Patent ID: 12211645

DETAILED DESCRIPTION

Some embodiments of the present invention will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described or shown in the drawings as the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.

FIG.1is a cross-sectional view schematically showing the configuration of a solenoid actuator according to an embodiment.

FIG.1omits illustration of a resin mold of the solenoid actuator. Further, a magnetic path4is shown only for one side of a coil3(a left-hand area in the figure), but the same magnetic path4is formed on either side (a right-hand area in the figure) of the annularly disposed coil3as well.

In some embodiments, as shown inFIG.1, the solenoid actuator1includes the coil3, a stator10,20for forming the magnetic path4around the coil3, and the mover50axially movable by a magnetic force generated by the coil3.

The coil3is formed by winding a wire composed of a conductor such as copper or copper alloy around a central axis O of the solenoid actuator1. The coil3has a substantially annular shape centering on the central axis O as a whole. The coil3is electrically connected to a terminal (not shown), and power is supplied to the coil3via the terminal. When the coil3is energized, a magnetic force for attracting the mover50is generated.

The coil3may be housed in a bobbin (not shown).

The stator10,20includes the first stator10and the second stator20located on both sides of the coil3in the axial direction of the solenoid actuator1. The stator10,20is composed of a magnetic material that may be, for example, iron and is disposed annularly around the central axis O so as to surround the coil3.

The first stator10and the second stator20are arranged so as to face each other across an air gap11in the axial direction, on an inner peripheral side of the coil3and an outer peripheral side of the mover50described later.

The air gap11is provided to restrict a magnetic flux flow from the first stator10directly toward the second stator20without via the mover50, and to efficiently flow a magnetic flux from the first stator10toward the second stator20via the mover50.

In the examples shown inFIG.1, the first stator10and the second stator20are in contact with each other at a contact section12located on an outer peripheral side of the coil3.

In this case, the first stator10and the second stator20may integrally be formed by the resin mold (not shown) in a state where the first stator10and the second stator20face each other via the air gap11on the inner peripheral side of the coil3and are in contact with each other at the contact section12on the outer peripheral side of the coil3.

The position of the contact section12between the first stator10and the second stator20is not particularly limited, but the contact section12may be located at a central position of the coil3in the axial direction as in the examples ofFIG.1, or the contact section12may exist at a position different from the central position of the coil3.

In another embodiment, the solenoid actuator1does not have a section where the first stator10and the second stator20contact each other.

For example, if the solenoid actuator1includes at least one another stator other than the first stator10and the second stator20, the at least one another stator may be located between the first stator10and the second stator20, and may form the magnetic path4together with the first stator10and the second stator20. The another stator is thus interposed between the first stator10and the second stator20, which may obtain the configuration where the first stator10and the second stator20do not directly contact each other.

Further, voids may exist between the plurality of stators including the first stator10and the second stator20.

In some embodiments, as shown inFIG.1, the first stator10includes a first yoke14and a cylindrical guide30fixed to an inner peripheral side of the first yoke14.

The cylindrical guide30fixed to the inner peripheral side of the first yoke14faces the second stator20across the air gap11between the first stator10and the second stator20. That is, a distal end31of the cylindrical guide30is not in contact with a distal end21of the second stator20, but is separated by the air gap11.

Herein, the air gap11means a minimum gap on the inner peripheral side of the coil3, and between the second stator20and the first stator10including the first yoke14and the cylindrical guide30.

The cylindrical guide30may be disposed such that the distal end31of the cylindrical guide30is located in a radial position range at least partially overlapping the distal end21of the second stator20.

In some embodiments, as shown inFIG.1, the cylindrical guide30is disposed such that the distal end31projects from the first yoke14toward the second stator20. That is, the cylindrical guide30axially extends toward the second stator20beyond a distal end position of the first yoke14.

By thus extending the cylindrical guide30toward the second stator20beyond the distal end position of the first yoke14, it becomes easier to secure a magnetism transfer area between the mover50and the cylindrical guide30(a magnetic tube32to be described later), and it is possible to increase a magnetic flux flowing between the second stator20and the mover50at the original position.

Further, the cylindrical guide30may axially extend to a rear end51of the mover50at the original position, or to a side opposite to the second stator20beyond the rear end51of the mover50at the original position.

In the exemplary embodiment shown inFIG.1, the cylindrical guide30axially extends beyond the rear end51of the mover50at the original position to the side opposite to the second stator20. That is, a proximal end33opposite to the distal end31of the cylindrical guide30axially projects from the rear end51of the mover50at the original position to the side opposite to the second stator20. By thus extending the cylindrical guide30beyond the rear end51of the mover50at the original position to the side opposite to the second stator20, it becomes easier to secure the magnetism transfer area between the mover50and the cylindrical guide30(the magnetic tube32to be described later). As a result, an overall magnetic resistance of the magnetic path4passing through the mover50is reduced, making it possible to increase the magnetic flux flowing between the second stator20and the mover50at the original position.

The first yoke14of the first stator10is formed of a magnetic material that may be, for example, iron and is disposed so as to surround the coil3together with the second stator20. The first yoke14may contact the second stator20at a contact section12on the outer peripheral side of the coil3.

The first yoke14has a first through hole15for receiving the cylindrical guide30. The first through hole15may be a circular hole concentric with the central axis O of the solenoid actuator1.

As shown inFIG.1, an inner wall of the first through hole15of the first yoke14includes a contact region15awhich is in contact with an outer peripheral surface of the cylindrical guide30and a non-contact region15bwhich is not in contact with the outer peripheral surface of the cylindrical guide30. The non-contact region15bis adjacent to the contact region15ain the axial direction. The non-contact region15bis located opposite to the second stator20across the contact region15ain the axial direction.

In some embodiments, an inner diameter of the first through hole15at the contact region15ais the same as that at the non-contact region15b. That is, the inner wall of the first through hole15is not provided with a step that restricts the axial position of the cylindrical guide30with respect to the first yoke14.

Thus, the step of the inner wall of the first through hole15does not hinder the axial positioning of the cylindrical guide30with respect to the second stator20. Accordingly, when assembling the cylindrical guide30to the first yoke14, it is possible to appropriately adjust the axial position of the distal end31of the cylindrical guide30and it becomes easier to control the air gap11with high accuracy.

In some embodiments, as shown inFIG.1, the second stator20includes a second yoke24and a second cylindrical member40fixed to an inner peripheral side of the second yoke24.

The second yoke24is formed of a magnetic material that may be, for example, iron and is disposed so as to surround the coil3together with the first stator10. The second yoke24may contact the first stator10at the contact section12on the outer peripheral side of the coil3.

The second yoke24has a second through hole25for receiving the second cylindrical member40. The second through hole25may be a circular hole concentric with the central axis O of the solenoid actuator1.

In the exemplary embodiment shown inFIG.3, the second cylindrical member40has the distal end21of the second stator20forming the air gap11with the first stator10.

In another embodiment, the entire second stator20is configured as one piece.

As in the embodiment shown inFIG.1, By providing the second cylindrical member40of the second stator20directly related to the air gap11separately from the second yoke24, it becomes easier to control the air gap11with higher accuracy, as compared with a case where the entire second stator20is configured as one piece.

For example, consider a case where, when assembling the cylindrical guide30to the first yoke14, the position of the distal end31of the cylindrical guide30is adjusted with reference to the reference surface22of the second stator20(that is, the axial end surface22of the second yoke24opposite to the first stator10). In this case, after adjusting the axial position of the distal end31of the cylindrical guide30with respect to the axial end surface22of the second yoke24, the second cylindrical member40may axially be aligned with respect to the axial end surface22of the second yoke24when assembling the second cylindrical member40to the second yoke24. Consequently, since only the dimension of the second cylindrical member40of the second stator20(the axial dimension of the second cylindrical member40from the reference surface22of the second yoke24to the air gap11) substantially affects the air gap11, the highly accurate air gap11can easily be formed.

In some embodiments, as shown inFIG.1, the second cylindrical member40is disposed so as to project from the second yoke24toward the first stator10.

That is, the distal end21of the second stator20formed by the second cylindrical member40is located on the first stator10side beyond the distal end of the second yoke24in the axial direction.

Some solenoid actuator, such as a linear solenoid, is desirably configured such that a change in attractive force with respect to a current has a linear characteristic. In order to achieve this linear characteristic, the distal end of the second stator, which is disposed downstream in a moving direction of the mover from the original position when the coil is energized, advantageously has a shape tapered toward the air gap.

In this regard, as described above, by axially projecting the second cylindrical member40forming the air gap11from the second yoke24, the overall shape of the second stator20formed by the second yoke24and the second cylindrical member40can be made closer to the above-described tapered shape.

In the exemplary embodiment shown inFIG.1, the second yoke24decreases in thickness t toward the air gap11. That is, the second yoke24has a tapered portion26with the thickness t decreasing toward the air gap11, in a distal end region on the air gap11side.

Herein, the thickness t of the second yoke24is the radial dimension of the second yoke24.

Since the second yoke24thus has a thickness distribution decreasing toward the air gap11, in combination with the configuration where the second cylindrical member40projects from the second yoke24toward the first stator10, the overall shape of the second stator20can be made much closer to the aforementioned tapered shape.

When the coil3is energized, a magnetic flux flows in the magnetic path4formed around the coil3by the first stator10and the second stator20each having the above configuration.

As a result, the mover50is attracted by the magnetic flux flowing through the magnetic path4and axially moves toward the second stator20from the original position radially inward of the first stator10.

The second stator20forms a cavity28, which is configured to receive the mover50axially approaching when the coil3is energized, radially inward of the second stator20.

In the embodiment shown inFIG.1, the cavity28is defined by the second cylindrical member40of the second stator20.

In some embodiments, as shown inFIG.1s, the mover50is a plunger52disposed at an end portion of a shaft54which is an output shaft of the solenoid actuator1.

The plunger52has a through hole into which the shaft54is press-fitted. The shaft54is press-fitted into the through hole of the plunger52such that the axis of the shaft54and the axis of the plunger52are aligned.

The plunger52as the mover50is formed of a magnetic material that may be, for example, iron and is mounted on an outer peripheral side of the shaft54.

The plunger52has a diameter which is larger than a diameter of the shaft54and is smaller than an inner diameter of cylindrical guide30of first stator10. Further, the diameter of the plunger52is smaller than the diameter of the cavity28formed by the second stator20.

When the coil3is in the non-excited state, the shaft54is biased by a spring (not shown) in a direction opposite to an arrow B, and the plunger52as the mover50is located radially inward of the first stator10(cylindrical guide30). At this time, it is only necessary that the plunger52is substantially be located radially inward of the cylindrical guide30, and the end portion of the plunger52may project from the first stator10(cylindrical guide30) toward the second stator20.

On the other hand, when the coil3is energized, the plunger52as the mover50intrudes in the cavity28formed radially inward of the second stator20. At this time, it is only necessary that at least a portion of the plunger52is located within the cavity28, and a remaining portion of the plunger52may project from the cavity28toward the first stator10.

The shaft54to which the plunger52having the above configuration is fixed penetrates the second stator20and extends to the outside of the solenoid actuator1. The shaft54is moved in the direction of the arrow B by the actuation of the solenoid actuator1, and transmits a driving force of the solenoid actuator1to an external device (not shown).

The external device driven by the solenoid actuator1is not particularly limited, but may be, for example, a spool for hydraulically controlling a valve timing of an intake valve or an exhaust valve of a vehicle engine.

The shaft54may slidably be supported on the second stator20side by a bearing.

In the embodiment shown inFIG.1, a radially inner portion of the second cylindrical member40forming part of the second stator20functions as a bearing portion53, and the shaft54is slidably supported by the bearing portion53of the second cylindrical member40.

FIGS.2to4are each a cross-sectional view showing a detailed structure of the solenoid actuator in a magnetic flux transfer region between the stator and the mover according to an embodiment.

FIG.2shows a non-excited state of the coil3in which the mover50exists at the original position. Herein, the original position of the mover50is represented as X=0 using a position coordinate X of an end surface of the mover50, and can be rephrased as a stroke start position where a stroke amount of the solenoid actuator1is zero.

By contrast,FIG.3shows a state in which the mover50moves by a stroke amount X1with reference to the original position, and the position coordinate X of the end surface of the mover50is the intermediate position X1. Likewise,FIG.4shows a state in which the mover50moves by a maximum stroke amount X2with reference to the original position, and the position coordinate X of the end surface of the mover50is the maximum stroke position X2(>X1).

In some embodiments, as shown inFIGS.2to4, the cylindrical guide30includes the magnetic tube32with an outer peripheral surface contacting the inner wall of the first through hole15of the first yoke14, and a non-magnetic layer34formed on an inner peripheral surface of the magnetic tube32.

The magnetic tube32is composed of a magnetic material that may be, for example, iron, and faces the second stator20across the air gap11. That is, the magnetic tube32of the magnetic portion of the first stator10including the first yoke14and the cylindrical guide30is disposed closest to the distal end21of the second stator20.

A radial position range of the magnetic tube32may at least partially overlap the radial position range of the distal end21of the second stator20that forms the air gap11with the magnetic tube32.

The non-magnetic layer34of the cylindrical guide30is disposed on the inner peripheral surface of the magnetic tube32so as to face the outer peripheral surface of the mover50.

Whereby, the cylindrical guide30can axially guide the mover50by bringing the mover50into sliding contact with the non-magnetic layer34.

The non-magnetic layer34may be composed of a low-friction material such as copper or PTFE (polytetrafluoroethylene). The non-magnetic layer34may be deposited on the inner surface of the cylindrical guide30by an application method such as sintering or impregnation, for example. In the exemplary embodiment, the non-magnetic layer34is formed by impregnating a copper alloy porous layer formed by sintering with a resin material containing PTFE.

In general, a guide (bearing) for constraining a radial position of a mover and axially guiding the mover is provided at a location separate from a radial magnetic gap between a yoke and the mover. In this case, if the axis of the yoke is eccentric with respect to the guide for regulating the radial position of the mover, the magnetic gap between the mover and the yoke on an outer peripheral side of the mover is also affected by the eccentricity. Therefore, it is necessary to secure a relatively wide magnetic gap between the mover and the yoke on the outer peripheral side of the mover, taking into account the influence of misalignment of the yoke with respect to the guide (bearing).

In this regard, as in the embodiments shown inFIGS.2to4, if the cylindrical guide30, which is capable of realizing the guide function for axially guiding the mover50by the non-magnetic layer34, is fixed to the inner peripheral side of the first yoke14, it is possible to substantially eliminate the influence of misalignment of the first yoke14with respect to the cylindrical guide30. Therefore, a radial clearance tr to be secured between the cylindrical guide30and the mover50is sufficient to have a size that allows for assembly of the mover50. As a result, a magnetic gap between the first stator10and the mover50can be reduced, and the magnetic flux from the first stator10toward the mover50can be increased.

The magnetic gap between the first stator10and the mover50in this case is the sum of the above-described radial clearance tr and the thickness of the non-magnetic layer34.

As shown inFIG.2, a minimum distance d1between the magnetic tube32of the cylindrical guide30and the second stator20(second cylindrical member40) is greater than a minimum distance d2between the mover50at the original position and the second stator20(second cylindrical member40).

By thus satisfying the relation of d1>d2, a magnetic resistance in the gap between the magnetic tube32and the second stator20becomes greater than a magnetic resistance in the gap between the second stator20and the mover50at the original position. As a result, it is possible to increase the magnetic flux flowing between the second stator20and the mover50at the original position.

Conventionally, there has also been proposed a structure in which an annular mover is supported by a yoke from an inner peripheral side via a guide. In this regard, in the solenoid actuator1, since the cylindrical guide30is located radially outward of the mover50, it is possible to secure a large area of the annular magnetic gap between the mover50and the magnetic tube32of the cylindrical guide30, compared to the above-described conventionally proposed structure. This is because the area of the magnetic gap is represented by the product of the axial length and the peripheral length of the magnetic gap, and the peripheral length of the magnetic gap relatively increases when the magnetic gap is formed radially outward. Since the magnetism transfer area (the area of the magnetic gap) between the magnetic tube32and the mover50thus increases, the overall magnetic resistance of the magnetic path4decreases, making it possible to also increase the magnetic flux flowing between the second stator20and the mover50at the original position.

Thus, it is possible to effectively transfer the magnetism between the mover50at the original position and the first stator10and the second stator20(see arrows inFIG.2), and it is possible to realize the compact and high-thrust solenoid actuator1.

Herein, in order to increase the magnetism transfer area between the magnetic tube32and the mover50, it is advantageous to make the cylindrical guide30as long as possible. On the other hand, in order to secure the magnetic flux passing through the mover50at the original position, it is desirable to impose a restriction on the distal end position of the cylindrical guide30such that the above-described relation of d1>d2is established.

In this regard, by making the first through hole15of the first yoke14to have the same diameter between the non-contact region15band the contact region15ain contact with the outer peripheral surface of the cylindrical guide30(magnetic tube32) of the inner wall of the first through hole15as in the embodiment described above with reference toFIG.1, it is possible to adjust the position of the distal end31of the cylindrical guide30with high accuracy. Thus, the cylindrical guide30can sufficiently be made long at the limit where the relation of d1>d2is satisfied, and it is possible to achieve both securing of the magnetism transfer area between the magnetic tube32and the mover50and the increase in magnetic flux passing through the mover50at the original position.

In some embodiments, as shown inFIGS.2to4, the cylindrical guide30axially extends toward the second stator20beyond a distal end position X_yoke of the first yoke14. The minimum distance d1between the magnetic tube32of the cylindrical guide30and the second stator20(second cylindrical member40) may be smaller than a minimum distance d3between the first yoke14and the second stator20(second cylindrical member40).

By extending the cylindrical guide30toward the second stator20beyond the distal end position X of the first yoke14, it becomes easier to secure the magnetism transfer area between the mover50and the magnetic tube32of the cylindrical guide30, and it is possible to increase the magnetic flux flowing between the second stator20and the mover50at the original position.

Meanwhile, if the distal end of the cylindrical guide30is brought too close to the second stator20, the magnetic flux flowing between the magnetic tube32and the second stator20without via the mover50increases, which may result in a decrease in magnetic flux between the mover50and the second stator20. In this regard, by imposing the restriction on the distal end position of the cylindrical guide30(magnetic tube32) so as to satisfy the above-described relation of d1>d2, it is possible to sufficiently secure the magnetic flux flowing between the mover50at the original position and the second stator20.

In some embodiments, the mover50(plunger52) at the original position (X=0) axially extends toward the second stator20beyond the position of the distal end31of the cylindrical guide30. That is, the distal end portion of the mover50at the original position axially projects from the cylindrical guide30toward the second stator20.

Thus, it becomes easier to establish the above-described relation (d1>d2) where the minimum distance d2between the mover50and the second stator20is smaller than the minimum distance d1between the magnetic tube32and the second stator20.

In the exemplary embodiment shown inFIG.2, the distal end portion of the mover50at the original position (X=0) axially overlaps the second stator20. That is, the distal end portion of the mover50at the original position (X=0) intrudes into the cavity28defined by the second stator20(second cylindrical member40).

Thus, it becomes much easier to establish the above-described relation (d1>d2) where the minimum distance d2between the mover50and the second stator20is smaller than the minimum distance d1between the magnetic tube32and the second stator20.

In the exemplary embodiments shown inFIGS.2to4, the outer peripheral surface of the mover50(plunger52) has a tapered surface56, which is tapered such that the outer diameter decreases toward the distal end, between the distal end and a reference point55.

When the mover50is at an original position X0, the reference point55indicating a boundary of the tapered distal end region (tapered surface56) of the outer peripheral surface of the mover50is located radially inward of the cylindrical guide30, and the minimum distance d2between the second stator20and the mover50at the original position is a distance between the second cylindrical member40and an outer peripheral edge of a distal end surface57of the mover50, as shown inFIG.2.

When the mover50is at the intermediate position X1, an axial position of the reference point55on the outer peripheral surface of the mover50substantially coincides with the distal end position of the cylindrical guide30, and a minimum distance d2′ between the mover50and the second stator20is a distance between the second cylindrical member40and the tapered surface56of the mover50, as shown inFIG.3.

When the mover50is at the maximum stroke position X2, the reference point55indicating the boundary of the tapered distal end region of the outer peripheral surface of the mover50exists in the cavity28formed by the second stator20(second cylindrical member40). At this time, as shown inFIG.4, a minimum distance d2″ between the mover50and the second stator20is a distance between the second cylindrical member40and a region of the outer peripheral surface of the mover50in the rear of the reference point55.

The minimum distance between the mover50and the second stator20decreases as the stroke amount of the mover50increases, and the relation of d2>d2′>d2″ is established.

When the mover50is at the original position (X=0), as shown inFIG.2, the magnetism transfer area between the mover50and the second cylindrical member40is smaller than the magnetism transfer area between the cylindrical guide30and the mover50. Further, the magnetic gap (distance d2) between the mover50and the second cylindrical member40is greater than the magnetic gap between the cylindrical guide30and the mover50(the sum of the radial clearance tr and the thickness of the non-magnetic layer34). Therefore, when the mover50is at the original position (X=0), the magnetic gap between the mover50and the second cylindrical member40, which accounts for most of the magnetic resistance of the entire magnetic path, restricts the magnetic flux flowing through the magnetic path, and the magnetic flux flowing through the magnetic path when the coil3is energized is relatively small.

When the mover50moves to the intermediate position X1, compared to the case of the original position (X=0) shown inFIG.2, an intrusion length of the mover50into the cavity28increases, increasing the magnetism transfer area between the mover50and the second stator20(second cylindrical member40), and increasing the magnetic flux flowing through the magnetic path4. Compared to the case of the original position (X=0) shown inFIG.2, the magnetism transfer area between the cylindrical guide30and the mover50is decreased due to the decrease in axial overlapping length between the cylindrical guide30and the mover50. However, as described above, since the magnetic resistance of the magnetic gap between the mover50and the second cylindrical member40, which accounts for most of the magnetic resistance of the entire magnetic path at the original position (X=0), is reduced, the magnetic flux flowing through the magnetic path4increases as a whole.

When the mover50moves to the maximum stroke position X2, compared to the case of the intermediate position X1shown inFIG.3, the intrusion length of the mover50into the cavity28further increases, increasing the magnetism transfer area between the mover50and the second stator20(second cylindrical member40), and further increasing the magnetic flux flowing through the magnetic path4.

Herein, as the mover50moves from the original position (X=0) toward the maximum stroke position (X=X2), the intrusion length of the mover50into the cavity28increases. Thus, as the stroke amount of the mover50increases, a radial component of a magnetic flux vector from the mover50toward the second stator20(second cylindrical member40) increases and an axial component decreases, which may decrease the thrust of the solenoid actuator.

In this regard, as described above, in the embodiments shown inFIGS.2to4, since the tapered surface56is formed on the outer peripheral surface of the mover50(plunger52), the outer peripheral surface of the mover50approaches the inner peripheral surface of the second stator20(second cylindrical member40) as the stroke amount increases. As a result, it is possible to suppress the decrease in thrust.

Next, a specific structural example of the solenoid actuator1will be described with reference toFIG.5.

Hereinafter, the description of the features described above with reference toFIGS.1to4will be omitted.

FIG.5is a cross-sectional view showing the solenoid actuator according to an embodiment.

As shown inFIG.6, the solenoid actuator1includes the coil3, the first stator10and the second stator20, and the mover50(plunger52).

The coil3is formed by winding a wire composed of a conductor such as copper or copper alloy around a bobbin60. The bobbin60is substantially surrounded by the first stator10and the second stator20. However, the first stator10(first yoke14) is provided with a notch in a partial circumferential range, and a terminal holding portion62of the bobbin60is exposed in the notch of the first yoke14. The terminal holding portion62of the bobbin60is embedded with a proximal end portion of a terminal64. The terminal64is electrically connected to the wire, which constitutes the coil3, in the bobbin60.

Further, in the solenoid actuator1, the coil3and the bobbin60, and the first stator10and the second stator20are integrally molded in a resin mold70and embedded in the resin mold70. The terminal64penetrates the resin mold70from the terminal holding portion62of the bobbin60, projects into a recess72disposed in the resin mold70, and can electrically be connected to an external terminal fitted into the recess72.

The resin mold70may have a projection (not shown) that contacts a rear end51of the mover50(plunger52) located at the original position.

Further, in the present specification, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.

For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.

Further, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.

As used herein, the expressions “comprising”, “including” or “having” one constitutional element is not an exclusive expression that excludes the presence of other constitutional elements.