, such that the size of the dimension in the Y-axis direction including movable element <NUM> and head attachment body <NUM> can be curtailed.

Also, with X-direction moving device <NUM>, which is the linear motor driven device of the present embodiment, since heat sink <NUM> including the cooling device is provided by using the space on the rear surface of one of the pair of stators, stator 100a, the effect of cooling linear motor <NUM> is enhanced while curtailing the size of the dimension in the Y-axis direction including movable element <NUM> and head attachment body <NUM>. Note that, although fan <NUM> cannot be used in a magnetic field because a Hall sensor is used, in X-direction moving device <NUM> which is the linear motor driven device of the present embodiment, since yoke <NUM> is disposed between multiple permanent magnets <NUM> and fan <NUM>, fan <NUM> is not affected by the multiple permanent magnets <NUM>, and malfunction or the like of fan <NUM> is prevented.

Claim 1:
A linear motor (<NUM>) comprising:
a pair of stators (100a, 100b) provided along a movement direction so as to face each other;
a movable element (<NUM>) configured to move between the pair of stators (100a, 100b);
a cooling member (<NUM>) having (A) a heat collector (<NUM>) provided inside the moveable element (<NUM>) to absorb heat of the moveable element (<NUM>); and (B) a heat dissipator (<NUM>) protruding outside from the moveable element (<NUM>), and
wherein the cooling member (<NUM>) is a heat pipe (<NUM>) configured such that one end thereof is inserted inside the moveable element (<NUM>) and functions as the heat collector (<NUM>), and another end thereof protrudes outside of the moveable element (<NUM>) and functions as the heat dissipator (<NUM>),
characterized in that
said another end of the heat pipe (<NUM>) that functions as the heat dissipator (<NUM>) extends in the direction in which the pair of stators (100a, 100b) face each other to a rear side of the pair of stators (100a, 100b) and has a cross section shape in which a dimension in a direction perpendicular to the movement direction is smaller than a dimension in the movement direction.