Patent Description:
In an electric vehicle (EV) or a plug-in hybrid vehicle (PHV), a battery for running installed thereon is electrically charged. Charging is commonly done by using a cable in the present day, but a contactless electricity supply system is also being developed. In a contactless electricity supply system, a battery is charged by electricity supplied from a power transmitter coil unit provided under ground or on the ground to a power receiving coil unit attached to a bottom of a vehicle. A patent Literature <NUM> listed below discloses a contactless electricity supply system that includes a power transmitter coil unit.

In a contactless electricity supply system, charging is done by magnetic coupling between a power transmitter coil unit and a power receiving coil unit. Here, if a foreign object exists between the power transmitter coil unit and the power receiving coil unit, specifically on the power transmitter coil unit, the charging is affected by it. Especially if the foreign object is metal, its affection to magnetic flux is noticeable, and thereby it may cause inhibition of the charging. The above-mentioned Patent Literature <NUM> also discloses an apparatus for detecting a foreign object in the contactless electricity supply system. However, even if a foreign object can be detected, charging is affected by the existence of the foreign object (a system that stops charging is also developed). Therefore, it is desired to restrict incursion of a foreign object further.

An object of the present invention is to provide a contactless electricity supply system that can restrict incursion of a foreign object and can reduce affection of incursion of a foreign object.

An aspect of the present invention provides a contactless electricity supply system that includes a power transmitter coil unit provided on a ground-side, and an elevation device for shifting the power transmitter coil unit upward from the ground. Here, the power transmitter coil unit supplies electricity to a power receiving coil unit provided on a vehicle-side by magnetic coupling with the power receiving coil unit. The power transmitter coil unit has a case that houses a power transmitter coil wound in a planar manner. A bulge is formed around a center axis of the power transmitter coil on an upper face of the case so as to bulge upward from its surrounding surface.

Note that, hereinafter with respect to the contactless electricity supply system, the term "ground-side" includes a case of "on the ground" and a case of "under the ground", and means a side paired up with the "vehicle-side". In addition, the term "ground-side" also includes a case of a "floor-side" in consideration of the system that is set up in an intermediate floor of a building. This "floor-side" also includes a case of "on the floor" and a case of "under the floor".

According to the aspect, by providing the bulge on the upper face of the power transmitter coil unit, it becomes possible to restrict incursion of a foreign object onto the bulge made one-step higher while electricity is not supplied. In addition, incursion of a foreign object onto the bulge (i.e. between the power transmitter coil unit and the power receiving coil unit) can be restricted more surely by making the bulge close to (contacted with) the bottom face of the power receiving coil unit while electricity is supplied. Further, the power transmitter coil capable of being lifted up can be made close to (contacted with) the power receiving coil unit installed in the vehicle while electricity is supplied. Therefore, a power output required for the electricity supply can be reduced, and thereby, even if a foreign object enters onto the power transmitter coil unit, affection to the power transmission due to the foreign object can be reduced.

Hereinafter, a contactless electricity supply system for a vehicle according to an embodiment will be explained with reference to the drawings. First, configurations of an entire of the system will be explained with reference to <FIG> and <FIG>.

As shown in <FIG>, the contactless electricity supply system includes an electricity supply apparatus <NUM> that is a ground-side unit, and an electricity receiving apparatus <NUM> that is a vehicle-side unit. The contactless electricity supply system supplies electricity contactlessly from the electricity supply apparatus <NUM> provided at an electricity supply station or the like to the electricity receiving apparatus <NUM> installed in a vehicle <NUM> such as an EV and a PHV to charge a battery <NUM> installed in the vehicle <NUM>.

The electricity supply apparatus <NUM> includes a power transmitter coil unit <NUM> disposed at a parking space near the charging station. On the other hand, the electricity receiving apparatus <NUM> includes a power receiving coil unit <NUM> installed on a bottom of the vehicle <NUM>. The power receiving coil unit <NUM> is disposed such that it faces to the power transmitter coil unit <NUM> when the vehicle <NUM> is parked at a predetermined position (chargeable position) in the parking space.

A power transmitter coil <NUM> (see <FIG> and <FIG>) housed in the power transmitter coil unit <NUM> is configured by a primary coil made by conductive wire(s), and supplies electricity to the power receiving coil unit <NUM>. The power transmitter coil unit <NUM> will be explained later in detail. In addition, a power receiving coil <NUM> (see <FIG>) housed in the power receiving coil unit <NUM> is similarly configured by a secondary coil made by conductive wire(s), and receives the electricity from the power transmitter coil unit <NUM>. In the present embodiment, the electricity can be supplied from the power transmitter coil unit <NUM> to the power receiving coil unit <NUM> by electromagnetic induction between the both coil units <NUM> and <NUM>.

The electricity supply apparatus <NUM> includes an electricity controller <NUM>, the power transmitter coil unit <NUM>, a wireless communication device <NUM>, a controller <NUM>, a base <NUM>, a lifting link mechanism <NUM>, a drive motor <NUM> and a distance sensor <NUM>. In the present embodiment, a lifting device for vertically lifting-up the power transmitter coil unit <NUM> from the ground is configured by the lifting link mechanism <NUM> and the drive motor <NUM>. Note that the lifting device that shifts the power transmitter coil unit <NUM> vertically above from the ground may be configured by a rotational moto and a gear mechanism, or may be configured by a hydraulic cylinder. The base <NUM> is buried under the ground, and supports the lifting device surely from beneath.

The electricity controller <NUM> converts AC power transmitted from an AC power source <NUM> to high-frequency AC power, and then supplies it to the power transmitter coil unit <NUM>. The electricity controller <NUM> includes a rectifier <NUM>, a PFC circuit <NUM>, a DC power source <NUM> and an inverter <NUM>.

The rectifier <NUM> is electrically connected with the AC power source <NUM>, and rectifies the AC power output from the AC power source <NUM>. The PFC circuit <NUM> is connected to the electrical connection between the rectifier <NUM> and the inverter <NUM>, and improves power factor by fixing up an output waveform from the rectifier <NUM>.

The inverter <NUM> is provided with a PWM control circuit configured by switching elements such as IGBT or the like, and converts DC power to AC power based on switching control signals to supply the electricity to the power transmitter coil unit <NUM>. The DC power source <NUM> outputs DC power for magnetic excitation of the power transmitter coil <NUM>.

The wireless communication device <NUM> communicates bi-directionally with a wireless communication device <NUM> provided in the vehicle <NUM>.

The controller <NUM> is a unit for integrally controlling the electricity supply apparatus <NUM>, and includes an inverter controller <NUM>, a PFC controller <NUM>, a sequence controller <NUM> and a foreign object detector <NUM>. The controller <NUM> executes a judgement process of a parking position when the vehicle <NUM> is parked at the parking space. At that time, the PFC (Power Factor Correction) controller <NUM> generates an exciting power command, and the inverter controller <NUM> controls the inverter <NUM> by generating a frequency command and a duty ratio for the exciting power. According to these, the controller <NUM> transmits the power for judging the parking position from the power transmitter coil unit <NUM> to the power receiving coil unit <NUM>.

In the judgement process of the parking position, the controller <NUM> supplies the power for judging the parking position by turning the power transmitter coil unit <NUM> into a weak excitation state (excitation weaker than that in a normal charging). In addition, the sequence controller <NUM> exchanges sequence information with the electricity receiving apparatus <NUM> via the wireless communication device <NUM>. The foreign object detector <NUM> is connected with after-explained foreign object detection coils <NUM> and <NUM> (see <FIG>) housed within the power transmitter coil unit <NUM>. The foreign object detector <NUM> detects a foreign object above the first foreign object detection coil <NUM> based on induction voltage generated in the first foreign object detection coil <NUM>, and, in addition, detects a foreign object above the second foreign object detection coil <NUM> based on induction voltage generated in the second foreign object detection coil <NUM>.

On the other hand, the electricity receiving apparatus <NUM> includes the power receiving coil unit <NUM>, the wireless communication device <NUM>, a charge controller <NUM>, a rectifier <NUM>, a relay <NUM>, a battery <NUM>, an inverter <NUM>, a motor <NUM> and a notifier <NUM>.

The charge controller <NUM> controls charging of the battery <NUM>. The charge controller <NUM> executes the judgement process of the parking position when the vehicle <NUM> is parked at the parking space. In addition, the charge controller <NUM> monitors electricity received by the power receiving coil unit <NUM>. Further, the charge controller <NUM> detects the position of the power receiving coil unit <NUM> (i.e. the position of the vehicle <NUM>) with respect to the power transmitter coil unit <NUM> based on voltage received by the power receiving coil unit <NUM> when the power transmitter coil unit <NUM> is magnetically excited.

The charge controller <NUM> also controls the wireless communication device <NUM>, the notifier <NUM>, the relay <NUM> and so on. The charge controller <NUM> sends a charging start signal to the controller <NUM> of the electricity supply apparatus <NUM> via the wireless communication device <NUM>. The rectifier <NUM> is connected with the power receiving coil unit <NUM>, and converts AC power received by the power receiving coil unit <NUM> to DC power by rectification to supply it to the battery <NUM> or the inverter <NUM> (see <FIG>).

With respect to the relay <NUM>, its on/off is switched over by the control of the charge controller <NUM>. In addition, if the relay <NUM> is switched off, the battery <NUM> and the rectifier <NUM> are electrically disconnected (see <FIG>). The battery <NUM> is an electric power source of the vehicle <NUM> that is configured by connecting plural secondary batteries.

The inverter <NUM> is provided with a PWM control circuit configured by switching elements such as IGBT or the like. The inverter <NUM> converts AC power output from the battery <NUM> to DC power based on switching control signals to supply it to the motor <NUM>.

The motor <NUM> is a three-phase AC motor, for example, and is a drive source for running the vehicle <NUM>. The notifier <NUM> is configured by a warning lamp, a display of a navigation device, a speaker or the like, and notifies various information to a user based on the control of the charge controller <NUM>.

Next, the power transmitter coil unit <NUM> will be explained more in detail with reference to <FIG>. Note that the power transmitter coil unit <NUM> includes the distance sensor <NUM> for detecting the distance to the power receiving coil unit <NUM> as shown in <FIG>, but the distance sensor <NUM> is not shown in <FIG>.

The power transmitter coil unit <NUM> houses the power transmitter coil <NUM> and the foreign object detection coils <NUM> and <NUM> within its case <NUM>. The power transmitter coil <NUM> is magnetically coupled with the power receiving coil <NUM> housed in the power receiving coil unit <NUM> to supply electricity contactlessly. The case <NUM> protects various devices provided in itself (such as the power transmitter coil <NUM> and the foreign object detection coils <NUM> and <NUM>). The case <NUM> possesses strength and rigidity enough to endure when the vehicle <NUM> runs onto it. In addition, in a case where the power transmitter coil unit <NUM> is provided in an outdoor environment, the case <NUM> also possesses enough weathering resistivity. For example, the case <NUM> is made of material, such as resin, that doesn't inhibit the above-mentioned magnetic coupling.

The power transmitter coil <NUM> is wound in a ring manner about a winding center axis O, and is wound in a planar manner so as to have an oval outline shape in the present embodiment. The winding center axis (coil axis) O is an axis that passes through a winding center and is perpendicular to a winding plane. The winding center is a median point (geometric center) of a flat figure formed by an arbitrary single winding of the power transmitter coil <NUM>. Therefore, the power transmitter coil <NUM> has the oval outline shape at whose center (i.e. around the winding center O) a hole is formed. The shape of the center hole (i.e. an inner circumferential edge 120a) of the power transmitter coil <NUM> is a rectangular shape but its four corner are rounded (see <FIG>).

The power receiving coil <NUM> is also wound in a ring manner about its winding center axis, and is wound in a planar manner so as to have an oval outline shape. The power receiving coil <NUM> also has an oval outline shape having a hole at its center (i.e. around its winding center). The power receiving coil <NUM> is smaller than the power transmitter coil <NUM>, but slightly larger than the center hole of the power transmitter coil <NUM> (see <FIG>). It is most preferable that the contactless electricity supply is done while the winding center axis of the power transmitter coil <NUM> and the winding center axis of the power receiving coil <NUM> are made completely coincident with each other.

A ferrite <NUM> is lied in a planar manner on an inner bottom face of the case <NUM>, and its whole shape is a rectangular shape larger than the power transmitter coil <NUM>. The power transmitter coil <NUM> is disposed on an upper face of the ferrite <NUM>. The power transmitter coil <NUM> is connected to the electricity controller <NUM> (the inverter <NUM>) as explained above. Note that the foreign object detection coils <NUM> and <NUM> and the ferrite <NUM> are not shown in <FIG>.

The first foreign object detection (FOD) coil <NUM> that has an oval shape at whose center a hole is formed is disposed on the power transmitter coil <NUM>. The bulge 123a and a surrounding surface 123b that is one-step lower than the bulge 123a and surrounds it are formed on the case <NUM>. The bulge 123a will be explained later more in detail. The first FOD coil <NUM> detects a foreign object on the surrounding surface 123b. The second FOD coil <NUM> having an almost rectangular shape is provided on an inward side of the first FOD coil <NUM> having the oval ring shape. In other words, the second FOD coil <NUM> is disposed beneath the bulge 123a to detect a foreign object on the bulge 123a.

The second FOD coil <NUM> is disposed higher than the first FOD coil <NUM>. A distance from the first FOD coil <NUM> to the surrounding surface 123b and a distance from the second FOD coil <NUM> to the upper face of the bulge 123a are almost identical to each other. In other words, a distance from the first FOD coil <NUM> to its detection reference plane and a distance from the second FOD coil <NUM> to its detection reference plane are made identical to each other. The first FOD coil <NUM> and the second FOD coil <NUM> are connected to the controller <NUM> (the foreign object detector <NUM>) as explained above.

As explained above, the bulge 123a is formed on the upper face of the case <NUM>. The bulge 123a is formed around the above-mentioned winding center axis O of the power transmitter coil <NUM> in a plan view (see <FIG>). An area of the center hole of the power transmitter coil <NUM> formed around the winding center axis O is an area where strong magnetic flux is generated while electricity is supplied, and incursion of a foreign object onto the power transmitter coil unit <NUM> is restricted by forming the bulge 123a. Incursion restriction of a foreign object will be explained later more in detail. The surrounding surface 123b is formed around the bulge 123a, and the surrounding surface 123b is a flat surface and is made flush with the ground surface while the power transmitter coil unit <NUM> positions at its moved-down position. The upper face of the bulge 123a is parallel to the surrounding surface 123b.

In the plan view (see <FIG>), the bulge 123a is formed around the winding center axis O of the power transmitter coil <NUM> as explained above, and the inner circumferential edge 120a of the ring-shaped power transmitter coil <NUM> is disposed on an inward side of the bulge 123a. In the present embodiment, the bulge 123a is raised upward from the surrounding surface 123b at a position just outside the inner circumferential edge 120a in the plan view. Note that the bulge 123a may be raised at a position almost coincident with the inner circumferential edge 120a as long as it includes the inner circumferential edge 120a within itself in the plan view.

Therefore, the bulge 123a also has an identical shape to that of the inner circumferential edge 120a, i.e. a rectangular shape whose four corners are rounded. Note that some sort of pattern (e.g. pattern as aesthetic design, pattern for anti-slipping or the like) may be formed on the surface of the case <NUM>, and asperity of such patterns (minute height difference) is not a "bulge". In addition, only one "bulge" is provided around the winding center axis O in the present embodiment, and it is formed such that its upper face becomes a single flat surface.

Positional relation between the bulge 123a and the above-mentioned second FOD coil <NUM> (the first FOD coil <NUM>) is shown in <FIG>. An outer circumferential edge 122a of the second FOD coil <NUM> is disposed on an inward side from a boundary inner circumferential edge 123c of the bulge 123a (on an inner face of the case <NUM>) (see an arrow in <FIG>). In the present embodiment, the outer circumferential edge 122a is made coincident with a position where the upper face of the bulge 123a shifts from a curved surface to a flat surface. <FIG> shows a cross-sectional plane (called as a reference cross-sectional plane, hereinafter), which includes an arbitrary point on the inner circumferential edge 120a, which is perpendicular to a tangential line of the inner circumferential edge 120a at the arbitrary point, and which is parallel to the above-mentioned winding center axis O. The positional relation shown in <FIG> is satisfied along an entire circumference of the bulge 123a (the inner circumferential edge 120a). By this configuration, a thickness of a boundary (circumferential edge) portion of the bulge 123a can be secured sufficiently, and degradation of strength and rigidity of the upper plate of the case <NUM> can be avoided. Especially, since stress tends to concentrate to the boundary portion of the bulge 123a, securement of strength and rigidity of this portion is important.

In addition, an inner circumferential edge portion of the first FOD coil <NUM> is positioned so as to overlap a convex side wall of the bulge 123a. According to this configuration, the first FOD coil <NUM> can cover an area that is hardly detected by the second FOD coil <NUM>. Note that the side wall of the bulge 123a may be formed as a concave side wall or a sloped plat side wall. (But, even in a case of the sloped flat side wall, within its sections where the boundary of the bulge 123a in the plan view curve, the surface of the sloped flat side wall curves along its circumferential direction.

Positional relation between the bulge 123a and (the inner circumferential edge 120a of) the power transmitter coil <NUM> is shown in <FIG>. As explained above, the bulge 123a is formed around the winding center axis O and the inner circumferential edge 120a is included within the bulge 123a in the plan view. This positional relation will be explained more in detail. <FIG> also shows the above-mentioned reference cross-sectional plane, and the positional relation shown therein is satisfied along an entire circumference of the bulge 123a (the inner circumferential edge 120a). As shown in <FIG>, defined are a boundary point (boundary line) X of the bulge 123a, a perpendicular line (perpendicular plane) Y that passes through the inner circumferential edge 120a and is perpendicular to the power transmitter coil <NUM>, and a reference oblique line (reference oblique plane) Z that passes thorough the inner circumferential edge 120a and is oblique at <NUM>° with respect to the perpendicular line Y to the outer side. Here, the boundary point X positions on the outer side from the perpendicular line Y and on the inner side from the reference oblique line Z. That is to say, the bulge 123a is disposed inside the reference oblique plane formed by the reference oblique line Z along an entire circumference of the inner circumferential edge 120a.

As explained above, an area of the center hole of the power transmitter coil <NUM> is the area where strong magnetic flux is generated while electricity is supplied, and a foreign object is restricted from entering into this area. It is known by the inventors though actual measurements (distance between the power transmitter coil <NUM> and the power receiving coil <NUM>: <NUM>) that radiated magnetic flux gets strongest at about <NUM>° with respect to the perpendicular line Y near the inner circumferential edge 120a (see an arrow in <FIG>). On an outer side from this, the magnetic flux gets weak and its directionality shifts to the lateral direction, and thereby it hardly contributes to the electricity supply. On the other hand, on an inner side from this, i.e. above the center hole of the power transmitter coil <NUM> (above the bulge 123a), the magnetic flux gets weak only slightly and its directionality is almost parallel to the perpendicular line Y, and thereby the above-mentioned strong magnetic area is formed. Therefore, it is sufficient for utilizing the strong magnetic flux to cover to <NUM>° with respect to the perpendicular line Y at a maximum. By forming the bulge 123a so as to satisfy the above conditions, the area where the strong magnetic flux is generated can be covered surely, and thereby it becomes possible to restrict incursion of a foreign object into the area effectively. Incursion of a foreign object by the bulge 123a will be explained later more in detail.

Note that, in the present embodiment, the power transmitter coil unit <NUM> is lifted up by the lifting device (the lifting link mechanism <NUM> and the drive motor <NUM>) while electricity is supplied to make the power transmitter coil unit <NUM> close to (contacted with) the power receiving coil unit <NUM>. By making the power transmitter coil unit <NUM> close to (contacted with) the power receiving coil unit <NUM>, a power output required for the electricity supply can be reduced. Therefore, even if a foreign object that cannot be detected by the FOD coils <NUM> and <NUM> and the foreign object detector <NUM> still remains on the power transmitter coil unit <NUM>, temperature rise of the foreign object (e.g. metal) due to the magnetic flux during the electricity supply can be restricted. In addition to the reduction of the required power output during the electricity supply, leakage of the magnetic flux to the environment can be also reduced, because the power transmitter coil unit <NUM> is made close to a vehicle body and the vehicle body functions as a radio shielding material.

Further, while the power transmitter coil unit <NUM> is lifted up, the distance sensor <NUM> monitors the distance to the power receiving coil unit <NUM>. Even if a foreign object that cannot be detected by the FOD coils <NUM> and <NUM> and the foreign object detector <NUM> still remains on the power transmitter coil unit <NUM>, there is possibility for enabling detection of the foreign object (e.g. a large-sized foreign object) because the approach of the power transmitter coil unit <NUM> to (contacting thereof with) the power receiving coil unit <NUM> is inhibited.

Furthermore, although a required minimum ground clearance is different for a sedan and an SUV, a design flexibility of the vehicle <NUM> can be improved in a case where the power transmitter coil unit <NUM> is lifted up so as to be optimized with the height level of the power receiving coil unit <NUM>. For example, it can be avoided that the power receiving coil unit <NUM> of an SUV have to be disposed at a lower level. And, one type of a contactless electricity supply system becomes compatible with both a sedan and an SUV. Since the vertical positional relation between the power transmitter coil unit <NUM> and the power receiving coil unit <NUM> during the electricity supply can be always made optimized, efficiency of the electricity supply can be always maintained best.

Note that monitoring of the lift-up of the power transmitter coil unit <NUM> is done not by the distance sensor <NUM>, but may be done based on an operational state of an actuator(s) of the lifting device (the drive motor <NUM> and so on). For example, if the actuator is a servomotor, the lift-up of the power transmitter coil unit <NUM> can be monitored based on the operational state of the servomotor. In addition, the electricity supply is not affected when the power transmitter coil unit <NUM> is not contacted with the power receiving coil unit <NUM> and a small clearance is formed between the two. Even with such a small clearance formed due to mechanical accuracy of the lifting device, the electricity supply can be done as long as the power transmitter coil unit <NUM> and the power receiving coil unit <NUM> are made close to each other.

The positional relation between the power transmitter coil unit <NUM> and the power receiving coil unit <NUM> during the electricity supply is shown in <FIG>. Note that only one side of the vehicle <NUM> is shown in <FIG> but the other side is also formed symmetrically. The power transmitter coil unit <NUM> is shown by its cross-sectional view in <FIG>, but the power receiving coil unit <NUM> is shown only by its outline shape. In addition, parts that are not required for the explanations are not shown in <FIG>. The power receiving coil unit <NUM> is attached to a subframe <NUM> of the vehicle <NUM>. The subframe <NUM> is also shown by being simplified. In <FIG>, the power transmitter coil unit <NUM> is lifted up, and thereby the upper face of the bulge 123a is contacted with (made close to) the bottom face of the power receiving coil unit <NUM>. The bottom face of the power receiving coil unit <NUM> is a flat surface similarly to the upper face of the bulge 123a. A suspension part <NUM> is disposed above the surrounding surface 123b.

A size of the power receiving coil unit <NUM> in the plan view in the present embodiment is identical or almost identical to a size of the bulge 123a in the plan view (i.e. the area of the above-explained strong magnetic flux effectual for the electricity supply). In the vehicle <NUM>, many parts such as the part <NUM> are disposed around the power receiving coil unit <NUM>. Here, the position of the surrounding surface 123b can be made lower by providing the bulge 123a. As the result, a clearance can be provided between the part <NUM> and the surrounding surface 123b, and thereby layout flexibility of the parts around the power receiving coil unit <NUM> can be improved.

Specifically, a height A of the bulge 123a and a protruding length B of the part <NUM> from the bottom face of the power receiving coil unit <NUM> are defined as shown in <FIG>. A>B is satisfied in the layout shown in <FIG>, and a clearance (A-B) is made between the surrounding surface 123b and the part <NUM>. In other words, the protruding length B, from the bottom face of the power receiving coil unit <NUM>, of the part <NUM> that protrudes downward from the bottom face is made smaller than the height A of the bulge 123a from the upper face of the case <NUM>. This condition is satisfied in an area of the size of the power transmitter coil unit <NUM> in a state where the power receiving coil unit <NUM> and the bulge 123a are made coincident with each other in the plan view.

Note that, if unable to approach a parking space in a straight line, it is preferable to locate the power transmitter coil unit <NUM> on a far side in the parking space in consideration of paths of wheels. According to such a location, the wheels can be prevented from passing over the power transmitter coil unit <NUM> as much as possible. In consideration of such a circumstance, the power receiving coil unit <NUM> is disposed in a front section of a vehicle under assumption of forward running parking, or the power receiving coil unit <NUM> is disposed in a rear section of a vehicle under assumption of reverse running parking. In other words, it is assumed that suspension parts are located around the power receiving coil unit <NUM>. Due to requirement of suspension geometry (especially, a position of a swing center of an arm, a beam, a rod, a link and so on), some of the suspension parts are desired to be located at a lower position. In such a case, it is very useful that the position of the surrounding surface 123b can be made lower by providing the bulge 123a.

Operations of the above-explained contactless electricity supply system will be explained with reference to a flowchart shown in <FIG>.

The charge controller <NUM> determines whether or not a user conducts a charge start operation (step S101). For example, the charge start operation is a user's operation of a charge start switch provided in a passenger compartment of the vehicle <NUM>. If the user conducts the charge start operation (Yes in the step S101), the user starts parking by running the vehicle <NUM> (step S103). Note that the parking may be started automatically by the vehicle <NUM> according to its auto parking system. On the other hand, if the user doesn't conduct the charge start operation (No in the step S101), the process flow is looped until the charge start operation is conducted.

When the parking is started in the step S103, the charge controller <NUM> starts wireless communication with the controller <NUM> via the wireless communication device <NUM> (step S105). The charge controller <NUM> sends a weak excitation request command to the controller <NUM> when the vehicle <NUM> gets close to the parking space.

The controller <NUM> detects the position of the power receiving coil unit <NUM> (step S107). The controller <NUM> supplies the electricity for the weak excitation of the power transmitter coil unit <NUM> based on the weak excitation request command that is received by it in the step S105. The charge controller <NUM> judges that the power receiving coil unit <NUM> positions within the chargeable area when electricity received by the power receiving coil unit <NUM> takes a value not smaller than a predetermined value. The controller <NUM> also confirms this judgment through the wireless communication devices <NUM> and <NUM>.

When the power receiving coil unit <NUM> positions within the chargeable area (Yes in the step S109), the controller <NUM> conducts pairing of the power transmitter coil unit <NUM> and the power receiving coil unit <NUM> (step S111). The pairing is execution of authentication for combination of the power receiving coil unit <NUM> and the power transmitter coil unit <NUM> that will supply electricity. For example, the pairing is a process for preventing an improper activation of an adjacent charging station in a parking lot in which parking stations are aligned.

When the controller <NUM> completes the pairing (Yes in the step S111), the controller <NUM> detects whether or not a foreign object exists above the power transmitter coil unit <NUM> by using the FOD coils <NUM> and <NUM> (step S115). In a case where a foreign object exists above the power transmitter coil unit <NUM> (Yes in the step S115), the notifier <NUM> notifies to the user that a foreign object exists above the power transmitter coil unit <NUM> (step S117) and then finishes the process flow. Note that, in the step S117, the notifier <NUM> may issue an instruction to remove the foreign object to the user. In this case, the process flow proceeds to a step S119 when the user has removed the foreign object.

In a case where no foreign object exists above the power transmitter coil unit <NUM> (No in the step S115), the notifier <NUM> notifies to that user that charging is available (step S119). When the user stops a running system of the vehicle <NUM> (Yes in the step S121), the process flow proceeds to a step S123 and the controller <NUM> lifts up the power transmitter coil unit <NUM> by controlling the lifting device to make it close to (contacted with) the power receiving coil unit <NUM> (step S <NUM>). Then, the controller <NUM> starts charging (step S125). When the user doesn't stop the running system (No in the step S121), the process flow is looped until the running system is stopped.

In the present embodiment, the bulge 123a is formed on the upper face of the power transmitter coil unit <NUM> that is provided on the ground-side and capable of being lifted up. Then, a foreign object is prevented from entering onto the power transmitter coil unit <NUM>, especially entering into the above-explained area where the strong magnetic flux is generated during the electricity supply, by the bulge 123a.

While no electricity is supplied, the power transmitter coil unit <NUM> is lowered down at the ground level, and thereby the surrounding surface 123b positions at the same height level as the ground. Here, the bulge 123a is at a higher level than the ground, so that it is quite unlikely that a foreign object climbs up from the surrounding surface 123b onto the bulge 123a except when it is a living object such as an insect (it is an exceptionally rare case and the living object will moves to some other place). In addition, wind may carry it onto the bulge 123a, but wind may further carry it from the bulge 123a to some other place. Furthermore, it is quite unlikely that a foreign object returns onto the bulge 123a after once dropping off from the bulge 123a to the surrounding surface 123b, and thereby a foreign object can be prevented from entering onto the bulge 123a and then remains there.

Note that, in cases explained above, there is possibilities that a foreign object enters onto the surrounding surface 123b and then remains there. However, as explained above, the power transmitter coil unit <NUM> is lifted up to be made close to (contacted with) the power receiving coil unit <NUM> in the present embodiment, so that the power output required for the electricity supply is reduced by itself. Therefore, affection to the electricity supply can be avoided sufficiently by restricting a foreign object from entering into the area of the strong magnetic flux that corresponds to the bulge 123a. Then, even if a foreign object remains on the surrounding surface 123b outside the area of the strong magnetic flux and the electricity supply is started, the electricity supply hardly affected by it. Even if it is metal, excessive temperature rise can be avoided because of the weak magnetic flux.

Especially, the first FOD coil <NUM> is provided so as to be associated with the surrounding surface 123b in the present embodiment, so that a foreign object on the surrounding surface 123b can be detected by using the first FOD coil <NUM>. Therefore, it can be avoided in the present embodiment that the electricity supply is started while a foreign object remains on the surrounding surface 123b.

Subsequently, the power transmitter coil unit <NUM> is lifted up so as to be made close to (contacted with) the power receiving coil unit <NUM> during the electricity supply. Depending on a size of a foreign object, the power transmitter coil unit <NUM> cannot be made close to (contacted with) the power receiving coil unit <NUM> when a large foreign object remains on the bulge 123a, so that existence of the object can be detected. It can be detected by the distance sensor <NUM> or through a state of the actuator of the lifting device whether or not the power transmitter coil unit <NUM> has been made close to (contacted with) the power receiving coil unit <NUM>. Especially, the second FOD coil <NUM> is provided in the present embodiment, so that a foreign object on the bulge 123a can be detected by using the second FOD coil <NUM>. A small foreign object can be detected by the second FOD coil <NUM>. Therefore, it can be also avoided in the present embodiment that the electricity supply is started while a foreign object remains on the bulge 123a.

In addition, the bulge 123a is made close to (contacted with) the power receiving coil unit <NUM> during the electricity supply. Then, the positions of the two are high from the ground, and the vehicle body functions as the shielding material. Therefore, incursion of a foreign object between the bulge 123a and the power receiving coil unit <NUM> can be prevented surely while the electricity is supplied. In the present day, charging of an EV or a PHV takes longer time than filling of gasoline. However, even if, during the long charging time, a foreign object is carried by wind or even if someone drops and scatters something near a vehicle, incursion of a foreign object between the bulge 123a and the power receiving coil unit <NUM> can be prevented surely. As the result, affection to the electricity supply can be avoided sufficiently by restricting a foreign object from entering into the area of the strong magnetic flux that corresponds to the bulge 123a.

Further, since the bulge 123a is made close to (contacted with) the power receiving coil unit <NUM> during the electricity supply, the position of the surrounding surface 123b is also high from the ground and the vehicle body functions as the shielding material. Therefore, incursion of a foreign object between the surrounding surface 123b and the vehicle body can be also prevented surely while the electricity is supplied. As the result, a foreign object can be prevented from entering onto the surrounding surface 123b, so that affection to the electricity supply can be avoided sufficiently. Note that, even if a foreign object enters onto the surrounding surface 123b, the electricity supply is hardly affected by it as explained above. In addition, the first FOD coil <NUM> is also provided in the present embodiment as explained above.

Note that the power transmitter coil <NUM> is forms to have an oval outline shape in the above embodiment, but may be formed to have a precise circular shape, an ellipsoidal shape or a multangular shape. In such a case, it is preferable that the power receiving coil <NUM> and the bulge 123a are also formed to have a shape corresponding to that of the power transmitter coil <NUM>. In addition, the second FOD coil <NUM> for detecting a foreign object on the bulge 123a is also provided in addition to the first FOD coil <NUM> in the above embodiment. However, if incursion of a foreign object onto the bulge 123a can be ensured sufficiently by forming the bulge 123a, the second FOD coil <NUM> may not be provided. Further, the lifting device vertically moves the power transmitter coil unit <NUM> in the above embodiment, but may move the power transmitter coil unit <NUM> upward in a curved manner or in an obliquely straight manner.

Furthermore, the upper face of the bulge 123a is formed as a flat surface in the above embodiment, but may be formed as a slightly curved surface or a slightly sloped surface to be slanted downward from the center of the bulge 123a such that sands and rainwaters easily drop down onto the surrounding surface 123b. Note that the contactless electricity supply system according to the present invention can be applied to an electricity supply system in which a power transmitter coil and a power receiving coil are magnetically coupled with each other, and can be applied to a resonant capacitive coupling type electricity supply system in addition to an electromagnetic inductive coupling type electricity supply system.

Claim 1:
A contactless electricity supply system for a vehicle (<NUM>), the system comprising:
- a power transmitter coil unit (<NUM>) provided on a ground-side; and
wherein:
- the power transmitter coil unit (<NUM>) includes
- a power transmitter coil (<NUM>) that is configured to supply electricity contactlessly to a power receiving coil unit (<NUM>) provided on a vehicle-side by magnetically coupling with a power receiving coil (<NUM>) housed in the power receiving coil unit (<NUM>), and
- a case (<NUM>) that houses the power transmitter coil (<NUM>),
- the power transmitter coil (<NUM>) is wound in a planar manner about a winding center axis (O),
- a bulge (123a) is formed around the winding center axis (O) on an upper face of the case (<NUM>) so as to bulge upward from a surrounding surface (123b),
- the case (<NUM>) of the power transmitter coil unit (<NUM>) also houses a first foreign object detection coil (<NUM>) and a second foreign object detection coil (<NUM>),
- the first foreign object detection coil (<NUM>) is disposed on the power transmitter coil (<NUM>) and configured to detect a foreign object above the power transmitter coil (<NUM>) based on induction voltage generated in the first foreign object detection coil (<NUM>), and
- that the second foreign object detection coil (<NUM>) is disposed beneath the bulge (123a) and configured to detect a foreign object on the bulge (123a) based on induction voltage generated in the second foreign object detection coil (<NUM>),characterized in that
- it comprises a lifting device (<NUM>, <NUM>) that lifts up the power transmitter coil unit (<NUM>) from the ground, and
- the second foreign object detection coil (<NUM>) is disposed higher than the first foreign object detection coil (<NUM>).