Linear motor, transport apparatus, and production apparatus

The disclosed linear motor includes a stator having a plurality of cores and coils that excite the plurality of cores, respectively, and a movable element having a permanent magnet and configured to move using electromagnetic force applied from the stator as driving force, each of the plurality of cores has an excitation unit wound with the coil and an acting unit configured to be magnetically coupled to the excitation unit and cause a magnetic flux applied from the excitation unit to work on the permanent magnet of the movable element, and the linear motor includes an airgap or a heat conduction reduction portion between the excitation unit and the acting unit, and the heat conduction reduction portion reduces heat conduction from the excitation unit to the acting unit more than in a case where the excitation unit and the acting unit are in direct contact with each other.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a linear motor, a transport apparatus, and a production apparatus.

Description of the Related Art

A transport apparatus using a moving magnet type linear motor in which magnets are used on a movable element side and coils are used on a stator side does not require connection of a motive power cable on the movable element side and therefore enables long-stroke transportation. Further, such transport apparatuses have no backrush and have high positioning accuracy and repeatability compared to ball screw type transport apparatuses and thus have been used in a high speed transport apparatus used for manufacturing lines for precision instruments. Related arts are disclosed in, e.g., Japanese Patent Application Laid-Open No. 2002-142439 and Japanese Patent Application Laid-Open No. 2009-005516.

In a moving magnet type linear motor, however, a plurality of coils serving as a stator are arranged along a track on which a movable element travels, and controlled drive current is supplied to driving coils to magnetically drive the movable element. Thus, the coils supplied with current in driving generate heat due to Joule heat. In the moving magnet type linear motor, since coils that are heat sources are arranged closer to permanent magnets of a movable element than in the ball screw type transport apparatus, such a linear motor is likely to be affected by a temperature change of the coils. Thus, there is a limit in obtaining precise positioning performance or positioning repeatability. Further, there is a problem of increased fluctuation of a transport speed or inclination of a movable element.

Furthermore, when a circulation type transport apparatus is formed by using a moving magnet type linear motor, a cableveyor (registered trademark) is required for a connection cable used for driving a movable track unit, and generation of dust or disconnection of a cable may occur due to sliding or bending of the connection cable. Thus, suppression of generation of dust is a challenge in application to a manufacturing line for precision instruments.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to provide a compact linear motor and a compact transport apparatus that can suppress influence due to heat generated from coils and realize accurate positioning performance, accurate positioning repeatability, and accurate transport performance. Further, another object of the present invention is to provide a transport apparatus suitable for application to a manufacturing line for precision instruments.

According to one aspect of the present invention, provided is a linear motor including a stator including a plurality of cores and coils that excite the plurality of cores, respectively, and a movable element including a permanent magnet and configured to move using electromagnetic force applied from the stator as driving force, each of the plurality of cores includes an excitation unit wound with each of the coils and an acting unit configured to be magnetically coupled to the excitation unit and cause a magnetic flux applied from the excitation unit to work on the permanent magnet of the movable element, and the linear motor further includes an airgap or a heat conduction reduction portion between the excitation unit and the acting unit, wherein the heat conduction reduction portion reduces heat conduction from the excitation unit to the acting unit more than in a case where the excitation unit and the acting unit are in direct contact with each other.

Further, according to another aspect of the present invention, provided is a transport apparatus including a first transport module forming a stationary track unit, a shifter unit including a second transport module forming a movable track unit and a first movable mechanism that causes the second transport module to move to a first position where the second transport module is connected to the first transport module, and a carriage including a permanent magnet and configured to move using electromagnetic force applied from the first transport module or the second transport module as driving force, and the second transport module includes an acting unit, which is configured to be magnetically coupled to an excitation unit including a coil when the second transport module is located at the first position, and is configured to cause a magnetic flux applied from the excitation unit to work on the permanent magnet of the carriage via the acting unit.

Further, according to another aspect of the present invention, provided is a production apparatus including a stator, a movable element including a permanent magnet, and a chamber, the stator has a plurality of cores and coils that excite the plurality of cores, respectively, each of the plurality of cores includes an excitation unit wound with each of the coils and an acting unit configured to be magnetically coupled to the excitation unit and cause a magnetic flux applied from the excitation unit to work on the permanent magnet of the movable element, the coil and the excitation unit are arranged outside the chamber, and the acting unit is arranged inside the chamber.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

A transport apparatus according to a first embodiment of the present invention will be described with reference toFIG.1AandFIG.1B.FIG.1AandFIG.1Bare sectional views illustrating a general configuration of the transport apparatus according to the present embodiment.

A transport apparatus100according to the present embodiment is a transport apparatus that causes a carriage to travel by using a movable magnet linear motor (a moving magnet type linear motor, a movable field system type linear motor) and thereby transports a workpiece. The transport apparatus100has a transport module210and a carriage220as illustrated inFIG.1AandFIG.1B, for example.

The transport module210forms a track unit (transport path) on which the carriage220travels. Herein, for the purpose of illustration below, coordinate axes are defined for the transport apparatus100. First, the X-axis is defined in the moving direction of the carriage220that moves horizontally. Further, the Z-axis is defined in the perpendicular direction. Further, the Y-axis is defined in the direction orthogonal to the X-axis and the Z-axis. The definition of coordinate axes is the same also in the subsequent embodiments. Note thatFIG.1Ais a sectional view in a plane parallel to the Y-Z plane including a line B-B′ ofFIG.1B. Further,FIG.1Bis a sectional view in a plane parallel to the X-Z plane including a line A-A′ ofFIG.1A.

The transport module210has linear stands102, a plurality of core units230, and a linear guide rails103. The core units230and the linear guide rail103are fixed to the linear stands102.

The plurality of core units230are arranged in a predetermined interval along the moving direction (X-axis direction) of the carriage220and form a stator of the linear motor. Each of the plurality of core units230has a core232and a coil106. The core232has an excitation-side core105, a pair of acting-side cores104provided at both ends of the excitation-side core105, and thermal insulation portions101provided between the acting-side cores104and the excitation-side core105. Note that, althoughFIG.1Billustrates the transport module210having eight core units230arranged in the X-axis direction for simplified illustration of the drawing, the transport module210has a necessary number of core units230for forming a linear motor of any length in the actual implementation.

The pair of the acting-side cores104are arranged to face each other spaced apart from a core gap G and connected and fixed to the linear stands102. The excitation-side core105is connected to the acting-side cores104via the thermal insulation portions101and arranged so as not to be directly connected to the linear stands102. The material of the acting-side core104and the excitation-side core105is not particularly limited, and a magnetic material such as stacked silicon steel plates may be applied thereto, for example.

The coil106is wound around the excitation-side core105of the core232and has a role of exciting the core232. The acting-side cores104are arranged so as to be magnetically coupled to the excitation-side core105, are subjected to a magnetic flux generated by the excitation-side core105, and cause this magnetic flux to work on the movable element arranged in the core gap G. The thermal insulation portion101functions as a heat conduction reduction portion that reduces heat conduction from the excitation-side core105to the acting-side core104more than in a case where the excitation-side core105and the acting-side core104are in direct contact with each other.

Note that, in this specification, the excitation-side core105or the excitation-side cores105of the cores232forming the plurality of core units230may be collectively referred to as an excitation unit. Further, the acting-side core104or the acting-side cores104of the cores232forming the plurality of core units230may be collectively referred to as an acting unit.

The carriage220forms a movable element of the linear motor and has a top plate111, a magnet support112, a permanent magnet113, and linear guide blocks114. The linear guide blocks114are provided at four corners on the under surface of the top plate111so as to be connected to the linear guide rails103when the carriage220is installed on the transport module210. Thereby, the carriage220is supported by the transport module210so as to be movable in the X-axis direction along the linear guide rails103. The magnet support112is fixed to the center part on the under surface of the top plate111such that the permanent magnet113is located in the core gap G between the acting-side cores104when the carriage220is installed on the transport module210. Note thatFIG.1Billustrates a case as an example where an arbitrary skew angle (for example, 20 degrees) is provided to the magnet support112having the same thickness as the permanent magnet113and three permanent magnets113are fixed such that the magnetic poles of adjacent permanent magnets113are opposite alternately.

Each of the coils106of the plurality of core units230is supplied with predetermined current under the control of an upper-level controller (not illustrated). Each of the coils106of the plurality of core units230can be driven in three-phase alternating current made of a U-phase, a V-phase, and a W-phase as labeled with “U”, “V”, and “W” inFIG.1B, for example. When current is applied to the coil106, the permanent magnet113of the carriage220is subjected to electromagnetic force as driving power from the coil106via the excitation-side core105and the acting-side cores104. In such a way, the carriage220obtains driving force and travels on a track unit formed of the linear guide rails103. By appropriately controlling current flowing in each of the coils106of the plurality of core units230, it is possible to cause the carriage220to travel or stop and thereby control the position of the carriage220on the transport module210.

In the moving magnet type linear motor, a plurality of coils serving as a stator are arranged along the track on which a movable element travels, and the movable element is magnetically driven by conduction of controlled drive current to the driving coil. Thus, the conducted coil generates heat during driving due to Joule heat. In the moving magnet type linear motor, since coils that become heat sources are arranged closer to permanent magnets of the movable element than in the ball screw type transport apparatus, the moving magnet type linear motor is likely to be affected by a temperature change of the coils. For example, when the temperature around the permanent magnet changes due to generated heat of the coil, the permanent magnet is demagnetized by thermal energy, and motor thrust may decrease. Thus, the distance between the coil and the permanent magnet of the movable element is required to be increased, and the size of the apparatus increases. Further, if heat of the coil is transferred to a casing or a stand and causes thermal expansion, the position of the sensor arranged in the casing or the stand may change, and this causes a reduction in positioning accuracy.

In this regard, in the transport apparatus according to the present embodiment, each of the cores232of the core unit230forming the stator of the linear motor is formed of the acting-side cores104, the excitation-side core105, and the thermal insulation portions101arranged therebetween as described above. With such a configuration, heat conduction between the excitation-side core105and the acting-side cores104can be suppressed. Further, since the excitation-side core105is not directly connected to the linear stands102, heat of the excitation-side core105is not transferred to the acting-side cores104via the linear stands102. Accordingly, it is possible to effectively suppress heat generated by current flowing in the coil106from being transferred to the acting-side cores104via the excitation-side core105and realize a transport apparatus that can achieve accurate positioning repeatability even with a compact apparatus as a whole.

As the material forming the thermal insulation portion101, a magnetic material having lower thermal conductivity and larger magnetic permeability than the material forming the acting-side core104and the excitation-side core105is desirable. In terms of the above, for example, permalloy, supermalloy, pure iron, amorphous alloy, permendur, sendust, or the like may be preferably used for the material forming the thermal insulation portion101.

The temperature difference ΔT of the thermal insulation portion101between the acting-side core104side and the excitation-side core105side is expressed by Equation (1) below, where the thermal conductivity of the material forming the thermal insulation portion101is denoted as λ [W/m K], the cross-sectional area thereof is denoted as S [m2], the thickness thereof is denoted as L [m], and the amount of heat transfer of the excitation-side core105is denoted as w [W].
ΔT=L/S×w/λ(1)

When the thermal insulation portion101is made of permalloy, the temperature difference between the excitation-side core105and the acting-side core104is 18 K when the amount of heat transfer of the excitation-side core105is 50 W, the cross-sectional area of the thermal insulation portion101is 0.0004 m2, the thickness thereof is 0.005 m, and the thermal conductivity of permalloy is 14 W/m K. When the overall core232is formed of stacked silicon steel plates, the length of the core232is required to be twice for obtaining the same effect. Therefore, with application of the present embodiment, it is possible to realize a reduction in the size of the core unit230of the linear motor and therefore the transport apparatus100.

Note that, in the present embodiment, heat conduction from the excitation-side core105to the acting-side core104is suppressed by changing the thermal conductivity λ and the thickness L of the thermal insulation portion101with the cross-sectional area of the core232being maintained even. However, the cross-sectional area of the core232is not necessarily required to be even, and heat conduction from the excitation-side core105to the acting-side core104may be further reduced by selectively reducing the cross-sectional area in the thermal insulation portion101.

The magnetic resistance R [A/wb] occurring due to the thermal insulation portion101is expressed as Equation (2) below, where the cross-sectional area of the thermal insulation portion101is denoted as S [m2], the thickness thereof is L [m], and the relative magnetic permeability thereof is μ.
R=1/μ×L/S(2)

When the thermal insulation portion101is formed of permalloy, since the relative magnetic permeability of the thermal insulation portion101is 14 times, the magnetic resistance R of the thermal insulation portion101is 1/14, and thus an increase in the magnetic resistance R can be suppressed. However, since the saturation magnetic flux density of permalloy is smaller than that of stacked silicon steel plates forming the acting-side core104and the excitation-side core105, the motor is driven in a range of a magnetic flux that is smaller than the saturation magnetic flux density of permalloy.

Note that, although the T-shape structure in which two pairs of a coil and a magnet face each other has been illustrated as a linear motor in the present embodiment, the present embodiment is also applicable to the I-shape structure in which a pair of a coil and a magnet in which a thermal insulation structure can be arranged in the core part is employed.

As described above, according to the present embodiment, it is possible to reduce transfer of heat generated by the coil106to the acting-side core104via the excitation-side core105. Accordingly, it is possible to suppress influence of heat generated by the coil106without increasing the size of the core unit230and realize a transport apparatus that can achieve accurate positioning repeatability even with a compact apparatus as a whole.

Second Embodiment

The transport apparatus according to a second embodiment of the present invention will be described with reference toFIG.2AandFIG.2B. The same components as those in the transport apparatus according to the first embodiment are labeled with the same references, and the description thereof will be omitted or simplified.FIG.2AandFIG.2Bare sectional views illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.2Ais a sectional view in a plane parallel to the Y-Z plane including a line B-B′ of theFIG.2B. Further,FIG.2Bis a sectional view in a plane parallel to the X-Z plane including a line A-A′ of theFIG.2A.

As illustrated inFIG.2AandFIG.2B, the transport apparatus100according to the present embodiment is the same as the transport apparatus according to the first embodiment except for a difference in the configuration of each core232of the core unit230of the linear motor. That is, in the transport apparatus100according to the present embodiment, the core232of the core unit230is formed of the acting-side cores104, the excitation-side core105, and narrow portions115arranged therebetween. In the same manner as the thermal insulation portion101of the first embodiment, the narrow portion115functions as a heat conduction reduction portion that reduces heat conduction from the excitation-side core105to the acting-side core104more than in a case where the excitation-side core105and the acting-side core104are in direct contact with each other.

Although the narrow portion115is formed of the same material as that of the acting-side core104and the excitation-side core105, the cross-sectional area of the cross section in a direction perpendicular to a magnetic flux passing inside the core232is smaller than that of the acting-side core104. The minimum value of the cross-sectional area of the narrow portion115can be defined as a cross-sectional area by which a magnetic flux generated by the coil106is not saturated, for example. Although it is desirable that the narrow portions115be structured integrally with the acting-side cores104and the excitation-side core105, the narrow portions115may be formed by coupling component members that are different from the acting-side cores104and the excitation-side core105.

The temperature difference ΔT between the acting-side core104and the excitation-side core105can be increased by reducing the cross-sectional area S of the narrow portion115as illustrated in Equation (1). For example, it is assumed that the amount of heat transfer w of the excitation-side core105is 50 W, the thermal conductivity of a silicon steel plate is 30 W/m K, and the thickness of the narrow portion115is 0.005 m. In this case, if the cross-sectional area S of the narrow portion115is 0.0004 m2 that is the same as the cross-sectional area of the acting-side core104, for example, the temperature difference ΔT between the excitation-side core105and the acting-side core104will be 20 K. On the other hand, if the cross-sectional area S of the narrow portion115is reduced to 0.0003 m2, the temperature difference ΔT between the excitation-side core105and the acting-side core104can be increased to 27 K. That is, by providing the narrow portions115, it is possible to reduce heat conduction between the acting-side core104and the excitation-side core105.

As described above, according to the present embodiment, it is possible to reduce transfer of heat generated by the coil106to the acting-side core104via the excitation-side core105. Accordingly, it is possible to suppress influence of heat generated by the coil106without increasing the size of the core unit230and realize a transport apparatus that can achieve accurate positioning repeatability even with a compact apparatus as a whole.

Third Embodiment

The transport apparatus according to a third embodiment of the present invention will be described with reference toFIG.3AandFIG.3B. The same components as those in the transport apparatus according to the first and second embodiments are labeled with the same references, and the description thereof will be omitted or simplified.FIG.3AandFIG.3Bare sectional views illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.3Ais a sectional view in a plane parallel to the Y-Z plane including a line B-B′ of theFIG.3B. Further,FIG.3Bis a sectional view in a plane parallel to the X-Z plane including a line A-A′ of theFIG.3A.

As illustrated inFIG.3AandFIG.3B, the transport apparatus100according to the present embodiment is the same as the transport apparatus according to the first and second embodiments except for a difference in the configuration of each core232of the core unit230of the linear motor. That is, in the transport apparatus100according to the present embodiment, the core232of the core unit230is formed of the acting-side cores104and the excitation-side core105, and airgaps118are provided therebetween. That is, the airgap118is provided in the middle of a magnetic path. The cross-sectional area of the end of the acting-side core104(an acting-side core end116) and the cross-sectional area of the end of the excitation-side core105(an excitation-side core end117) facing each other and interposing the airgap118are larger than the cross-sectional area of other portions in order to suppress leakage of the magnetic flux in the airgap118. In the example ofFIG.3AandFIG.3B, to enhance a thermal insulation effect between the acting-side cores104and the excitation-side core105, the airgaps118are provided at both ends of the excitation-side core105.

Since the airgap118includes an air layer arranged between the acting-side core104and the excitation-side core105, the thermal conductivity is around 1/1000 times that of the thermal insulation portion101of the first embodiment or the narrow portion115of the second embodiment. Therefore, as is apparent from Equation (1), heat conduction between the acting-side core104and the excitation-side core105can be reduced more than in the case of the first and second embodiments. That is, in the same manner as the thermal insulation portion101of the first embodiment or the narrow portion115of the second embodiment, the airgap118functions as a heat conduction reduction portion that reduces heat conduction from the excitation-side core105to the acting-side core104more than in a case where the excitation-side core105and the acting-side core104are in direct contact with each other.

The magnetic resistance of the core gap G through which the permanent magnet113passes is 25 A/wb when the length of the core gap G is 0.01 m, the cross-sectional area thereof is 0.0004 m2, and the relative magnetic permeability thereof is 1. On the other hand, the magnetic resistance R of the airgap118is 0.25 A/wb when the length of the airgap118is 0.001 m, the cross-sectional area thereof is 0.004 m2, and the relative magnetic permeability thereof is 1. That is, the magnetic resistance of the airgap118is around 1/100 of the magnetic resistance of the core gap G. Therefore, the magnetic resistance of the entire core due to the airgap118being provided is increased by around 1%, which does not much affect the motor drive. It is preferable that the length of the airgap be greater than or equal to 1/20 and less than or equal to 1/3 of the length of the core gap.

Further, to obtain the advantageous effect of suppressing an increase in the magnetic resistance, the material described in the first embodiment having a larger magnetic permeability than the core material can be applied as the material of the acting-side core end116and the excitation-side core end117.

As described above, according to the present embodiment, it is possible to reduce transfer of heat generated by the coil106to the acting-side core104via the excitation-side core105. Accordingly, it is possible to suppress influence of heat generated by the coil106without increasing the size of the core unit230and realize a transport apparatus that can achieve accurate positioning repeatability even with a compact apparatus as a whole.

Fourth Embodiment

The transport apparatus according to a fourth embodiment of the present invention will be described with reference toFIG.4toFIG.5B. The same components as those in the transport apparatus according to the first to third embodiments are labeled with the same references, and the description thereof will be omitted or simplified.FIG.4is a top view illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.5AandFIG.5Bare sectional views illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.5Ais a sectional view in a plane parallel to the Y-Z plane including a line B-B′ of theFIG.4. Further,FIG.5Bis a sectional view in a plane parallel to the X-Z plane including a line C-C′ of theFIG.4.

In the present embodiment, a configuration example to which the linear motor of the third embodiment is applied to a circulation type transport apparatus will be described. The circulation type transport apparatus is a transport apparatus on which a movable mechanism having shifter structure that reciprocates a movable track unit in a plane direction so as to be able to move back and forth between a forward track and a reverse track, elevator structure that reciprocates a movable track unit vertically, or the like is mounted.

The transport apparatus100according to the present embodiment has transport modules210A and210B, a shifter unit240, and the carriage220, as illustrated inFIG.4toFIG.5B.

The transport modules210A and210B are the same as the transport module210illustrated in the third embodiment. The transport module210A forms a stationary track unit for a forward path, for example. The transport module210B forms a stationary track unit for a reverse path, for example. The transport module210A and the transport module210B are arranged such that the track units thereof are parallel to each other in the X-axis direction.

The shifter unit240has a transport module250, a guide rail126, guide blocks127. The transport module250is fixed to the guide blocks127, which is connected to and movable along the guide rail126, and is configured to move along the guide rail126using a motive power source such as an actuator under the control of the upper-level controller (not illustrated). In this sense, the transport module250forms a movable track unit.

The shifter unit240is adjacent to the transport modules210A and210B and causes the transport module250to move between a position A, which forms a track unit that continues to the transport module210A, and a position A′, which forms a track unit that continues to the transport module210B. For example, when the transport module250is located at the position A ofFIG.4, the transport module250and the transport module210A form a continuous track unit. Further, when the transport module250is located at the position A′ ofFIG.4, the transport module250and the transport module210B form a continuous track unit.

Note that, althoughFIG.4illustrates the shifter unit240configured such that the transport module250moves in parallel to the Y-axis direction, the configuration of the shifter unit240is not limited thereto. For example, a shifter unit having elevator structure in which the guide rail126is arranged along the Z-axis direction and the transport module250moves in the vertical direction may be employed. Alternatively, a shifter unit having turning structure that turns the transport module by using a rotational mechanism may be employed.

The carriage220is the same as the carriage220illustrated in the first embodiment. Although illustration is omitted inFIG.1AtoFIG.3B, the carriage220further has a scale119provided on the top plate111in addition to the top plate111, the magnet support112, the permanent magnets113, and the linear guide blocks114, as illustrated inFIG.4toFIG.5B, for example. Position information is recorded on the scale119along the moving direction of the carriage. Encoders108provided to the transport modules210A,210B, and250read the scale119of the carriage220, and thereby it is possible to acquire position information on the carriage220. A plurality of encoders108are attached to the transport modules210A,210B, and250at shorter intervals than the scale length of the scale119, so that the scale119can be read by any one of the encoders108. Note that, for better understanding of the relationship between the transport modules210A and250,FIG.4illustrates these transport modules with a part of the top plate111being cut out. The actual plane shape of the top plate111is a rectangular shape as illustrated in the dashed line inFIG.4, for example.

The carriage220is configured so as to be movable on the transport modules210A,210B, and250. This enables the carriage220, which has moved on the transport module210A, to move to the transport module210B via the transport module250of the shifter unit240, for example.

The transport module250of the shifter unit240includes shifter stands110, the linear stands102, the linear guide rails103, and the acting-side cores104as illustrated inFIG.4toFIG.5B. The length in the X-axis direction of the transport module250is a necessary and sufficient length with respect to the length in the X-axis direction of the carriage220.

The excitation-side core105, which is coupled to the acting-side cores104of the transport module250to form the core232, and the coil106provided to the excitation-side core105are arranged on an extended line of each track unit of the transport modules210A and210B in a region in which the shifter unit240is arranged. That is, the excitation-side core105and the coil106of the shifter unit240are fixed to the shifter unit240independently of the transport module250. Thereby, when the transport module250is located at the position A, the excitation-side core105on the extended line of the transport module210A and the acting-side cores104of the transport module250are magnetically coupled to each other. In such a way, a stator of the linear motor that is continuous from the transport module210A to the transport module250is formed. Further, when the transport module250is located at the position A′, the excitation-side core105on the extended line of the transport module210B and the acting-side cores104of the transport module250are magnetically coupled to each other. In such a way, a stator of the linear motor that is continuous from the transport module250to the transport module210B is formed.

The encoder108of the shifter unit240is fixed to a portion other than the transport module250by a fixing scheme so as not to physically interfere when the transport module250moves in the Y-axis direction and is configured not to move in synchronization with the transport module250. Further, a position detection device109used for detecting a position in the Y-axis direction of the transport module250is provided to the shifter unit240.

As described above, in the transport module of the present embodiment, the excitation-side core105and the coil106of the shifter unit240are fixed to the apparatus independently of the transport module250. Further, the encoder108and the position detection device109of the shifter unit240are fixed to a portion other than the transport module250. Therefore, this enables a configuration that requires no cableveyor (registered trademark) for connection cables to the peripheral device and the driver of the shifter unit240.

Therefore, in the transport apparatus of the present embodiment, no swinging of a connection cable due to motion of the movable track unit occurs, and it is possible to prevent occurrence of generation of dust or disconnection of a connection cable due to sliding or bending of the connection cable. Such a feature of the transport apparatus of the present embodiment is extremely useful in a manufacturing line of precision instruments in which it is important to suppress generation of dust, for example.

A shorter gap in a portion where the acting-side core104and the excitation-side core105face each other results in a smaller magnetic resistance Rba, which is a preferable form having a small reduction in efficiency of a motor. The magnetic resistance Rba is expressed by Equation (3) below, where the cross-sectional area of the facing surfaces of the acting-side core104and the excitation-side core105is denoted as S, the relative distance between the facing surfaces is denoted as L, and the relative magnetic permeability of air is denoted as μ.
ba=1/μ×L/S(3)

The gap (relative distance L) between the acting-side core104and the excitation-side core105is suitably adjusted so that the acting-side core104and the excitation-side core105are not in physical contact when the transport module250moves and may be set to 0.4 mm, for example. The magnetic resistance Rba in such a case is 0.001 A/wb.

The magnetic resistance Rba between the acting-side core104and the excitation-side core105is not particularly limited as long as it is a magnetic resistance by which a magnetic flux that can drive the carriage220on the transport module250can be supplied to the acting-side core104. It is desirable to set the magnetic resistance Rba as appropriate in accordance with the weight or acceleration of the carriage220, the sliding resistance, the cogging resistance, or the magnetic force or the number of poles of the permanent magnet113provided to the carriage220, or the like.

AlthoughFIG.4toFIG.5Billustrate only the single carriage220, a plurality of carriages220are arranged on the track and controlled in the actual transport apparatus.

As described above, the present embodiment includes the shifter unit240, and it is possible to suppress heat generated by the coil106from being transferred to the acting-side cores104via the excitation-side core105. Accordingly, it is possible to suppress influence of heat generated by the coil106without increasing the size of the core unit230and realize a transport apparatus that can achieve accurate positioning repeatability even with a compact apparatus as a whole.

Further, according to the present embodiment, the peripheral device of the shifter unit240can be formed of a configuration that requires no cableveyor (registered trademark), and a circulation type linear transport apparatus without generation of dust from a cableveyor (registered trademark) can be realized.

Further, with a use of the configuration of the present embodiment, the acting-side cores104and the excitation-side cores105can be separated and arranged in different rooms. For example, with a configuration in which the acting-side cores104are arranged inside a vacuum chamber and the excitation-side cores105are arranged outside the vacuum chamber, it is possible to prevent an emission gas from the coils106from being introduced in the vacuum chamber.

Fifth Embodiment

The transport apparatus according to a fifth embodiment of the present invention will be described with reference toFIG.6AandFIG.6B. The same components as those in the transport apparatus according to the first to fourth embodiments are labeled with the same references, and the description thereof will be omitted or simplified.FIG.6AandFIG.6Bare sectional views illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.6Acorresponds to a sectional view in a plane parallel to the Y-Z plane including the line B-B′ of theFIG.4. Further,FIG.6Bcorresponds to a sectional view in a plane parallel to the X-Z plane including the line C-C′ of theFIG.4.

In the configuration described in the fourth embodiment, the relative distance L between the facing surfaces of the acting-side core104and the excitation-side core105is set such that the acting-side core104and the excitation-side core105are not in physical contact with each other when the transport module250moves. However, the efficiency as a linear motor is more preferable when the relative distance L between the acting-side core104and the excitation-side core105, that is, the magnetic resistance Rba is smaller, and a state where the relative distance L is 0 mm is ideal.

In terms of the above, in the transport apparatus according to the present embodiment, the shifter unit240further has a movable mechanism that causes the excitation-side core105and the coil106(the portion surrounded by a dashed line inFIG.6AandFIG.6B) to move vertically, in addition to the configuration of the fourth embodiment. This movable mechanism has a mechanism that lifts and lowers the excitation-side core105and the coil106such that the relative distance L between the excitation-side core105and the acting-side core104can be freely changed when the transport module250is located at a predetermined position where the carriage220is ready to move to the stationary track unit. The elevating control of the excitation-side core105and the coil106can be performed by the upper-level controller (not illustrated) by using an electric actuator (not illustrated), for example.

In response to detecting from the position detection device109that the transport module250is located at the position A ofFIG.4, the upper-level controller drives the movable mechanism at any timing before starting motion of the carriage220from the transport module210A to the transport module250. The movable mechanism lifts the excitation-side core105and the coil106arranged at the position A by using the electric actuator and reduces the relative distance between the facing surfaces of the acting-side core104and the excitation-side core105. For example, the movable mechanism causes the facing surfaces of the acting-side core104and the excitation-side core105to come into contact with each other and thereby sets the relative distance L to 0 mm.

Next, in response to the encoder108detecting that the motion of the carriage220to the transport module250is completed, the movable mechanism lowers the excitation-side core105and causes the transport module250to be ready to move under the control of the upper-level controller.

In response to detecting from the position detection device109that the transport module250has moved to the position A′ ofFIG.4, the upper-level controller drives the movable mechanism. The movable mechanism lifts the excitation-side core105and the coil106arranged at the position A by using the electric actuator. Thereby, the driver unit (not illustrated) is ready to drive the carriage220located on the transport module250.

The elevation distance of the excitation-side core105may be any distance as long as a gap by which the acting-side core104and the excitation-side core105are not in physical contact with each other can be maintained when the transport module250is moving and, specifically, order of around several millimeters is sufficient. Therefore, no cableveyor (registered trademark) for connection cables to the excitation-side core105and the driver (not illustrated) is required.

Note that, although the movable mechanism is driven so that the acting-side core104and the excitation-side core105come into contact with each other in the present embodiment, it is not necessarily required to cause the acting-side core104and the excitation-side core105to come into contact with each other. When the relative distance L between the acting-side core104and the excitation-side core105is set to some distance larger than 0 mm, heat conduction between the acting-side core104and the excitation-side core105can be effectively reduced as described in the third embodiment. Even when the acting-side cores104and the excitation-side core105are contacted to each other, since these cores are not integrally formed, the advantageous effect of preventing heat conduction can be expected to some degrees.

As described above, according to the present embodiment, a configuration that requires no cableveyor (registered trademark) for connection cables to the coil106and the driver of the movable track unit can be provided, and a circulation type linear transport apparatus without generation of dust from a cableveyor (registered trademark) can be realized.

Sixth Embodiment

The transport apparatus according to a sixth embodiment of the present invention will be described with reference toFIG.7toFIG.8B. The same components as those in the transport apparatus according to the first to fifth embodiments are labeled with the same references, and the description thereof will be omitted or simplified.FIG.7is a top view illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.8AandFIG.8Bare sectional views illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.8Ais a sectional view in a plane parallel to the Y-Z plane including a line B-B′ of theFIG.7. Further,FIG.8Bis a sectional view in a plane parallel to the X-Z plane including a line C-C′ of theFIG.7.

The length of the linear guide rail103provided to the transport module250of the shifter unit240is determined so as to be a necessary and sufficient length for the length in the X-axis direction of the carriage220as described above. In the fourth embodiment, as illustrated inFIG.4, the same number of sets of the excitation-side cores105and the coils106as the number of pairs of the acting-side cores104provided to correspond to the length of the linear guide rail103of the transport module250are arranged to the shifter unit240.

Herein, in the transport module250in the transport apparatus of the fourth embodiment, both the end on a side that the carriage220enters from the transport module210A and the end on a side that the carriage220exits to the transport module210B are on the right side in the drawings. Therefore, on the left side of the transport module250that is opposite to the right side that the carriage220enters and exits, the acting-side cores104, the excitation-side cores105, and the coils106used for driving the carriage220are not necessarily required.

Accordingly, in the transport apparatus of the present embodiment, only the minimal number of excitation-side cores105and coils106required for driving to perform entry and exit of the carriage220are arranged in the shifter unit240to achieve a reduction of cost. The acting-side cores104are arranged such that the number of acting-side cores104corresponds to the length of the linear guide rail103of the transport module250so that cogging of the movable element is not increased.

As described above, according to the present embodiment, a configuration that requires no cableveyor (registered trademark) for connection cables to the coil106and the driver of the movable track unit can be provided, and a circulation type linear transport apparatus without generation of dust from a cableveyor (registered trademark) can be realized. Further, the number of excitation-side cores105and coils106can be reduced to achieve a reduction of cost.

Seventh Embodiment

The transport apparatus according to a seventh embodiment of the present invention will be described with reference toFIG.9andFIG.10. The same components as those in the transport apparatus according to the first to sixth embodiments are labeled with the same references, and the description thereof will be omitted or simplified.FIG.9is a top view illustrating a general configuration of the transport apparatus according to the present embodiment.FIG.10is a schematic diagram illustrating the structure of cores of the transport module in the transport apparatus according to the present embodiment.

As described in the sixth embodiment, in the transport apparatus of the fourth embodiment, the acting-side core104, the excitation-side core105, and the coil106used for driving the carriage220are not necessarily required on the left side of the transport module250that is opposite to the right side that the carriage220enters and exits. Further, with a configuration in which the cores of the stator of the transport module250are magnetically coupled to the cores of the stator of the transport module210A or210B, the coil106is not necessarily required to be arranged on the right side of the transport module250that the carriage220enters and exits.

In the present embodiment, a transport apparatus having a simpler configuration in terms of the above will be described. With application of the present embodiment, it is possible to realize the same advantageous effects as those in the fourth embodiment and achieve a further reduction of cost.

As illustrated inFIG.9, the transport modules210A and210B forming the stationary track units have cores107. The core107has a shape in which cores of a plurality of coils106forming the U-phase, the V-phase, and the W-phase are integrally formed. Specifically, for example, 12 coils106aligned in the moving direction (X-axis direction) of the movable element are provided to a single core107, a plurality of these cores107are aligned, and thereby the stator of the linear motor is formed.

The transport module250forming the movable track unit has acting-side cores125and cores123. The coil106is not provided to the acting-side core125, the acting-side core125and the core107are magnetically coupled to each other, and thereby the coil106of the transport module210A or the transport module210B also serves as the coil of the transport module250.

FIG.10illustrates in more detail a portion in which the acting-side core125of the transport module250and the core107of the transport module210A are coupled to each other. The gap between the facing surfaces of the core107and the acting-side core125is set to a distance by which the transport module250forming the movable track unit and the transport module210A forming the stationary track unit do not physically interfere with each other. It is desirable that this gap be narrow as much as possible in terms of reducing the magnetic resistance between the core107and the acting-side core125. For example, the cross-sectional area of the facing surfaces of the core107and the acting-side core125can be set to 400 mm2 per core on one side, and the gap described above can be set to 0.2 mm Note that, although permanent magnets120,121, and122are of the three-pole configuration inFIG.10, the configuration is not limited thereto.

When the acting-side core125of the transport module250and the core107of the transport module210A are in the positional relationship as illustrated inFIG.10, the acting-side core125and the core107are magnetically coupled to each other. Further, the acting-side core125is subjected to a magnetic flux excited by the coil106provided to the core107of the transport module210A and forms a magnetic circuit illustrated by arrows inFIG.10. The carriage220located on the transport module250is subjected to a magnetic flux excited by the coil106via the core107and the acting-side core125and thereby is ready to move in the X-axis direction.

The core123of the transport module250is provided for reducing cogging of the movable element. That is, the core123functions as a cogging reduction core. The core123is arranged such that a magnetic flux excited by the coil106is transferred to the permanent magnet120via the acting-side core125. Specifically, the core123is arranged such that magnetic resistances Rcc and Rcm satisfy the relationship of Rcc>Rcm, where the magnetic resistance occurring due to the distance between the acting-side core125and the core123is denoted as Rcc, and the magnetic resistance occurring due to the distance between the acting-side core125and the permanent magnet120is denoted as Rcm. When these magnetic resistances satisfy the relationship of Rcc>Rcm, a magnetic circuit formed via the permanent magnet120by the magnetic flux occurring due to the coil106is dominant, and the carriage220located on the transport module250can be driven.

In the configuration in which the acting-side core125of the transport module250is separated from the core107, the advantageous effect of reducing transfer of heat generated by the coil106to the acting-side core125can also be expected in the same manner as described in the above embodiments.

As described above, according to the present embodiment, a configuration that requires no connection cable to the coil and the driver for the movable track unit can be provided, and a circulation type linear transport apparatus without generation of dust can be realized by using a configuration that requires no cableveyor (registered trademark). Further, the number of excitation-side cores105and coils106can be reduced to achieve a reduction of cost.

Eighth Embodiment

The transport apparatus according to an eighth embodiment of the present invention will be described with reference toFIG.11AtoFIG.11C. The same components as those in the transport apparatus according to the first to seventh embodiments are labeled with the same references, and the description thereof will be omitted or simplified.FIG.11AtoFIG.11Care schematic diagrams illustrating the structure and operation of cores of a transport module in the transport apparatus according to the present embodiment.

The transport apparatus according to the present embodiment is the same as the transport apparatus of the seventh embodiment except for further having cores124at the end of on the transport module250side of the transport modules210A and210B forming the stationary track unit, as illustrated inFIG.11A. The core124is configured to be movable in the moving direction of the movable element, and the gap between the core124and the core107and the gap between the core124and the acting-side core125can be freely adjusted. The core124is configured to be able to be magnetically coupled to the core107and the acting-side core125.

When the movable element is driven by the magnetic circuit formed of the acting-side core125and the core124, the core124is arranged at a position where the magnetic resistance between the core107and the core124is larger than the magnetic resistance between the acting-side core125and the core124(FIG.11B). On the other hand, when the movable element is driven by the magnetic circuit formed of the core107and the core124, the core124is arranged at a position where the magnetic resistance between the acting-side core125and the core124is larger than the magnetic resistance between the core107and the core124(FIG.11C). Note that a smaller magnetic resistance in a gap on the driving side of the movable element is preferable. In terms of the above, a state where the cores of interest are in contact with each other is desirable.

The mechanism for moving the core124can be implemented by using an electric actuator (not illustrated) and controlling the electric actuator from the upper-level controller (not illustrated).

Although the core123described in the seventh embodiment is not illustrated inFIG.11AtoFIG.11C, the transport module250may further have the core123. When the transport module250has the core123, the core123is arranged such that a magnetic flux excited by the coil106is transferred to the permanent magnet120via the acting-side core125. Specifically, the core123is arranged such that magnetic resistances Rcc and Rcm satisfy the relationship of Rcc>Rcm, where the magnetic resistance occurring due to the distance between the acting-side core125and the core123is denoted as Rcc, and the magnetic resistance occurring due to the distance between the acting-side core125and the permanent magnet120is denoted as Rcm.

As described above, according to the present embodiment, a configuration that requires no connection cable to the coil and the driver for the movable track unit can be provided, and a circulation type linear transport apparatus without generation of dust from a cableveyor (registered trademark) can be realized. Further, the number of excitation-side cores105and coils106can be reduced to achieve a reduction of cost.

Ninth Embodiment

The transport apparatus according to a ninth embodiment of the present invention will be described with reference toFIG.12AandFIG.12B. The same components as those in the transport apparatus according to the first to eighth embodiments are labeled with the same references, and the description thereof will be omitted or simplified.

FIG.12AandFIG.12Bare schematic diagrams illustrating the overall configuration of the transport apparatus including a movable element1101and a stator1201according to the present embodiment. Note thatFIG.12AandFIG.12Beach illustrate an extracted primary portion of the movable element1101and the stator1201. Further,FIG.12Ais a diagram of the movable element1101when viewed from the Y direction described later, andFIG.12Bis a diagram of the movable element1101when viewed from the Z direction described later.

As illustrated inFIG.12AandFIG.12B, the transport apparatus according to the present embodiment has the movable element1101forming a carriage or a slider and the stator1201forming a transport path. The transport apparatus is provided with a movable magnet type linear motor (a moving permanent magnet type linear motor, a movable field system type linear motor). Furthermore, the transport apparatus in the present embodiment does not have any guide device such as a linear guide and is configured as a magnetic floating type transport apparatus that transports the movable element1101in a contactless manner on the stator1201.

The transport apparatus transports a workpiece1301provided on the movable element1101to a process apparatus that performs a processing operation on the workpiece1301by transporting the movable element1101by using the stator1201, for example. Although the form in which the workpiece1301is mounted on the movable element1101is illustrated in the present embodiment, a form is not limited thereto, and a form in which the workpiece1301is held on the under surface of the movable element1101and transported may be employed, for example. Further, a form in which the workpiece1301is held on the side face of the movable element1101and transported may be employed. By performing a processing operation on the workpiece1301, it is possible to manufacture a precision article. Note that, although one movable element1101is illustrated for the stator1201inFIG.12AandFIG.12B, the number thereof is not limited thereto. In the transport apparatus, a plurality of movable elements1101may be transported on the stator1201.

Herein, coordinate axes, directions, and the like used in the following description are defined. First, the X-axis is defined in the horizontal direction that is a transport direction of the movable element1101, and the transport direction of the movable element1101is defined as the X direction. Further, the Z-axis is defined in the perpendicular direction that is a direction orthogonal to the X direction, and the perpendicular direction is defined as the Z direction. Further, the Y-axis is defined in a direction orthogonal to the X-direction and the Z-direction, and the direction orthogonal to the X direction and the Z direction is defined as the Y direction. Furthermore, rotation around the X-axis is denoted as Wx, and rotation around the Y-axis and rotation around the Z-axis are denoted as Wy and Wz, respectively. Further, “*” is used as a symbol of multiplication. Further, the center of the movable element1101is defined as the origin O, on the positive (+) side of Y is denoted as R-side, and on the negative (−) side of Y is denoted as L-side. Note that, while the transport direction of the movable element1101is not necessarily required to be the horizontal direction, the transport direction is defined as the X direction also in such a case, and the Y direction and the Z direction may be defined in the same manner.

Next, the movable element1101that is a transport target in the transport apparatus according to the present embodiment will be described with reference toFIG.12A,FIG.12B, andFIG.13.FIG.13is a schematic diagram illustrating the movable element1101and the stator1201in the transport apparatus according to the present embodiment. Note thatFIG.13is a diagram of the movable element1101and the stator1201when viewed from the X direction. Further, the left part ofFIG.13illustrates a cross section (A) taken along a line (A)-(A) ofFIG.12B. Further, the right part ofFIG.13illustrates a cross section (B) taken along a line (B)-(B) ofFIG.12B.

The permanent magnets1103are aligned in two lines along the L-side end and the R-side end on the upper surface parallel to the X direction of the movable element1101and are attached thereto. Specifically, the permanent magnets1103aR,1103bR,1103cR, and1103dR are attached on the R-side on the upper surface of the movable element1101. Further, the permanent magnets1103aL,1103bL,1103cL, and1103dL are attached on the L-side on the upper surface of the movable element1101. Note that, in the following, the permanent magnet of the movable element1101is simply denoted to as “permanent magnet1103” unless specific distinction thereof is required. Further, when the R-side and the L-side are not required to be distinguished but each permanent magnet1103is required to be specified individually, each permanent magnet1103is specified individually by using a reference from which R or L has been removed from the end of the reference for each permanent magnet1103and which therefore ends a small letter alphabet as an identifier. In such a case, each permanent magnet1103is individually specified by denoting “permanent magnet1103a”, “permanent magnet1103b”, “permanent magnet1103c”, or “permanent magnet1103d”.

The permanent magnets1103aR and1103dR are attached to one end and the other end in the X direction on the R-side of the upper surface parallel to the X direction of the movable element1101. The permanent magnets1103bR and1103cR are attached between the permanent magnets1103aR and1103dR on the R-side on the upper surface of the movable element1101. The permanent magnets1103aR,1103bR,1103cR, and1103dR are arranged at an equal pitch in the X direction, for example. Further, the permanent magnets1103aR,1103bR,1103cR, and1103dR are arranged such that the centers of respective permanent magnets are aligned on a straight line parallel to the X direction at a predetermined distance rx3 away from the center of the upper surface of the movable element1101to the R-side, for example.

The permanent magnets1103aL and1103dL are attached to one end and the other end in the X direction on the L-side of the upper surface parallel to the X direction of the movable element1101. The permanent magnets1103bL and1103cL are attached between the permanent magnets1103aL and1103dL on the L-side on the upper surface of the movable element1101. The permanent magnets1103aL,1103bL,1103cL, and1103dL are arranged at an equal pitch in the X direction, for example. Further, the permanent magnets1103aL,1103bL,1103cL, and1103dL are arranged such that the centers of respective permanent magnets are aligned on a straight line parallel to the X direction at a predetermined distance rx3 away from the center of the upper surface of the movable element1101to the L-side, for example. Furthermore, the permanent magnets1103aL,1103bL,1103cL, and1103dL are arranged at the same positions as the permanent magnets1103aR,1103bR,1103cR, and1103dR, respectively, in the X direction.

The permanent magnets1103aand1103dare attached at positions at a distance rz3 away from the origin O, which is the center of the movable element1101, to one side and the other side in the X direction, respectively. The permanent magnets1103a,1103b,1103c, and1103dare attached at positions at the distance rx3 in the Y direction away from the origin O, respectively. The permanent magnets1103cand1103bare attached at positions at a distance ry3 away from the origin O to one side and the other side in the X direction, respectively.

Each of the permanent magnets1103aR,1103dR,1103aL, and1103dL is a set of two permanent magnets arranged parallel to the Y direction. Each of the permanent magnets1103aand1103dis configured such that two permanent magnets are aligned parallel to the Y direction such that the polarities of the outer magnetic poles facing the stator1201side are different alternately. Note that the number of permanent magnets arranged parallel to the Y direction forming the permanent magnets1103aand1103dis not limited to two and may be any number as long as it is plural. Further, the direction in which the permanent magnets forming the permanent magnets1103aand1103dare arranged is not necessarily required to be the Y direction orthogonal to the X direction, which is the transport direction, and may be any direction that crosses the X direction. That is, the permanent magnets1103aand1103dmay be any magnet group made of a plurality of permanent magnets arranged parallel to a direction crossing the X direction such that the polarities of respective magnetic poles alternate.

On the other hand, each of the permanent magnets1103bR,1103cR,1103bL, and1103cL is a set of three permanent magnets arranged parallel to the X direction. Each of the permanent magnets1103band1103cis configured such that three permanent magnets are aligned parallel to the X direction such that the polarities of the outer magnetic poles facing the stator1201side are different alternately. Note that the number of permanent magnets arranged parallel to the X direction forming the permanent magnets1103band1103cis not limited to three and may be any number as long as it is plural. That is, the permanent magnets1103band1103cmay be any magnet group made of a plurality of permanent magnets arranged parallel to the X direction such that the polarities of respective magnetic poles alternate.

Each permanent magnet1103is attached to each of yokes1107provided on the R-side and the L-side on the upper surface of the movable element1101. The yoke1107is formed of a substance having a large magnetic permeability, for example, iron.

In such a way, the center axis parallel to the X-axis of the movable element1101is defined as a symmetry axis, and the plurality of permanent magnets1103are arranged to the movable element1101symmetrically on the R-side and the L-side on the upper surface. The movable element1101on which the permanent magnets1103are arranged is configured to be movable while the attitude thereof is controlled in six axes by electromagnetic force applied to the permanent magnet1103from a plurality of coils1106of the stator1201as described later.

The movable element1101is movable in the X direction along the plurality of coils1106arranged in two lines parallel to the X direction. The movable element1101is transported in a state where the workpiece1301to be transported is placed or mounted on the upper surface or the under surface thereof. The movable element1101may have a holding mechanism that holds the workpiece1301on the movable element1101, such as a workpiece holder, for example.

Next, the stator1201in the transport apparatus according to the present embodiment will be described with reference toFIG.12AandFIG.13.

A plurality of core units1230are aligned at a predetermined interval along the moving direction (X-axis direction) of the movable element1101and form a stator of the linear motor. Each of the plurality of core units1230has a core1232and a coil1106. The core1232has excitation-side cores1105, acting-side cores1104, and thermal insulation portions1102each provided between the acting-side core1104and the excitation-side core1105. That is, the thermal insulation portion is provided in the middle of a magnetic path. Note that, althoughFIG.12Aillustrates the transport apparatus having nine core units1230aligned in the X-axis direction for simplified illustration of the drawing, the transport apparatus has a necessary number of core units1230for forming a linear motor of any length in the actual implementation. The present embodiment illustrates an example in which the thermal insulation portion1102is a partition wall that partitions stations forming a production apparatus, such as a partition wall of a vacuum (decompression) chamber or a partition wall of a chamber used for separating a gas, which is different from air, from the air or the like. However, without being limited to the above, the thermal insulation portion1102may be a coil box covering a plurality of core units, for example.

The acting-side core1104is connected and fixed to the thermal insulation portion1102(the partition wall of a chamber in the present embodiment) in the present embodiment. Without being limited to the above, however, the acting-side core1104may be connected and fixed to a coil box covering a plurality of core units, or the coil box partially having high magnetic permeability, for example. The excitation-side core1105is connected to the acting-side core1104via the thermal insulation portion1102(the partition wall of a chamber in the present embodiment). The material of the acting-side core1104and the excitation-side core1105is not particularly limited, and a magnetic material such as stacked silicon steel plates may be applied thereto, for example.

Each coil1106is wound around the excitation-side core1105of the core1232and has a role of exciting the core1232. The acting-side cores1104are arranged so as to be magnetically coupled to the excitation-side core1105, are subjected to a magnetic flux generated by the excitation-side core1105, and cause this magnetic flux to work on the movable element1101arranged in the core gap G. The thermal insulation portion1102functions as a heat conduction reduction portion that reduces heat conduction from the excitation-side core1105to the acting-side core1104more than in a case where the excitation-side core1105and the acting-side core1104are in direct contact with each other.

Further, for example, a structure such as a gate valve may be present between the core units1230. In such a place, the core units1230may be unable to be arranged continuously. In such a place, when the movable element passes through the boundary thereof, a discontinuous point may occur in driving power corresponding to floating, position control, or driving force obtained from a drive system on the stator side, and there is a risk of problems of deviation of the movable element from a target track, occurrence of displacement, or reduction in position accuracy. In such a place, it is preferable to employ arrangement in which the length of the acting-side core in a direction toward a place where a core unit is unable to be arranged is longer than the typical length of the acting-side core as with the acting-side core1104aofFIG.12A. Since this can increase attractive force, reduction in position accuracy can be suppressed.

Modified Embodiments

The present invention is not limited to the embodiments described above, and various modifications are possible. For example, an example in which a part of the configuration of any of the embodiments is added to another embodiment or an example in which a part of the configuration of any of the embodiments is replaced with a part of the configuration of another embodiment is also one of the embodiments of the present invention.

Note that all the embodiments described above merely illustrate embodied examples in implementing the present invention, and the technical scope of the present invention is not to be construed in a limiting sense by these embodiments. That is, the present invention can be implemented in various forms without departing from the technical concept or the primary feature thereof. To publicize the scope of the present invention, the following claims are appended.

According to the present invention, it is possible to realize a compact linear motor and a compact transport apparatus that suppress influence due to heat generated from coils and have accurate positioning performance, accurate positioning repeatability, and accurate transport performance. Further, it is possible to suppress generation of dust or disconnection of a cable due to sliding or the like of a connection cable and realize a transport apparatus suitable for application to a manufacturing line for precision instruments.