Vehicle and noncontact power transmission and reception system

A vehicle capable of receiving an electric power in a contactless manner includes a vehicle body and a power reception apparatus. A first region made of aluminum or formed so that a magnetic permeability and an electric resistance thereof are lower than a magnetic permeability and an electric resistance of aluminum, respectively, is provided at a position on one side in a reference direction relative to the power reception apparatus. A space and/or a second region formed so that a magnetic permeability and an electric resistance thereof are higher than the magnetic permeability and the electric resistance of the first region, respectively, is provided at a position on the other side in the reference direction. A winding axis of a power receiving coil is placed at a position deviating toward the one side in the reference direction from a central position in a vehicle width direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2016-247827 filed on Dec. 21, 2016, which is incorporated herein by reference in its entirety including the specification, drawings and abstract.

BACKGROUND

1. Technical Field

This disclosure relates to a vehicle capable of receiving an electric power in a contactless manner from a power transmission apparatus provided outside a vehicle body, and a noncontact power transmission and reception system.

2. Description of Related Art

As described in Japanese Patent Application Publication No. 2012-188116 (JP 2012-188116 A), Japanese Patent Application Publication No. 2013-154815 (JP 2013-154815 A), Japanese Patent Application Publication No. 2013-146154 (JP 2013-146154 A), Japanese Patent Application Publication No. 2013-146148 (JP 2013-146148 A), Japanese Patent Application Publication No. 2013-110822 (JP 2013-110822 A), Japanese Patent Application Publication No. 2013-126327 (JP 2013-126327 A), and International Publication No. 2013/076870, a vehicle capable of receiving an electric power in a contactless manner from a power transmission apparatus provided outside a vehicle body has been developed. The vehicle as described in these documents is provided with a power reception apparatus on a bottom surface side of the vehicle body. When the power reception apparatus receives an electric power from a power transmission apparatus, the vehicle is placed so that the power reception apparatus is opposed to the power transmission apparatus in an up-down direction.

When the electric power is supplied to a power transmission coil of the power transmission apparatus, magnetic fluxes are formed around the power transmission coil. When the magnetic fluxes cross a power receiving coil, the vehicle can receive the electric power through the power reception apparatus. On the bottom surface side of the vehicle body, not only the power reception apparatus but also a metal member such as a muffler (e.g., a magnetic body such as iron or stainless) may be placed near the power reception apparatus (see international Publication No. 2013/076870).

SUMMARY

It is desirable that power transmission and reception be performed in a state where the power transmission coil and the power receiving coil are aligned to each other (e.g., in a state where respective extension lines of their winding axes accord with each other). However, it is also assumed that the vehicle stops in a state where the vehicle deviates from the power transmission apparatus, and because of that, the power transmission and reception is performed in a state where the power transmission coil and the power receiving coil are not aligned to each other.

As has been described at the beginning, a metal member may be placed near the power reception apparatus, for example, such that the metal member is adjacent to the power reception apparatus. In this case, the magnetic fluxes formed around the power transmission coil might cross not only the power receiving coil, but also the metal member. For example, assume that a member (a nonmagnetic material) made of aluminum is placed on a first direction side relative to the power reception apparatus, and an iron member is placed on a second direction side relative to the power reception apparatus, the second direction side being an opposite side to the first direction.

When the power transmission and reception is performed in a state where the power receiving coil deviates toward the first direction side (a side where the aluminum member is positioned) from the power transmission coil only by a specific distance, a first coupling coefficient is obtained. When the power transmission and reception is performed in a state where the power receiving coil deviates from the power transmission coil toward the second direction side (a side where the iron member is positioned) only by the same distance as the specific distance, a second coupling coefficient is obtained. The first coupling coefficient and the second coupling coefficient can be values different from each other.

That is, in a case where a metal member, such as iron or stainless, having a higher magnetic permeability and a higher electric resistance than aluminum is provided near the power reception apparatus, the magnetic fluxes easily pass through the metal member and the magnetic fluxes are guided by the metal member so as to easily reach the power receiving coil. In the meantime, in a case where aluminum or a metal member having a lower magnetic permeability and a lower electric resistance than aluminum is provided near the power reception apparatus, the magnetic fluxes are easily reflected by a surface of the metal member so that the magnetic fluxes can hardly reach the power receiving coil.

In a case where an aluminum member, for example, is placed on the first direction side relative to the power reception apparatus and an iron member, for example, is placed on the second direction side relative to the power reception apparatus, the second direction side being an opposite side to the first direction, a plurality of regions having different magnetic permeabilities and different electric resistances is formed around the power reception apparatus. In such a case, a difference easily occurs between a coupling coefficient obtained when the power receiving coil deviates from the power transmission coil toward the first direction side and a coupling coefficient obtained when the power receiving coil deviates from the power transmission coil toward the second direction side.

When the coupling coefficient varies depending on a positional deviation, a receiving voltage of the power reception apparatus varies accordingly. When the power transmission apparatus performs a constant power control, a current flowing through the power transmission apparatus also varies. This requires a device design that can permit variations in the coupling coefficient caused due to the positional deviation. For example, it is necessary to secure a large rating (withstand voltage range) of the power reception apparatus in advance, it is necessary to secure a large rating (withstand current range) of the power transmission apparatus in advance, it is necessary to secure a large coil linear shape to be used, in advance, and it is necessary to set a large current value to be supplied to the power transmission coil in advance.

This disclosure provides a vehicle and a noncontact power transmission and reception system, each of which is configured such that in a case where regions having different magnetic permeabilities and electric resistances are formed around a power reception apparatus, even if a power receiving coil deviates from a power transmission coil, a variation in a coupling coefficient between the power receiving coil and the power transmission coil is restrained.

A vehicle according to a first aspect of the present disclosure is a vehicle capable of receiving an electric power from a power transmission apparatus in a contactless manner, the power transmission apparatus being placed such that a winding axis of a power transmission coil extends in an up-down direction at a central position of a parking space in a width direction, and the vehicle includes: a vehicle body having a bottom surface; and a power reception apparatus including a power receiving coil configured to receive an electric power from the power transmission coil of the power transmission apparatus in a contactless manner, and a housing in which the power receiving coil is accommodated, the power reception apparatus being provided on a bottom surface side of the vehicle body so that a winding axis of the power receiving coil extends in the up-down direction. When a direction intersecting with the winding axis of the power receiving coil and parallel to a vehicle width direction is assumed a reference direction, a first region made of aluminum or formed so that a magnetic permeability and an electric resistance of the first region are lower than a magnetic permeability and an electric resistance of aluminum, respectively, is provided at a position on one side in the reference direction relative to the housing of the power reception apparatus. A space and/or a second region formed so that a magnetic permeability and an electric resistance of the second region are higher than the magnetic permeability and the electric resistance of the first region is provided at a position on the other side in the reference direction relative to the housing of the power reception apparatus. The winding axis of the power receiving coil is placed at a position deviating toward the one side in the reference direction relative to a central position of the vehicle body in the vehicle width direction.

In the above vehicle, magnetic fluxes formed around the power transmission coil pass near the first region positioned on the one side relative to the winding axis of the power receiving coil and cross the power receiving coil, or pass near the space and/or the second region positioned on the other side relative to the winding axis and cross the power receiving coil. On the first region side positioned on the one side, the magnetic fluxes are easily reflected by the first region in comparison with the space and the second region, and the magnetic fluxes can hardly reach the power receiving coil in comparison with the second region. On the space and/or the second region side positioned on the other side, the magnetic fluxes easily reach the power receiving coil in comparison with the first region.

When a state where the central position of the vehicle body in the vehicle width direction accords with the winding axis of the power transmission coil is assumed an aligned state, the winding axis of the power receiving coil is placed at a position deviating toward the one side from the central position of the vehicle body in the vehicle width direction in the above vehicle. Accordingly, even if noncontact power transmission and reception is performed in the aligned state, or even if noncontact power transmission and reception is performed in a state where the power receiving coil deviates from the power transmission coil in the vehicle width direction, an influence of the first region, positioned on the one side relative to the winding axis of the power receiving coil, with respect to the noncontact power transmission and reception hardly changes, and an influence of the space and/or the second region, positioned on the other side relative to the winding axis of the power receiving coil, with respect to the noncontact power transmission and reception also hardly changes. Accordingly, with the above vehicle, even if the power receiving coil deviates from the power transmission coil in the vehicle width direction, it is possible to restrain variations in a coupling coefficient between the power receiving coil and the power transmission coil.

The vehicle further includes a power storage apparatus including a body case, the body case being placed on the bottom surface of the vehicle body. The housing of the power reception apparatus may be attached to a bottom surface of the body case, and the bottom surface of the body case of the power storage apparatus may have a part constituting the first region. With the above configuration, in a case where the power storage apparatus is placed on the bottom surface side of the vehicle body, even if the power receiving coil deviates from the power transmission coil in the vehicle width direction, it is possible to restrain the variations in the coupling coefficient between the power receiving coil and the power transmission coil.

The vehicle further includes: an engine placed inside the vehicle body; and a muffler connected to the engine and provided on the bottom surface side of the vehicle body. The muffler may have a part constituting the second region. With the above configuration, in a case where the engine is provided and the muffler is placed on the bottom surface side of the vehicle body, even if the power receiving coil deviates from the power transmission coil in the vehicle width direction, it is possible to restrain the variations in the coupling coefficient between the power receiving coil and the power transmission coil.

A noncontact power transmission and reception system according to a second aspect of the present disclosure includes: a power transmission apparatus including a power transmission coil and placed such that a winding axis of the power transmission coil extends in an up-down direction in a parking space; and a vehicle capable of receiving an electric power from the power transmission apparatus in a contactless manner in a state where the vehicle is aligned in the parking space, the vehicle including a vehicle body having a bottom surface, and a power reception apparatus including a power receiving coil configured to receive an electric power from the power transmission coil of the power transmission apparatus in a contactless manner, and a housing in which the power receiving coil is accommodated, the power reception apparatus being provided on the bottom surface of the vehicle body so that a winding axis of the power receiving coil extends in the up-down direction. When a direction intersecting with the winding axis of the power receiving coil and parallel to a vehicle front-rear direction or a vehicle width direction is assumed a reference direction, a first region made of aluminum or formed so that a magnetic permeability and an electric resistance of the first region are lower than a magnetic permeability and an electric resistance of aluminum, respectively, may be provided at a position on one side in the reference direction relative to the housing of the power reception apparatus. A space and/or a second region formed so that a magnetic permeability and an electric resistance of the second region are higher than the magnetic permeability and the electric resistance of the first region, respectively, may be provided at a position on the other side in the reference direction relative to the housing of the power reception apparatus. When the winding axis of the power transmission coil is extended upward to draw a virtual extension line in a state where the vehicle body is aligned in the parking space, the winding axis of the power receiving coil may be placed at a position deviating toward the one side in the reference direction from a position of the extension line.

In the noncontact power transmission and reception system, when a state where a predetermined reference position provided in the vehicle body accords with the winding axis of the power transmission coil is assumed an aligned state, the winding axis of the power receiving coil is placed at a position deviating toward the one side in the reference direction from the reference position of the vehicle body. Accordingly, even if noncontact power transmission and reception is performed in the aligned state, or even if noncontact power transmission and reception is performed in a state where the power receiving coil deviates from the power transmission coil in the reference direction, an influence of the first region, positioned on the one side in the reference direction relative to the winding axis of the power receiving coil, with respect to the noncontact power transmission and reception hardly changes, and an influence of the space and/or the second region, positioned on the other side in the reference direction relative to the winding axis of the power receiving coil, with respect to the noncontact power transmission and reception also hardly changes. Accordingly, with the above vehicle, even if the power receiving coil deviates from the power transmission coil in the reference direction, it is possible to restrain variations in a coupling coefficient between the power receiving coil and the power transmission coil.

With the above configuration, in a case where regions having different magnetic permeabilities and electric resistances are formed around the power reception apparatus, even if the power receiving coil deviates from the power transmission coil, it is possible to restrain the coupling coefficient between the power receiving coil and the power transmission coil from varying, thereby making it possible to achieve noncontact charging efficiency with few variations with respect to a positional deviation.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are described with reference to the drawings. The same reference numeral is assigned to the same component and its equivalent component, and a redundant description may not be repeated.

Referring now toFIGS. 1 to 7, the following describes a vehicle1and a noncontact power transmission and reception system100in Embodiment 1.FIG. 1is a view schematically illustrating the vehicle1and the noncontact power transmission and reception system100.FIG. 2is a circuit diagram schematically illustrating the vehicle1and the noncontact power transmission and reception system100.

InFIG. 1, an arrow U indicates an upper direction in a gravitational direction, and an arrow D indicates a lower direction in the gravitational direction. Arrows F, B indicate a vehicle front-rear direction of the vehicle1. Although not illustrated inFIG. 1, arrows L, R inFIG. 3and the like indicate a vehicle width direction of the vehicle1. The meanings of these arrows are common in all the drawings described below.

Noncontact Power Transmission and Reception System100

Referring now toFIGS. 1 and 2, the noncontact power transmission and reception system100is provided with a vehicle1including a power reception apparatus5, and a power transmission apparatus8. The vehicle1(FIG. 1) includes a vehicle body2, an engine3, a muffler4, and a power storage apparatus6, in addition to the power reception apparatus5. The vehicle body2includes a floor panel2A and wheel assemblies2W, and the floor panel2A has a top surface2B and a bottom surface2C. The engine3is placed inside the vehicle body2, and a front end of the muffler4is connected to the engine3. For convenience of illustration, only a part of the muffler4on a front side is illustrated inFIG. 1. The muffler4is provided on the bottom surface2C side of the vehicle body2, and extends generally along the vehicle front-rear direction (FIG. 3).

The power reception apparatus5includes a housing5A, a power receiving portion5B, and a rectifier5R (FIG. 2), and is provided on the bottom surface2C side of the vehicle body2. The housing5A of the power reception apparatus5is fixed to the bottom surface2C of the vehicle body2via the power storage apparatus6(a body case6A). A technical meaning that the power reception apparatus5is provided on the bottom surface2C side of the vehicle body2includes not only a case where the housing5A of the power reception apparatus5is indirectly fixed to the bottom surface2C of the floor panel2A via the power storage apparatus6, but also a case where the housing5A of the power reception apparatus5is indirectly fixed to the bottom surface2C of the floor panel2A via a metal plate6S illustrated inFIG. 14, and a case where the housing5A of the power reception apparatus5is directly fixed to the bottom surface2C of the floor panel2A.

The power receiving portion5B of the power reception apparatus5includes a power receiving coil5L configured to receive an electric power from a power transmission coil8L of the power transmission apparatus8in a contactless manner, a capacitor5T connected in series to the power receiving coil5L, pieces of ferrite5M,5N (FIG. 3,FIG. 4), and a support plate5G (FIG. 4), which are all accommodated in the housing5A. An LC resonance circuit is constituted by the power receiving coil5L and the capacitor5T. A resonant frequency of the power receiving portion5B of the power reception apparatus5and a resonant frequency of a power transmission portion8B of the power transmission apparatus8are configured to be substantially the same. The rectifier5R (FIG. 2) of the power reception apparatus5converts an alternating-current power that the power receiving portion5B receives from the power transmission portion8B, into a direct-current power, and supplies the power to the power storage apparatus6.

The power storage apparatus6is also placed on the bottom surface2C side of the vehicle body2. The power storage apparatus6includes the body case6A. The body case6A has a bottom surface6B, and the power reception apparatus5is placed on the bottom surface6B side of the power storage apparatus6. The power reception apparatus5and the power storage apparatus6are electrically connected to each other by a wiring member (not shown). The wiring member transmits the direct-current power generated by the rectifier5R (FIG. 2) from the power reception apparatus5to the power storage apparatus6, or transmits a low-voltage signal between the power reception apparatus5and the power storage apparatus6.

The power transmission apparatus8includes a housing8A, the power transmission portion8B, and a converter8R (FIG. 2), and is provided within a parking space9A (FIG. 1). The power transmission portion8B includes the power transmission coil8L, a capacitor8T connected in series to the power transmission coil8L, pieces of ferrite8M,8N (FIG. 4), and a support plate8G (FIG. 4), which are all accommodated inside the housing8A. An LC resonance circuit is constituted by the power transmission coil8L and the capacitor8T. A Q value of the LC resonance circuit on the power transmission apparatus8side and a Q value of the LC resonance circuit on the power reception apparatus5side are both 100 or more, for example. The converter8R (FIG. 2) adjusts a frequency and a voltage of the alternating-current power supplied from the power supply9, and supplies the alternating-current power to the power transmission portion8B. When the alternating-current power is supplied to the power transmission portion8B, magnetic fluxes are formed around the power transmission coil8L.

FIG. 3is a plan view illustrating the floor panel2A of the vehicle1(the vehicle body2) in the noncontact power transmission and reception system100, and the muffler4, the power reception apparatus5, the power storage apparatus6, and the like provided on the bottom surface2C side of the floor panel2A, and illustrates a state observed when the bottom surface2C of the vehicle1is viewed from the lower side in the gravitational direction.FIG. 4is a sectional view taken along an arrow IV-IV inFIG. 3.

With reference toFIGS. 1, 3, 4, the power transmission apparatus8is placed inside the parking space9A (FIG. 1) having a predetermined width. A width direction in the parking space9A corresponds to a vehicle width direction of the vehicle1. The parking space9A is provided with a shoe9B (FIG. 1) and mark lines LNR, LNL (FIG. 3). The power transmission apparatus8is placed so that a winding axis (see a winding axis O1inFIG. 3) of the power transmission coil8L extends in the up-down direction (the gravitational direction) at a central position (exactly at a central position between the mark lines LNR, LNL) in the width direction in the parking space9A. Also in terms of the vehicle1, the power reception apparatus5is provided on the bottom surface2C side of the vehicle body2so that a winding axis (see a winding axis O2inFIG. 3) of the power receiving coil5L extends in the up-down direction.

The vehicle1is put into the parking space9A and aligned in the vehicle front-rear direction and in the vehicle width direction, by use of the shoe9B (FIG. 1), the mark lines LNR, LNL (FIG. 3), and the like. The alignment may be performed by a control operation using a sensor, a camera, or the like, or may be performed by a manual operation of a driver. The alignment may be performed by the control operation and the manual operation in combination. In a state where the vehicle1is aligned in the parking space9A, the vehicle1can receive an electric power from the power transmission apparatus8through the power reception apparatus5in a contactless manner.

Detailed Configuration of Vehicle1

Referring now toFIGS. 3 and 4, the vehicle body2(the floor panel2A) has the bottom surface2C. The bottom surface2C of the vehicle body2has a central position C1positioned in the center in the vehicle width direction. In the vehicle width direction, a distance W1between the central position C1and a side surface2L positioned on an arrow L side of the vehicle body2is equal to a distance W2between the central position C1and a side surface2R positioned on an arrow R side of the vehicle body2.

Power Storage Apparatus6

The power storage apparatus6is placed on the bottom surface2C side of the vehicle body2(the floor panel2A). A power storage element (not shown) is accommodated inside the body case6A of the power storage apparatus6. The body case6A includes a top surface (FIG. 4), a bottom surface6B, a front wall6C (FIG. 3), a side wall6D, a rear wall6E (FIG. 3), and a side wall6F, and has a box shape as a whole. The top surface of the body case6A is fixed to the bottom surface2C of the floor panel2A by use of bolts or the like (not shown). The housing5A of the power reception apparatus5is fixed to the bottom surface6B of the body case6A via a fixing member5H (FIG. 4).

The front wall6C (FIG. 3) and the rear wall6E of the body case6A have a shape extending along the vehicle width direction. The side walls6D,6F of the body case6A have a shape extending along the vehicle front-rear direction. The side wall6F of the body case6A is positioned on the arrow L side (a side closer to the side surface2L) relative to the central position C1. The side wall6D of the body case6A is positioned on the arrow R side (a side closer to the side surface2R) relative to the central position C1.

The body case6A of the power storage apparatus6is placed at a position offset to the arrow L side (the side closer to the side surface2L) relative to the central position C1as a whole, so as to allow the muffler4to be placed. That is, in the vehicle width direction, a distance between the central position C1and the side wall6F of the body case6A is longer than a distance between the central position C1and the side wall6D of the body case6A.

Here, in the vehicle width direction, a width of the bottom surface6B of the body case6A is larger than a width of the housing5A of the power reception apparatus5. The bottom surface6B of the body case6A has exposed portions6B1,6B2. The exposed portions6B1,6B2are parts of the bottom surface6B of the power storage apparatus6and are positioned so as to be adjacent to the housing5A of the power reception apparatus5in the vehicle width direction when the bottom surface6B of the power storage apparatus6is planarly viewed from the lower side.

The exposed portion6B1is a part with hatching directed toward a right upper side inFIG. 3, and is positioned on one side (a side closer to the side surface2L) in the vehicle width direction relative to the housing5A of the power reception apparatus5. The exposed portion6B2is a part with hatching directed toward a right lower side inFIG. 3, and is positioned on the other side (a side closer to the side surface2R) in the vehicle width direction relative to the housing5A of the power reception apparatus5. A width of the exposed portion6B2is narrower than a width of the exposed portion6B1.

First Region R1

A member constituting the bottom surface6B of the body case6A is, for example, aluminum. Alternatively, the bottom surface6B of the body case6A can be constituted by a member having a lower magnetic permeability and a lower electric resistance than a magnetic permeability and an electric resistance of aluminum, respectively. In the present embodiment, the exposed portion6B1of the power storage apparatus6(the bottom surface6B of the body case6A) constitutes a first region R1. The first region R1is made of aluminum, or is formed so that a magnetic permeability and an electric resistance are lower than the magnetic permeability and the electric resistance of aluminum. A technical meaning of the first region R1will be described later.

Power Reception Apparatus5

The housing5A (FIG. 4) of the power reception apparatus5includes a main body5J opened downward, and a cover5K configured to close the opening of the main body5J. The main body5J is made of a metal member, and the cover5K is made of a member, such as resin, through which magnetic fluxes can be passed. The main body5J and the cover5K form a box shape as a whole, and have a top surface, a bottom surface, a front wall5C (FIG. 3), a side wall5D, a rear wall5E, and a side wall5F.

The top surface (FIG. 4) of the housing5A is fixed to the bottom surface6B of the power storage apparatus6via the fixing member5H. A technical meaning that the power reception apparatus5is provided on the bottom surface2C side of the vehicle body2includes such a fixation manner. The front wall5C (FIG. 3) and the rear wall5E of the housing5A have a shape extending along the vehicle width direction. The side walls5D,5F of the housing5A have a shape extending along the vehicle front-rear direction. The side wall5F of the housing5A is positioned on the arrow L side (the side closer to the side surface2L) relative to the central position C1. The side wall5D of the housing5A is positioned on the arrow R side (the side closer to the side surface2R) relative to the central position C1.

Although details are described later, in the present embodiment, the winding axis O2of the power receiving coil5L is placed at a position deviating toward one side in a reference direction CD (here, the side closer to the side surface2L) from the central position C1of the vehicle body2in the vehicle width direction. The reference direction CD as used herein is a direction intersecting with the winding axis O2of the power receiving coil5L and parallel to the vehicle width direction.

In the present embodiment, the housing5A of the power reception apparatus5is also placed at a position offset to the arrow L side (the side closer to the side surface2L) as a whole relative to the central position C1. In the vehicle width direction, a distance between the central position C1and the side wall5F of the housing5A is longer than a distance between the central position C1and the side wall5D of the housing5A. In some embodiments, a feature that the housing5A is placed as described above can be employed because the feature can easily realize a configuration in which the winding axis O2of the power receiving coil5L is placed at a deviating position as described above.

The power receiving portion5B is accommodated in the housing5A. The power receiving portion5B includes the power receiving coil5L, the capacitor5T (FIG. 4), the support plate5G (FIG. 4), and a plurality of pieces of ferrite5M,5N. The support plate5G has a central portion projecting downward, and an outer peripheral portion placed around the central portion. A recessed space is formed on a top side of the central portion of the support plate5G, so that the capacitor5T and the like are placed inside the recessed space.

The plurality of pieces of ferrite5M is arranged annularly on a bottom surface of the central portion of the support plate5G (FIG. 3), and the plurality of pieces of ferrite5N is arranged annularly on a bottom surface of the outer peripheral portion of the support plate5G. The ferrite5M makes contact with an inner peripheral portion of the ferrite5N (FIG. 4). The power receiving coil5L is a so-called spiral coil, and is placed annularly on bottom surfaces of the pieces of ferrite5N so as to surround the pieces of ferrite5M. As described above, the power reception apparatus5is provided on the bottom surface2C side of the vehicle body2, so that the winding axis O2of the power receiving coil5L extends in the up-down direction (in a direction parallel to a vehicle-height direction).

The muffler4is fixed to the bottom surface2C side of the floor panel2A with a fixing member (not shown). In the present embodiment, when the bottom surface2C of the vehicle body2is planarly viewed from the lower side in the gravitational direction, the muffler4is placed at a position adjacent to the housing5A of the power reception apparatus5in the vehicle width direction. More specifically, the muffler4is placed at a position on the other side (the side closer to the side surface2R) in the vehicle width direction relative to the housing5A of the power reception apparatus5.

The muffler4is constituted by an inner pipe, a noise reduction material provided around the inner pipe, and a metal cover provided around the noise reduction material, for example. The metal cover of the muffler4constitutes an outer shell of the muffler4, and is made of a metal member mainly constituted by at least one of iron and stainless, for example.

Second Region R2

With reference toFIG. 4, when the direction intersecting with the winding axis O2of the power receiving coil5L and parallel to the vehicle width direction is assumed the reference direction CD as described above, the first region R1made of aluminum or formed so that the magnetic permeability and the electric resistance are lower than the magnetic permeability and the electric resistance of aluminum, respectively, is provided at a position on the one side (the side closer to the side surface2L) in the reference direction CD relative to the housing5A of the power reception apparatus5.

Meanwhile, a space and/or a second region R2formed so that a magnetic permeability and an electric resistance thereof are higher than the magnetic permeability and the electric resistance of the first region R1, respectively, is provided at a position on the other side (the side closer to the side surface2R) in the reference direction CD relative to the housing5A of the power reception apparatus5. In the present embodiment, in the vehicle width direction, a space S and the exposed portion6B2of the power storage apparatus6(the body case6A) are provided between the muffler4and the side wall5D of the power reception apparatus5(the housing5A). The second region R2is constituted by a part of the muffler4on the lower side (a part of the muffler4, the part opposed to the power transmission coil8L of the power transmission apparatus8), the space S, and the exposed portion6B2. The second region R2is formed such that the magnetic permeability and the electric resistance thereof are higher than the magnetic permeability and the electric resistance of the first region R1, respectively.

A magnetic permeability and an electric resistance of the member constituting the metal cover of the muffler4are higher than the magnetic permeability and the electric resistance of the member (e.g., aluminum) forming the first region R1, respectively. In a case where metal mainly containing iron is employed as the member constituting the metal cover of the muffler4, the metal cover of the muffler4can be made of, for example, pure iron (99.95%), pure iron (99.8%), iron cobalt alloy, permalloy (registered trademark) (Fe—Ni alloy), ferrosilicon (alloy obtained by adding a small amount of silicon to iron), and the like. In a case where metal mainly containing stainless is employed as the member constituting the metal cover of the muffler4, the metal cover of the muffler4can be made of ferritic stainless steel, martensitic stainless steel, and the like.

A magnetic permeability of iron (pure iron (99.95%)) is 2.5×10−1[H/m], and a magnetic permeability of iron (pure iron (99.8%)) is 6.3×10−3[H/m]. A magnetic permeability of iron cobalt alloy is 2.3×10−2[H/m], and a magnetic permeability of permalloy (registered trademark) (Fe—Ni alloy) is 1.0×10−2[H/m]. A magnetic permeability of ferrosilicon (alloy obtained by adding a small amount of silicon to iron) is 5.0×10−3[H/m]. A magnetic permeability of ferritic stainless steel is about not less than 1.26×10−3[H/m] but not more than 2.26×10−3[H/m]. A magnetic permeability of martensitic stainless steel is about not less than 9.42×10−4[H/m] but not more than 1.19×10−3[H/m]. Further, an electric resistance of iron is 1.00×10−7(Ωm), and an electric resistance of stainless is 7.2×10−7(Ωm). On the other hand, a magnetic permeability of aluminum is 1.256×10−6[H/m], and an electric resistance of aluminum is 2.65×10−8(Ωm).

As described above, in the present embodiment, the member constituting the bottom surface6B of the body case6A is aluminum and the exposed portion6B2is also constituted by aluminum. The metal cover of the muffler4is made of a metal material mainly containing at least one of iron and stainless, and has a higher magnetic permeability and a higher electric resistance than the magnetic permeability and the electric resistance of the exposed portion6B2(e.g., aluminum), respectively.

The metal cover of the muffler4has a magnetic permeability higher than the magnetic permeability of aluminum, and magnetic fluxes from the power transmission coil8L easily enter the metal cover and easily pass through the metal cover. In addition to such a property of the metal cover, the metal cover constituting the outer shell of the muffler4has an electric resistance higher than the electric resistance of the exposed portion6B2(e.g., aluminum).

Since the metal cover has a higher electric resistance, when the magnetic fluxes enter the metal cover, an eddy current can hardly flow through an outer layer part of the metal cover. When the eddy current flows, a magnetic field that reflects the magnetic fluxes from the power transmission coil8L is formed around the eddy current. However, since the eddy current can hardly flow through the outer layer part of the metal cover having an electric resistance higher than aluminum, a strength of the magnetic field formed by the eddy current is weak, and the magnetic fluxes to enter the metal cover can hardly be reflected.

In the meantime, the metal such as aluminum constituting the exposed portion6B2has a magnetic permeability lower than the magnetic permeability of iron or stainless, and the magnetic fluxes from the power transmission coil8L can hardly enter the exposed portion6B2and also can hardly pass through the exposed portion6B2. In addition to such a property of the exposed portion6B2, the exposed portion6B2(e.g., aluminum) has an electric resistance lower than the electric resistance of iron or stainless.

Since the exposed portion6B2has a low magnetic permeability, the magnetic fluxes from the power transmission coil8L can hardly enter the exposed portion6B2in the first place. However, when the magnetic fluxes enter the exposed portion6B2, an eddy current easily flows through an outer layer part of the exposed portion6B2, because the exposed portion6B2has a low electric resistance. When the eddy current flows, a magnetic field reflecting the magnetic fluxes from the power transmission coil8L is formed around the eddy current. Since the eddy current easily flows through the outer layer part of the exposed portion6B2having an electric resistance lower than iron or stainless, a strength of the magnetic field formed by the eddy current is strong, and the magnetic fluxes to enter the exposed portion6B2are easily reflected. The properties as described above about the exposed portion6B2are also common to the exposed portion6B1constituting the first region R1.

The space S is provided between the muffler4and the exposed portion6B2having the above properties, so that the second region R2is formed as a whole such that the magnetic permeability and the electric resistance of the second region R2are higher than the magnetic permeability and the electric resistance of the first region R1, respectively. A metal heat insulator made of aluminum, a plating steel sheet, or the like is often placed around the muffler4. However, in a case where the heat insulator has a part adjacent to the power reception apparatus5in the vehicle width direction, the first region R1and the second region R2are formed as a whole such that the magnetic permeability and the electric resistance of the second region R2are higher than the magnetic permeability and the electric resistance of the first region R1, respectively, including such a part. That is, in the present embodiment, regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5.

Power Transmission Apparatus8

The housing8A (FIG. 4) of the power transmission apparatus8includes a main body8J opened upward, and a cover8K configured to close the opening of the main body8J. The main body8J is made of a metal member, and the cover8K is made of a member, such as resin, through whish magnetic fluxes can be passed. The main body8J and the cover8K have a box shape as a whole. The power transmission portion8B is accommodated in the housing8A.

The power transmission portion8B includes the power transmission coil8L, the capacitor8T (FIG. 4), the support plate8G (FIG. 4), and a plurality of pieces of ferrite8M,8N. The support plate8G has a central portion projecting upward, and an outer peripheral portion placed around the central portion. A recessed space is formed on a bottom side of the central portion of the support plate8G, so that the capacitor8T and the like are placed inside the recessed space.

The plurality of pieces of ferrite8M is arranged annularly on a top surface of the central portion of the support plate8G, and the plurality of pieces of ferrite8N is arranged annularly on a top surface of the outer peripheral portion of the support plate8G. The ferrite8M makes contact with an inner peripheral portion of the ferrite8N. The power transmission coil8L is a so-called spiral coil, and is placed annularly on top surfaces of the pieces of ferrite8N so as to surround the pieces of ferrite8M. As described above, the power transmission apparatus8is placed inside the parking space9A (FIG. 1), so that the winding axis O1of the power transmission coil8L extends in the up-down direction (in a direction parallel to the gravitational direction). The winding axis O1of the power transmission coil8L is positioned at a center (exactly a center between the mark lines LNR, LNL illustrated inFIG. 3) of the parking space9A in the width direction.

Noncontact Power Transmission and Reception

In the noncontact power transmission and reception system100, noncontact power transmission and reception is performed between the power transmission apparatus8and the power reception apparatus5of the vehicle1.FIG. 5is a sectional view illustrating a state where the power transmission apparatus8and the power reception apparatus5of the vehicle1perform power transmission and reception in a contactless manner in a state where the vehicle1is aligned in the parking space9A (FIG. 1) (in other words, the central position C1of the vehicle1and the winding axis O1of the power transmission coil8L accord with each other).

The noncontact power transmission and reception system100has a predetermined allowable range as a deviation range allowable between the winding axis O2of the power receiving coil5L and the winding axis O1of the power transmission coil8L. In a case where a deviation amount of the winding axis O2from the winding axis O1falls within the predetermined allowable range, when the power transmission coil8L transmits an electric power to the power receiving coil5L, a transmission efficiency with a predetermine value or more is obtained. In a case where the deviation amount of the winding axis O2from the winding axis O1exceeds the predetermined allowable range, when the power transmission coil8L transmits an electric power to the power receiving coil5L, a transmission efficiency with less than the predetermined value is obtained. In the present embodiment, when the transmission efficiency is less than the predetermined value, the power transmission and reception is not started or is stopped.

In the present embodiment, an exterior shape of the power transmission coil8L wound annularly is larger than an exterior shape of the power receiving coil5L wound annularly. In a case where the power receiving coil5L and the power transmission coil8L have a positional relationship in which the deviation amount of the winding axis O2from the winding axis O1falls within the predetermined allowable range, the whole power receiving coil5L and at least a part of the muffler4are positioned inside the exterior shape of the power transmission coil8L (an outer peripheral edge of the power transmission coil8L) when the muffler4, the power receiving coil5L, and the power transmission coil8L are planarly viewed from the lower side in the gravitational direction.

In the case where the power receiving coil5L and the power transmission coil8L have a positional relationship in which the deviation amount of the winding axis O2from the winding axis O1falls within the predetermined allowable range, at least a part of the first region R1in the present embodiment is positioned inside the exterior shape of the power transmission coil8L (the outer peripheral edge of the power transmission coil8L) when the first region R1is planarly viewed from the lower side in the gravitational direction.

Similarly, in the case where the power receiving coil5L and the power transmission coil8L have a positional relationship in which the deviation amount of the winding axis O2from the winding axis O1falls within the predetermined allowable range, at least a part of the second region R2in the present embodiment is positioned inside the exterior shape of the power transmission coil8L (the outer peripheral edge of the power transmission coil8L) when the second region R2is planarly viewed from the lower side in the gravitational direction.

The magnetic fluxes from the power transmission coil8L hardly reach parts of various members constituting the vehicle1, the parts being positioned outside the exterior shape of the power transmission coil8L (the outer peripheral edge of the power transmission coil8L), for example, when planarly viewed from the lower side in the gravitational direction. Accordingly, an influence of those parts to the noncontact power transmission and reception is small. Further, for example, among the various members constituting the vehicle1, a member positioned on an upper side relative to a central part of the power storage apparatus6(the body case6A) in a thickness direction hardly receives the magnetic fluxes from the power transmission coil8L. Accordingly, an influence of the member to the noncontact power transmission and reception is also small.

A degree of the influence changes depending on a magnitude of an electric power to be supplied to the power transmission coil8L (a magnetic field intensity formed around the power transmission coil8L), a distance between the power reception apparatus5and the power transmission apparatus8, materials or various members constituting the power reception apparatus5and the power transmission apparatus8, a temperature of the atmosphere around the power reception apparatus5and the power transmission apparatus8, and the like. However, among various members constituting the noncontact power transmission and reception system100(the vehicle1and the power transmission apparatus8), parts positioned away from the power transmission coil8L and the power receiving coil5L have little influence to the noncontact power transmission and reception, so those parts shall not be included in the following discussion. The noncontact power transmission and reception performed by use of the power reception apparatus5and the power transmission apparatus8configured as described above will be described with reference toFIGS. 5 to 7.

Aligned State

As illustrated inFIG. 5, in the present embodiment, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the central position C1of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 3)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the central position C1of the vehicle body2toward the one side in the reference direction CD (the arrow L side).

As illustrated inFIG. 5, when the sectional shape along the reference direction CD (FIG. 3) and the gravitational direction is viewed, the power receiving coil5L includes a coil portion5La positioned on the arrow R side and a coil portion5Lb positioned on the arrow L side. Similarly, the power transmission coil8L includes a coil portion8La positioned on the arrow R side and a coil portion8Lb positioned on the arrow L side. In the present embodiment, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other, a distance between the coil portions5La and8La is longer than a distance between the coil portions5Lb and8Lb. Among the magnetic fluxes formed around the power transmission coil8L, an amount (magnetic flux density) of magnetic fluxes reaching the power receiving coil5L and crossing the power receiving coil5L is basically inversely proportional to the distance between the power transmission coil8L and the power receiving coil5L.

Some parts of magnetic fluxes MF1formed around the power transmission coil8L (8Lb) loop back on themselves or are reflected by the exposed portion6B1so as not to cross the power receiving coil5L (5Lb), but the other parts of the magnetic fluxes MF1cross the power receiving coil5L (5Lb).

Some parts of magnetic fluxes MF3formed around the power transmission coil8L (8La) also loop back on themselves or are reflected by the exposed portion6B2so as not to cross the power receiving coil5L (5La), but the other parts of the magnetic fluxes MF3cross the power receiving coil5L (5La).

Some parts of magnetic fluxes MF2formed around the power transmission coil8L (8La) loop back on themselves or enter the metal cover of the muffler4. As described above, the metal cover is made of metal having a high magnetic permeability and a high electric resistance. The magnetic fluxes MF2entering the metal cover flow through the metal cover, and then, are emitted from a surface of the metal cover to outside the metal cover.

A lower part of the metal cover is placed to be adjacent to the power receiving coil5L in the vehicle width direction. Some parts of the magnetic fluxes MF2entering the lower part of the muffler4are emitted toward the power receiving coil5L from the lower part, so as to cross the power receiving coil5L. That is, when there is no muffler4, most of the magnetic fluxes MF2formed around the power transmission coil8L (8La) loop back on themselves and do not cross the power receiving coil5L (5La). In the present embodiment, due to the existence of the lower part of the muffler4(the metal cover), some parts of the magnetic fluxes MF2formed around the power transmission coil8L (8La) are guided toward the power receiving coil5L (5La), so as to cross the power receiving coil5L (5La).

Positional Deviation Toward Arrow L Side

FIG. 6is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side only by a distance DR1, from the state illustrated inFIG. 5. When the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side, the distance between the coil portions5Lb and8Lb is shorter than the case ofFIG. 5, whereas the distance between the coil portions5La and8La is longer than the case ofFIG. 5. The lower part of the muffler4(the metal cover) is positioned above the power transmission coil8L (8La) (positioned inside the exterior shape of the coil portion8La, in a plan view).

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is decreased in comparison with the case ofFIG. 5, and an amount of magnetic fluxes MF1acrossing the power receiving coil5L (5Lb) is increased in comparison with the magnetic fluxes MF1(FIG. 5). In the meantime, an amount of magnetic fluxes MF3aformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is decreased in comparison with the magnetic fluxes MF3(FIG. 5).

Some parts of magnetic fluxes MF2aformed around the power transmission coil8L (8La) are guided by the metal cover of the muffler4so as to cross the power receiving coil5L (5La). As a whole of the noncontact power transmission and reception system100, the amount of the magnetic fluxes MF3ais decreased in comparison with the magnetic fluxes MF3(FIG. 5). However, the amount of the magnetic fluxes MF1ais increased in comparison with the magnetic fluxes MF1(FIG. 5), and the magnetic fluxes MF2athat can cross the power receiving coil5L (5La) exist, so that a coupling coefficient in the case of FIG.6is restrained from being greatly decreased from a coupling coefficient in the case ofFIG. 5.

Positional Deviation Toward Arrow R Side

FIG. 7is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side only by a distance DR2, from the state illustrated inFIG. 5. The distance DR2is generally the same as the distance DR1(FIG. 6). When the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side, the distance between the coil portions5Lb and8Lb is longer than the case ofFIG. 5, whereas the distance between the coil portions5La and8La is shorter than the case ofFIG. 5. Most of the lower part of the muffler4(the metal cover) is not positioned above the power transmission coil8L (8La), and is positioned outside the exterior shape of the coil portion8La, in a plan view.

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is increased in comparison with the case ofFIG. 5, and an amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is decreased in comparison with the magnetic fluxes MF1(FIG. 5). In the meantime, an amount of magnetic fluxes MF3bformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is increased in comparison with the magnetic fluxes MF3(FIG. 5).

Magnetic fluxes formed around the power transmission coil8L (8La) are hardly guided to the metal cover of the muffler4. As a whole of the noncontact power transmission and reception system100, the amount of the magnetic fluxes MF1bis decreased in comparison with the magnetic fluxes MF1(FIG. 5), and a guiding effect by the muffler is hardly obtained. However, the amount of the magnetic fluxes MF3bis increased in comparison with the magnetic fluxes MF3(FIG. 5), so that a coupling coefficient in the case ofFIG. 7is restrained from being greatly decreased from the coupling coefficient in the case ofFIG. 5.

In the present embodiment, as described above, the regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5. In a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the central position C1of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 3)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the central position C1(and the wading axis O1) of the vehicle body2toward the one side (the arrow L side) in the reference direction CD.

With the above configuration, even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side (FIG. 6), or even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side (FIG. 7), it is possible to restrain variations in the coupling coefficient between the power receiving coil5L and the power transmission coil8L, thereby making it possible to achieve noncontact charging efficiency with few variations with respect to a positional deviation. A principle that such an operation and an effect are obtained with the configuration will be described below while comparing the present embodiment 1 with Comparative Example 1.

Comparative Example 1

Referring now toFIGS. 8 to 12, a noncontact power transmission and reception system100A (FIG. 9) and a vehicle1A in Comparative Example 1 are described.FIG. 8is a plan view illustrating the vehicle1A (a vehicle body2), and illustrates a state observed when a bottom surface2C of the vehicle1A is viewed from the lower side in the gravitational direction.FIG. 9is a sectional view taken along a line IX-IX inFIG. 8. Embodiment 1 described above and Comparative Example 1 are different from each other in the following points.

In a case of Comparative Example 1, a winding axis O2is placed at a position where the winding axis O2accords with a central position C1in the reference direction CD. A housing5A is placed such that a central position of the housing5A in the reference direction CD accords with the central position C1of the vehicle body2. A distance between the central position C1and a side wall5F of the housing5A is equal to a distance between the central position C1and a side wall5D of the housing5A.

A width of an exposed portion6B2is narrower in Comparative Example 1 than in Embodiment 1. A width of an exposed portion6B1is wider in Comparative Example 1 than in Embodiment 1. A second region R2in Comparative Example 1 is also formed such that a magnetic permeability and an electric resistance thereof are higher than a magnetic permeability and an electric resistance of a first region R1, respectively, similarly to the second region R2in Embodiment 1.

In Comparative Example 1 (FIG. 9), however, an exposed portion6B1is exposed widely above the power transmission coil8L (8Lb), in comparison with Embodiment 1 (FIG. 5). An influence of reflection of the first region R1to noncontact power transmission and reception is larger in Comparative Example 1 than in Embodiment 1. In the meantime, a relationship between a muffler4placed above the power transmission coil8L (8La) and the power transmission coil8L (8La) is hardly different between Comparative Example 1 and Embodiment 1.

The exposed portion6B2is narrower in Comparative Example 1 than in Embodiment 1. However, as a whole of the second region R2, the existence of the muffler4is dominant both in Comparative Example 1 and Embodiment 1. Accordingly, an influence of the second region R2to noncontact power transmission and reception is hardly different between Comparative Example 1 and Embodiment 1.

Noncontact Power Transmission and Reception

In the noncontact power transmission and reception system100A, the noncontact power transmission and reception is performed between the power transmission apparatus8and a power reception apparatus5of the vehicle1A.FIG. 10is a sectional view illustrating a state where the power transmission apparatus8and the power reception apparatus5of the vehicle1A perform power transmission and reception in a contactless manner in a state where the vehicle1A is aligned in the parking space9A (FIG. 1) (in other words, the central position C1of the vehicle1A, the winding axis O2of a power receiving coil5L, and the winding axis O1of the power transmission coil8L accord with each other).

Aligned State

As illustrated inFIG. 10, in Comparative Example 1, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the central position C1of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 8)), the central position C1, the winding axis O2, and the winding axis O1are placed at a position where they accord with each other. In the state where the power reception apparatus5and the power transmission apparatus8are aligned to each other, a distance between coil portions5La and8La is equal to a distance between coil portions5Lb and8Lb.

An amount of magnetic fluxes MF1formed around the power transmission coil8L (8Lb) and reflected by the first region R1(the exposed portion6B1) is larger in Comparative Example 1 than in Embodiment 1 (FIG. 5). An amount of magnetic fluxes MF1formed around the power transmission coil8L (8Lb) and crossing the power receiving coil5L (5Lb) is smaller in Comparative Example 1 than in Embodiment 1 (FIG. 5).

An amount of magnetic fluxes MF3formed around the power transmission coil8L (8La) and reflected by the exposed portion6B2is smaller in Comparative Example 1 than in Embodiment 1 (FIG. 5). An amount of magnetic fluxes MF3formed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is larger in Comparative Example 1 than in Embodiment 1 (FIG. 5). An amount of magnetic fluxes MF2formed around the power transmission coil8L (8La) and guided toward the power receiving coil5L due to the existence of the lower part of the muffler4(the metal cover) so as to cross the power receiving coil5L is larger in Comparative Example 1 than in Embodiment 1 (FIG. 5).

The amount of the magnetic fluxes MF1is smaller in Comparative Example 1 than in Embodiment 1 (FIG. 5). However, in Comparative Example 1, the winding axis O2accords with the winding axis O1, and as a whole of the noncontact power transmission and reception system100A, a coupling coefficient between the power receiving coil5L and the power transmission coil8L is higher in Comparative Example 1 than in Embodiment 1.

It is desirable that the power transmission and reception be performed in a state where the alignment is performed sufficiently (the winding axes O1, O2accord with each other) so that a high coupling coefficient is obtained. However, it is also assumed that, the vehicle1A stops in a state where the vehicle1A deviates from the power transmission apparatus8, and because of that, the power transmission and reception is performed in a state where the winding axes O1, O2deviate from each other.

Positional Deviation Toward Arrow L Side

FIG. 11is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side only by a distance DR1, from the state illustrated inFIG. 10. When the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side, the distance between the coil portions5Lb and8Lb is shorter than the case ofFIG. 10, whereas the distance between the coil portions5La and8La is longer than the case ofFIG. 10. The lower part of the muffler4(the metal cover) is positioned above the power transmission coil8L (8La) (positioned inside the exterior shape of the coil portion8La, in a plan view).

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is decreased in comparison with the case ofFIG. 10, and an amount of magnetic fluxes MF1acrossing the power receiving coil5L (5Lb) is increased in comparison with the magnetic fluxes MF1(FIG. 10). In the meantime, an amount of magnetic fluxes MF3aformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is decreased in comparison with the magnetic fluxes MF3(FIG. 10).

Some parts of magnetic fluxes MF2aformed around the power transmission coil8L (8La) are guided by the metal cover of the muffler4so as to cross the power receiving coil5L (5La). As a whole of the noncontact power transmission and reception system100A, the amount of the magnetic fluxes MF3ais decreased in comparison with the magnetic fluxes MF3(FIG. 10). However, the amount of the magnetic fluxes MF1ais increased in comparison with the magnetic fluxes MF1(FIG. 10), and the magnetic fluxes MF2athat can cross the power receiving coil5L (5La) exist, so that a coupling coefficient in the case ofFIG. 11is restrained from being greatly decreased from a coupling coefficient in the case ofFIG. 10.

Positional Deviation Toward Arrow R Side

FIG. 12is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side only by a distance DR2, from the state illustrated inFIG. 10. The distance DR2is generally the same as the distance DR1(FIG. 11). When the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side, the distance between the coil portions5Lb and8Lb is longer than the case ofFIG. 10, whereas the distance between the coil portions5La and8La is shorter than the case ofFIG. 10. Most of the lower part of the muffler4(the metal cover) is not positioned above the power transmission coal8L (8La), and is positioned outside the exterior shape of the coil portion8La, in a plan view.

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is increased in comparison with the case ofFIG. 10, and an amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is decreased in comparison with the magnetic fluxes MF1(FIG. 10). In Comparative Example 1, the exposed portion6B1is exposed widely above the power transmission coil8L (8Lb), in comparison with Embodiment 1 (FIG. 7). Accordingly, the amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is remarkedly decreased in Comparative Example 1 in comparison with Embodiment 1.

An amount of magnetic fluxes MF3bformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is increased in comparison with the magnetic fluxes MF3(FIG. 10). Similarly to Embodiment 1 (FIG. 7), the magnetic fluxes formed around the power transmission coil8L (8La) are hardly guided to the metal cover of the muffler4.

Comparison Between Embodiment 1 and Comparative Example 1

A coupling coefficient obtained in a state where the alignment is performed in Embodiment 1 (a state (FIG. 5) where the winding axis O1accords with the central position C1) is referred to as EX1, and a coupling coefficient obtained in a state where the alignment is performed in Comparative Example 1 (a state (FIG. 10) where the winding axis O1accords with the winding axis O2) is referred to as CN1. CN1 is higher than EX1.

In Embodiment 1 and Comparative Example 1, respective coupling coefficients obtained when the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side (FIG. 6,FIG. 11) are referred to as EX1L and CN1L. In Embodiment 1 and Comparative Example 1, respective coupling coefficients obtained when the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side (FIG. 7,FIG. 12) are referred to as EX1R and CN1R.

A variation amount EXV of the coupling coefficient generated when a positional deviation occurs in Embodiment 1 is expressed as (EX1−EX1L)+(EX1−EX1R) and a variation amount CNV of the coupling coefficient generated when a positional deviation occurs in Comparative Example 1 is expressed as (CN1−CN1L)+(CN1−CN1R). Here, the variation amount CNV is larger than the variation amount EXV.

That is, in the noncontact power transmission and reception system100of Embodiment 1, the central position C1and the winding axis O1are intended to accord with each other, while the winding axis O2does not accord with the central position C1, but the winding axis O2is placed at a position offset from the central position C1toward a side closer to the first region R1having a lower magnetic permeability and a lower electric resistance than the second region R2(that is, a side away from the second region R2including the muffler4).

In the noncontact power transmission and reception system100A of Comparative Example 1, the central position C1and the winding axes O1, O2are intended to accord with each other. As a whole of the noncontact power transmission and reception systems100,100A, in terms of the second region R2, the existence of the muffler4is dominant both in Comparative Example 1 and Embodiment 1. Accordingly, an influence of the second region R2to the noncontact power transmission and reception is hardly different between Comparative Example 1 and Embodiment 1. Meanwhile, in terms of the first region R1, an influence of reflection of the first region R1to the noncontact power transmission and reception is larger in Comparative Example 1 than in Embodiment 1.

Accordingly, with the configuration of Embodiment 1, in a case where the regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5, even if the power receiving coil5L deviates from the power transmission coil8L, the variation amount EXV is smaller than the variation amount CNV, so that it is possible to restrain variations in the coupling coefficient in comparison with Comparative Example 1, thereby making it possible to achieve noncontact charging efficiency with few variations with respect to the positional deviation.

FIG. 13is a sectional view illustrating a noncontact power transmission and reception system100B and a vehicle1B in Embodiment 2, and corresponds toFIG. 4in Embodiment 1. Embodiments 1 and 2 are different from each other in the following points.

The vehicle1of Embodiment 1 includes the engine3and the muffler4, and can function as a hybrid vehicle or a plug-in hybrid vehicle. The vehicle1B of Embodiment 2 does not include an engine and a muffler, and can function as an electric vehicle. In the vehicle1B, a projection portion2T is provided on a bottom surface2C side of a vehicle body2(a floor panel2A) so that the projection portion2T is adjacent to a power reception apparatus5in the vehicle width direction.

The projection portion2T is constituted by a metal member mainly containing at least one of iron and stainless, for example. The projection portion2T of the present embodiment is constituted by a member provided integrally with the floor panel2A, as a part of the floor panel2A. Alternatively, the projection portion2T may be constituted by a structural member (a lower arm or a frame) other than the floor panel2A in the vehicle body2.

Similarly to Embodiment 1, a second region R2including such a projection portion2T is positioned on the other side (the arrow R side) in the reference direction CD (seeFIG. 3and so on) relative to a housing5A of the power reception apparatus5, and is formed such that a magnetic permeability and an electric resistance of the second region R2are higher than a magnetic permeability and an electric resistance of a first region R1, respectively. Even with the vehicle1B and the noncontact power transmission and reception system100B configured as described above, the projection portion2T gives an action similar to the muffler4to noncontact power transmission and reception, so that it is possible to obtain an operation and an effect similar to Embodiment 1.

FIG. 14is a sectional view illustrating a noncontact power transmission and reception system100C and a vehicle1C in Embodiment 3, and corresponds toFIG. 4in Embodiment 1. Embodiments 1 and 3 are different from each other in the following points.

In the vehicle1of Embodiment 1, the power reception apparatus5is fixed to the bottom surface2C side of the vehicle body2(the floor panel2A) via the power storage apparatus6. In the vehicle1C of Embodiment 3, a power reception apparatus5is fixed to a bottom surface2C side of a vehicle body2(a floor panel2A) via a metal plate6S. A power storage apparatus6may be placed on the bottom surface2C side of the vehicle body2(the floor panel2A) or may be provided inside the vehicle body2(on a top side of the floor panel2A), as needed.

The metal plate6S is constituted by a member made of aluminum, for example. A bottom surface6T of the metal plate6S functions similarly to the bottom surface6B of the power storage apparatus6of Embodiment 1, with respect to noncontact power transmission and reception. An exposed portion6T1functions similarly to the exposed portion6B1of Embodiment 1, and an exposed portion6T2functions similarly to the exposed portion6B2of Embodiment 1.

Also in terms of a first region R1including such an exposed portion6T1and a second region R2including such an exposed portion6T2, the second region R2is formed such that a magnetic permeability and an electric resistance thereof are higher than a magnetic permeability and an electric resistance of the first region R1, respectively. Even with the vehicle1C and the noncontact power transmission and reception system100C configured as described above, the exposed portions6T1,6T2give actions similar to the exposed portions6B1,6B2to noncontact power transmission and reception, so that it is possible to obtain an operation and an effect similar to those in Embodiment 1.

Modifications of Embodiments 1 to 3

In Embodiments 1 to 3, the space S is included as a constituent of the second region R2. The space S is not an essential constituent. For example, in the configuration of Embodiment 1 or Embodiment 3 (FIG. 14), a heat insulation material may be provided between the power reception apparatus5and the muffler4so as to bury the space therebetween. In the configuration of Embodiment 2 (FIG. 13), the projection portion2T may make contact with the body case6A of the power storage apparatus6.

Even in a case where the second region R2does not include the space S as the constituent, when the second region R2is formed such that the magnetic permeability and the electric resistance thereof are higher than the magnetic permeability and the electric resistance of the first region R1, respectively, it is possible to obtain operations and effects similar to those in Embodiments 1 to 3.

Referring now toFIGS. 15 to 19, the following describes a vehicle1D and a noncontact power transmission and reception system100D in Embodiment 4.FIG. 15is a plan view illustrating a floor panel2A of the vehicle1D (a vehicle body2) in the noncontact power transmission and reception system100D, and a power reception apparatus5, a power storage apparatus6, and the like provided on a bottom surface2C side of the floor panel2A, and illustrates a state observed when the bottom surface2C of the vehicle1D is viewed from the lower side in the gravitational direction.FIG. 16is a sectional view taken along an arrow XVI-XVI inFIG. 15. Embodiments 1 and 4 are different from each other in the following points.

The vehicle1D of Embodiment 4 does not include an engine and a muffler, and can function as an electric vehicle. The power reception apparatus5and the power storage apparatus6are placed between wheel assemblies2W,2W (two front wheels). The power reception apparatus5and the power storage, apparatus6may be placed between two rear wheels (not shown). A space S is provided on the arrow R side relative to a side wall5D of the power reception apparatus5and on the arrow R side relative to a side wall6D of the power storage apparatus6.

A second region R2includes the space S and an exposed portion6B2, but does not include a muffler as a constituent. The space S and the exposed portion6B2constituting the second region R2are, as a whole, positioned on the other side (a side closer to a side surface2R) in the reference direction CD relative to a housing5A of the power reception apparatus5, and is formed such that a magnetic permeability and an electric resistance of the second region R2are higher than a magnetic permeability and an electric resistance of a first region R1, respectively.

Noncontact Power Transmission and Reception

In the noncontact power transmission and reception system100D, noncontact power transmission and reception is performed between the power transmission apparatus8and the power reception apparatus5of the vehicle1D.FIG. 17is a sectional view illustrating a state where the power transmission apparatus8and the power reception apparatus5of the vehicle1D perform power transmission and reception in a contactless manner in a state where the vehicle1D is aligned in the parking space9A (seeFIG. 1) (in other words, a central position C1of the vehicle1D accords with the winding axis O1of the power transmission coil8L).

Aligned State

As illustrated inFIG. 17, in the present embodiment, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the central position C1of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 15)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the central position C1of the vehicle body2toward the one side (the arrow L side) in the reference direction CD.

Magnetic fluxes MF1formed around the power transmission coil8L (8Lb) cross the power receiving coil5L (5Lb), similarly to Embodiment 1. Magnetic fluxes MF3formed around the power transmission coil8L (8La) pass through the space S and cross the power receiving coil5L (5La) without being affected by the muffler, unlike Embodiment 1.

Positional Deviation Toward Arrow L Side

FIG. 18is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side only by a distance DR1, from the state illustrated inFIG. 17. Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is decreased in comparison with the case ofFIG. 17, and an amount of magnetic fluxes MF1acrossing the power receiving coil5L (5Lb) is increased in comparison with the magnetic fluxes MF1(FIG. 17). In the meantime, an amount of magnetic fluxes MF3aformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is decreased in comparison with the magnetic fluxes MF3(FIG. 17).

Positional Deviation Toward Arrow R Side

FIG. 19is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side only by a distance DR2, from the state illustrated inFIG. 17. The distance DR2is generally the same as the distance DR1(FIG. 18). The space S is positioned above the power transmission coil8L (8La).

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is increased in comparison with the case ofFIG. 17, and an amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is decreased in comparison with the magnetic fluxes MF1(FIG. 17). In the meantime, an amount of magnetic fluxes MF3bformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is increased in comparison with the magnetic fluxes MF3(FIG. 17).

In the present embodiment, as described above, the regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5, and in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the central position C1of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 15)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the central position C1(and the winding axis O1) of the vehicle body2toward the one side (the arrow L side) in the reference direction CD.

With the above configuration, even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side (FIG. 18), or even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side (FIG. 19), it is possible to restrain variations in a coupling coefficient between the power receiving coil5L and the power transmission coil8L, thereby making it possible to achieve noncontact charging efficiency with few variations with respect to a positional deviation. A principle that such an operation and an effect are obtained with the configuration will be described below while comparing Comparative Example 2 with Embodiment 4.

Comparative Example 2

Referring now toFIGS. 20 to 24, a noncontact power transmission and reception system100E (FIG. 21) and a vehicle1E in Comparative Example 2 are described.FIG. 20is a plan view illustrating the vehicle1E (a vehicle body2), and illustrates a state observed when a bottom surface2C of the vehicle1E is viewed from the lower side in the gravitational direction.FIG. 21is a sectional view taken along an arrow XXI-XXI inFIG. 20. Embodiment 4 described above and Comparative Example 2 are different from each other in the following points.

In a case of Comparative Example 2, a winding axis O2is placed at a position where the winding axis O2accords with a central position C1in the reference direction CD. A housing5A is placed such that a central position of the housing5A in the reference direction CD accords with the central position C1of the vehicle body2. A width of an exposed portion6B2is narrower in Comparative Example 2 than that in Embodiment 4. A width of an exposed portion6B1is wider in Comparative Example 2 than in Embodiment 4. A second region R2in Comparative Example 2 is also formed such that a magnetic permeability and an electric resistance thereof are higher than a magnetic permeability and an electric resistance of a first region R1, respectively, similarly to the second region R2in Embodiment 4.

In Comparative Example 4 (FIG. 21), however, the exposed portion6B1is exposed widely above the power transmission coil8L (8Lb), in comparison with Embodiment 4 (FIG. 16). An influence of reflection of the first region R1to noncontact power transmission and reception is larger in Comparative Example 2 than Embodiment 4. In the meantime, a relationship between the space S positioned above the power transmission coil8L (8La) and the power transmission coil8L (8La) is hardly different between Comparative Example 2 and Embodiment 4.

The exposed portion6B2is narrower in Comparative Example 2 than in Embodiment 4. However, as a whole of the second region R2, the existence of the space S is dominant both in Comparative Example 2 and Embodiment 4. Accordingly, an influence of the second region R2to the noncontact power transmission and reception is hardly different between Comparative Example 2 and Embodiment 4.

Noncontact Power Transmission and Reception

In the noncontact power transmission and reception system100E, noncontact power transmission and reception is performed between the power transmission apparatus8and the power reception apparatus5of the vehicle1E.FIG. 22is a sectional view illustrating a state where the power transmission apparatus8and the power reception apparatus5of the vehicle1E perform power transmission and reception in a contactless manner in a state where the vehicle1E is aligned in the parking space9A (FIG. 1) (in other words, a central position C1of the vehicle1E, a winding axis O2of a power receiving coil5L, and the winding axis O1of the power transmission coil8L accord with each other).

Aligned State

As illustrated inFIG. 22, in Comparative Example 2, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the central position C1of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 20)), the central position C1, the winding axis O2, and the winding axis O1are placed at a position where they accord with each other. In a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other, a distance between coil portions5La and8La is equal to a distance between coil portions5Lb and8Lb.

An amount of magnetic fluxes MF1formed around the power transmission coil8L (8Lb) and reflected by the first region R1(the exposed portion6B1) is larger in Comparative Example 2 than in Embodiment 4 (FIG. 17). An amount of magnetic fluxes formed around the power transmission coil8L (8Lb) and crossing the power receiving coil5L (5Lb) is smaller in Comparative Example 2 than in Embodiment 4 (FIG. 17).

An amount of magnetic fluxes MF3formed around the power transmission coil8L (8La) and reflected by the exposed portion6B2is smaller in Comparative Example 2 than in Embodiment 4 (FIG. 17). An amount of magnetic fluxes MF3formed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is larger in Comparative Example 2 than in Embodiment 4 (FIG. 17).

The amount of the magnetic fluxes MF1is smaller in Comparative Example 2 than in Embodiment 4 (FIG. 17). However, in Comparative Example 2, the winding axis O2accords with, the winding axis O1, and as a whole of the noncontact power transmission and reception system100E, a coupling coefficient between the power receiving coil5L and the power transmission coil8L is higher in Comparative Example 2 than in Embodiment 4.

It is desirable that power transmission and reception be performed in a state where the alignment is performed sufficiently (the winding axes O1, O2accord with each other) so that a high coupling coefficient is obtained. However, it is also assumed that the vehicle1E stops in a state where the vehicle1E deviates from the power transmission apparatus8, and because of that, the power transmission and reception is performed in a state where the winding axes O1, O2deviate from each other.

Positional Deviation Toward Arrow L Side

FIG. 23is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side only by a distance DR1, from the state illustrated inFIG. 22. Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is decreased in comparison with the case ofFIG. 22, and an amount of magnetic fluxes MF1acrossing the power receiving coil5L (5Lb) is increased in comparison with the magnetic fluxes MF1(FIG. 22). In the meantime, an amount of magnetic fluxes MF3aformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is decreased in comparison with the magnetic fluxes MF3(FIG. 22).

Positional Deviation Toward Arrow R Side

FIG. 24is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side only by a distance DR2, from the state illustrated inFIG. 22. The distance DR2is generally the same as the distance DR1(FIG. 23). The space S is placed above the power transmission coil8L (8La).

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is increased in comparison with the case ofFIG. 22, and an amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is decreased in comparison with the magnetic fluxes MF1(FIG. 22). In Comparative Example 2, the exposed portion6B1is exposed widely above the power transmission coil8L (8Lb), in comparison with Embodiment 4 (FIG. 19). Accordingly, the amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is remarkedly decreased in Comparative Example 2 in comparison with Embodiment 4. An amount of magnetic fluxes MF3bformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is increased in comparison with the magnetic fluxes MF3(FIG. 22).

Comparison Between Embodiment 4 and Comparative Example 2

A coupling coefficient obtained in a state where the alignment is performed in Embodiment 4 (a state (FIG. 16) where the winding axis O1accords with the central position C1) is referred to as EX1, and a coupling coefficient obtained in a state where the alignment is performed in Comparative Example 2 (a stateFIG. 22) where the winding axis O1accords with the winding axis O2) is referred to as CN1. CN1 is higher than EX1.

In Embodiment 4 and Comparative Example 2, respective coupling coefficients obtained when the power receiving coil5L deviates from the power transmission coil8L toward the arrow L side (FIG. 18,FIG. 23) are referred to as EX1L and CN1L. In Embodiment 4 and Comparative Example 2, respective coupling coefficients obtained when the power receiving coil5L deviates from the power transmission coil8L toward the arrow R side (FIG. 19,FIG. 24) are referred to as EX1R and CN1R.

A variation amount EXV of the coupling coefficient generated when a positional deviation occurs in Embodiment 4 is expressed as (EX1−EX1L)+(EX1−EX1R) and a variation amount CNV of the coupling coefficient generated when a positional deviation occurs in Comparative Example 2 is expressed as (CN1−CN1L)+(CN1−CN1R). Here, the variation amount CNV is larger than the variation amount EXV.

That is, in the noncontact power transmission and reception system100D of Embodiment 4, the central position C1and the winding axis O1are intended to accord with each other, while the winding axis O2does not accord with the central position C1, but the winding axis O2is placed at a position offset from the central position C1toward a side closer to the first region R1having a lower magnetic permeability and a lower electric resistance than the second region R2(that is, a side away from the second region R2).

In the noncontact power transmission and reception system100E of Comparative Example 2, the central position C1and the winding axes O1, O2are intended to accord with each other. As a whole of the noncontact power transmission and reception systems100D,100E, in terms of the second region R2, the existence of the space S is dominant both in Comparative Example 2 and Embodiment 4. Accordingly, an influence of the second region R2to the noncontact power transmission and reception is hardly different between Comparative Example 2 and Embodiment 4. Meanwhile, in terms of the first region R1, an influence of reflection of the first region R1to the noncontact power transmission and reception is larger in Comparative Example 2 than in Embodiment 4.

Accordingly, with the configuration of Embodiment 4, in a case where the regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5, even if the power receiving coil5L deviates from the power transmission coil8L, the variation amount EXV is smaller than the variation amount CNV, so that it is possible to restrain the coupling coefficient from varying in comparison with Comparative Example 2, thereby making it possible to achieve noncontact charging efficiency with few variations with respect to the positional deviation.

Referring now toFIGS. 25 to 29, the following describes a vehicle1F and a noncontact power transmission and reception system100F in Embodiment 5.FIG. 25is a plan view illustrating a floor panel2A of the vehicle1F (a vehicle body2) in the noncontact power transmission and reception system100F, and a power reception apparatus5, a power storage apparatus6, and the like provided on a bottom surface2C side of the floor panel2A, and illustrates a state observed when the bottom surface2C of the vehicle1F is viewed from the lower side in the gravitational direction.FIG. 26is a sectional view taken along an arrow XXVI-XXVI inFIG. 25. Embodiments 4 and 5 are different from each other in the following points.

The vehicle1F is put into the parking space9A (seeFIG. 1), and aligned in the vehicle front-rear direction and in the vehicle width direction, by use of the shoe9B (seeFIG. 1), the mark lines LNR, LNL (seeFIG. 3), and the like. In the noncontact power transmission and reception system100F, noncontact power transmission and reception is performed between the power transmission apparatus8and a power reception apparatus5of the vehicle1F.

In a state where the vehicle1F is aligned in the parking space9A (FIG. 1), a reference position C2(FIG. 26) of the vehicle1F and the winding axis O1of the power transmission coil8L accord with each other. The reference position C2is a position near the power reception apparatus5and can be set to a given point in the vehicle front-rear direction. In Embodiment 5, the vehicle1F is intended to be aligned in the parking space9A (FIG. 1) so that the reference position C2and the winding axis O1accord with each other.

In the vehicle1F of Embodiment 5, a winding axis O2of a power receiving coil5L is placed at a position deviating from the reference position C2(FIG. 26) toward one side (an arrow B side) in a reference direction CD. The reference direction CD as used herein is a direction intersecting with the winding axis O2of the power receiving coil5L and parallel to the vehicle front-rear direction. A housing5A of the power reception apparatus5is placed at a position offset to the arrow B side (a vehicle rear side) as a whole relative to the reference position C2.

A bottom surface6B of the power storage apparatus6(a body case6A) has exposed portions6B1,6B2. In Embodiment 5, the exposed portions6B1,6B2are parts of the bottom surface6B of the power storage apparatus6and are positioned so as to be adjacent to the housing5A of the power reception apparatus5in the vehicle front-rear direction when the bottom surface6B of the power storage apparatus6is planarly viewed from the lower side.

The exposed portion6B1is a part with hatching directed toward a right upper side inFIG. 25, and is positioned on the one side (the arrow B side) in the vehicle front-rear direction (the reference direction CD) relative to the housing5A of the power reception apparatus5. The exposed portion6B2is a part with hatching directed toward a right lower side inFIG. 25, and is positioned on the other side (an arrow F side) in the vehicle front-rear direction (the reference direction CD) relative to the housing5A of the power reception apparatus5. A width of the exposed portion6B2is narrower than a width of the exposed portion6B1.

The exposed portion6B1of the power storage apparatus6(the bottom surface6B of the body case6A) constitutes a first region R1. The first region R1is made of aluminum, or is formed so that a magnetic permeability and an electric resistance are lower than the magnetic permeability and the electric resistance of aluminum.

A space and/or a second region R2formed so that a magnetic permeability and an electric resistance are higher than the magnetic permeability and the electric resistance of the first region R1is provided at a position on the other side (the arrow F side) in the reference direction CD relative to the housing5A of the power reception apparatus5. In the present embodiment, a projection portion2T is provided on a bottom surface2C side of the vehicle body2(the floor panel2A) so that the projection portion2T is adjacent to the power reception apparatus5in the vehicle front-rear direction.

The projection portion2T is constituted by a metal member mainly containing at least one of iron and stainless, for example. The projection portion2T of the present embodiment is constituted by a member provided integrally with the floor panel2A, as a part of the floor panel2A. Alternatively, the projection portion2T may be constituted by a structural member (a lower arm or a frame) other than the floor panel2A in the vehicle body2.

The second region R2including such a projection portion2T is positioned on the other side (the arrow F side) in the reference direction CD (seeFIG. 25and so on) relative to the housing5A of the power reception apparatus5, and is formed such that a magnetic permeability and an electric resistance thereof are higher than the magnetic permeability and the electric resistance of the first region R1, respectively.

Noncontact Power Transmission and Reception

In the noncontact power transmission and reception system100F, noncontact power transmission and reception is performed between the power transmission apparatus8and the power reception apparatus5of the vehicle1F.FIG. 27is a sectional view illustrating a state where the power transmission apparatus8and the power reception apparatus5of the vehicle1F perform power transmission and reception in a contactless manner in a state where the vehicle1F is aligned in the parking space9A (FIG. 1) (in other words, the reference position C2of the vehicle1F and the winding axis O1of the power transmission coil8L accord with each other).

Aligned State

As illustrated inFIG. 27, in Embodiment 5, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the reference position C2of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 25)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the reference position C2of the vehicle body2toward the one side (the arrow F side) in the reference direction CD. That is, when the winding axis O1of the power transmission coil8L is extended upward to draw a virtual extension line (corresponding to a straight line extending in the up-down direction through the reference position C2) in a state where the vehicle body2is aligned in the parking space, the winding axis O2of the power receiving coil5L is placed at a position deviating toward the one side (the arrow F side) in the reference direction CD from a position of the extension line.

Magnetic fluxes MF1formed around the power transmission coil8L (8Lb) cross the power receiving coil5L (5Lb). Magnetic fluxes MF3formed around the power transmission coil8L (8La) cross the power receiving coil5L (5La). Magnetic fluxes MF2formed around the power transmission coil8L (8La) are guided toward the power receiving coil5L (5La) due to the existence of a lower part of the projection portion2T, so as to cross the power receiving coil5L (5La).

Positional Deviation Toward Arrow L Side

FIG. 28is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow B side only by a distance DR1, from the state illustrated inFIG. 27. The lower part of the projection portion2T is positioned above the power transmission coil8L (8La) (positioned inside the exterior shape of the coil portion8La, in a plan view).

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is decreased in comparison with the case ofFIG. 27, and an amount of magnetic fluxes MF1acrossing the power receiving coil5L (5Lb) is increased in comparison with the magnetic fluxes MF1(FIG. 27). In the meantime, an amount of magnetic fluxes MF3aformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is decreased in comparison with the magnetic fluxes MF3(FIG. 27).

Some parts of magnetic fluxes MF2aformed around the power transmission coil8L (8La) are guided by the projection portion2T so as to cross the power receiving coil5L (5La). As a whole of the noncontact power transmission and reception system100F, the amount of the magnetic fluxes MF3ais decreased in comparison with the magnetic fluxes MF3(FIG. 27). However, the amount of the magnetic fluxes MF1ais increased in comparison with the magnetic fluxes MF1(FIG. 27), and the magnetic fluxes MF2athat can cross the power receiving coil5L (5La) exist, so that a coupling coefficient in the case ofFIG. 28is restrained from being greatly decreased from a coupling coefficient in the case ofFIG. 27.

Positional Deviation Toward Arrow R Side

FIG. 29is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow F side only by a distance DR2, from the state illustrated inFIG. 27. The distance DR2is generally the same as the distance DR1(FIG. 28). Most of the lower part of the projection portion2T is not positioned above the power transmission coil8L (8La), but is positioned outside the exterior shape of the coil portion8La, in a plan view.

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is increased in comparison with the case ofFIG. 27, and an amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is decreased in comparison with the magnetic fluxes MF1(FIG. 27). In the meantime, an amount of magnetic fluxes MF3bformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is increased in comparison with the magnetic fluxes MF3(FIG. 27).

The magnetic fluxes formed around the power transmission coil8L (8La) are hardly guided to the projection portion2T. As a whole of the noncontact power transmission and reception system100F, the amount of the magnetic fluxes MF1bis decreased in comparison with the magnetic fluxes MF1(FIG. 27), and a guiding effect by the projection portion2T is hardly obtained. However, the amount of the magnetic fluxes MF3bis increased in comparison with the magnetic fluxes MF3(FIG. 27), so that a coupling coefficient in the case ofFIG. 29is restrained from being greatly decreased from the coupling coefficient in the case ofFIG. 27.

In the present embodiment, as described above, the regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5, and in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the reference position C2of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 25)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the reference position C2of the vehicle body2(and the winding axis O1) toward the one side (the arrow B side) in the reference direction CD.

With the above configuration, due to a principle similar to the principle described in Embodiment 1, even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow B side (FIG. 28), or even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow F side (FIG. 29), it is possible to restrain variations in the coupling coefficient between the power receiving coil5L and the power transmission coil8L.

Referring now toFIGS. 30 to 34, the following describes a vehicle1G and a noncontact power transmission and reception system100G in Embodiment 6.FIG. 30is a plan view illustrating a floor panel2A of the vehicle1G (a vehicle body2) in the noncontact power transmission and reception system100G, and a power reception apparatus5, a power storage apparatus6, and the like provided on a bottom surface2C side of the floor panel2A, and illustrates a state observed when the bottom surface2C of the vehicle1G is viewed from the lower side in the gravitational direction.FIG. 31is a sectional view taken along an arrow XXXI-XXXI inFIG. 30. Embodiments 5 and 6 are different from each other in the following points.

The vehicle1G of Embodiment 6 does not include the projection portion2T (Embodiment 5). A space S is provided on the arrow F side relative to a front wall5C of the power reception apparatus5and on the arrow F side relative to a front wall6C of the power storage apparatus6. A second region R2includes the space S and an exposed portion6B2, but does not include the projection portion2T (Embodiment 5) as a constituent. The space S and the exposed portion6B2constituting the second region R2is, as a whole, positioned on the other side (the arrow F side) in the reference direction CD relative to a housing5A of the power reception apparatus5, and is formed such that a magnetic permeability and an electric resistance thereof are higher than a magnetic permeability and an electric resistance of a first region R1, respectively.

Noncontact Power Transmission and Reception

In the noncontact power transmission and reception system100G, noncontact power transmission and reception is performed between the power transmission apparatus8and the power reception apparatus5of the vehicle1G.FIG. 32is a sectional view illustrating a state where the power transmission apparatus8and the power reception apparatus5of the vehicle1G perform power transmission and reception in a contactless manner in a state where the vehicle1G is aligned in the parking space9A (seeFIG. 1and so on) (in other words, a reference position C2of the vehicle1G and the winding axis O1of the power transmission coil8L accord with each other).

Aligned State

As illustrated inFIG. 32, in the present embodiment, in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the reference position C2of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 30)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the reference position C2of the vehicle body2toward the one side (the arrow B side) in the reference direction CD.

Magnetic fluxes MF1formed around the power transmission coil8L (8Lb) cross the power receiving coil5L (5Lb), similarly to Embodiment 5. Magnetic fluxes MF3formed around the power transmission coil8L (8La) pass through the space S and cross the power receiving coil5L (5La) without being affected by the projection portion2T, unlike Embodiment 5.

Positional Deviation Toward Arrow L Side

FIG. 33is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow B side only by a distance DR1, from the state illustrated inFIG. 32. Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is decreased in comparison with the case ofFIG. 32, and an amount of magnetic fluxes MF1acrossing the power receiving coil5L (5Lb) is increased in comparison with the magnetic fluxes MF1(FIG. 32). In the meantime, an amount of magnetic fluxes MF3aformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is decreased in comparison with the magnetic fluxes MF3(FIG. 32).

Positional Deviation Toward Arrow R Side

FIG. 34is a sectional view illustrating a state where the power receiving coil5L deviates from the power transmission coil8L toward the arrow F side only by a distance DR2, from the state illustrated inFIG. 32. The distance DR2is generally the same as the distance DR1(FIG. 33). The space S is placed above the power transmission coil8L (8La).

Among magnetic fluxes formed around the power transmission coil8L (8Lb), an amount of magnetic fluxes reflected by the exposed portion6B1is increased in comparison with the case ofFIG. 32, and an amount of magnetic fluxes MF1bcrossing the power receiving coil5L (5Lb) is decreased in comparison with the magnetic fluxes MF1(FIG. 32). In the meantime, an amount of magnetic fluxes MF3bformed around the power transmission coil8L (8La) and crossing the power receiving coil5L (5La) is increased in comparison with the magnetic fluxes MF3(FIG. 32).

In the present embodiment, as described above, the regions (the first region R1and the second region R2) having different magnetic permeabilities and different electric resistances are formed around the power reception apparatus5, and in a state where the power reception apparatus5and the power transmission apparatus8are aligned to each other (in a state where the reference position C2of the vehicle body2accords with the winding axis O1of the power transmission coil8L in the reference direction CD (FIG. 30)), the winding axis O2of the power receiving coil5L is placed at a position deviating from the reference position C2of the vehicle body2(and the winding axis O1) toward the one side (the arrow B side) in the reference direction CD.

With the above configuration, due to a principle similar to the principle described in Embodiment 4, even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow B side (FIG. 33), or even if the power receiving coil5L deviates from the power transmission coil8L toward the arrow F side (FIG. 34), it is possible to restrain variations in the coupling coefficient between the power receiving coil5L and the power transmission coil8L.

Embodiments have been described as above, but contents described herein are just examples in all respects and are not limitative. A technical scope of the present disclosure is shown by Claims and intended to include all modifications made within the meaning and scope equivalent to Claims.

The disclosure is industrially applicable to a vehicle capable of receiving an electric power in a contactless manner from a power transmission apparatus provided outside a vehicle body.