POWER FEEDING DEVICE

A power feeding device includes: a generator, the generator including a stator fixed to a wheel and a cylindrical rotor that rotates around a rotation axis of the wheel; an inertial member that is fixed to the cylindrical rotor and maintains a constant attitude by its own weight; a circuit board that is fixed to the stator and is mounted with a power feeding circuit to supply an output of the generator to a load; and a circuit receiving space that is provided inside the cylindrical rotor and receives a whole of the circuit board or an element that is mounted on the circuit board and protrudes from the circuit board.

TECHNICAL FIELD

The present disclosure relates to a power feeding device attached to a rotary body.

BACKGROUND ART

As this type of power feeding circuit, there is known a power feeding circuit fixed to a wheel (see, for example, Patent Document 1).

RELATED ART DOCUMENTS

Patent Document

SUMMARY OF THE INVENTION

Technical Problems to be Solved by the Invention

However, in a power feeding device attached to the rotary body as in the above-described example, the power feeding device receives a centrifugal force due to rotation; therefore, the durability of the circuit board is sometimes a problem. Therefore, the present disclosure provides a technique for improving durability of a power feeding device attached to a rotary body.

Means of Solving the Problems

The invention of claim1made to solve the above problem is a power feeding device including: a generator, the generator including a stator fixed to a wheel and a cylindrical rotor that rotates around a rotation axis of the wheel; an inertial member that is fixed to the cylindrical rotor and maintains a constant attitude by its own weight; a circuit board that is fixed to the stator and is mounted with a power feeding circuit to supply an output of the generator to a load; and a circuit receiving space that is provided inside the cylindrical rotor and receives a whole of the circuit board or an element that is mounted on the circuit board and protrudes from the circuit board.

MODE FOR CARRYING OUT THE INVENTION

First Embodiment

A power feeding device10A according to a first embodiment of the present disclosure will be described with reference toFIGS.1to4. As illustrated inFIG.1, the power feeding device10A is attached to a central part of each wheel101of a vehicle100. In order to attach the power feeding device10A, in a central part of a wheel11(corresponding to a “rotary body” of the present disclosure) of each wheel101, there is provided a circular recess14opened outward and closed on the deeper side, as illustrated inFIG.2. On an inner side of the circular recess14, there is provided a larger diameter portion14A in which the diameter of an end part on the opening side is enlarged in a stepwise manner, and in a smaller diameter portion14B on the deeper side with respect to a stepped surface14D, there is formed a locking groove14N in which locking projections26(to be described later) of the power feeding device10A are locked. The stepped surface14D is provided with a plurality of engaging recesses14K that is engaged in a concavo-convex manner with detent projections27(to be described later) of the power feeding device10A.

As illustrated inFIG.3, the power feeding device10A has a unit structure in which a generator30is attached to a housing20and a circuit board50is attached to the generator30. The housing20is, for example, made of resin and is divided into a housing main body21and a lid body22. The housing main body21is provided with a cylinder wall24having a substantially cylindrical shape, and is disposed such that a central axis thereof coincides with a rotation axis J1of the wheel11(seeFIG.2). Hereinafter, the direction parallel to the rotation axis J1in the power feeding device10A is referred to as a “front-rear direction”.

A front end opening of the cylinder wall24is closed by the lid body22, and a space between the lid body22and the cylinder wall24is waterproof-processed. An emblem22A is formed on an outer surface of the lid body22. In addition, for example, the portion where the emblem22A is formed has translucency, and the emblem22A emits light when LEDs82to be described later are turned on.

A stepped surface24D is formed at a position near the rear end of an outer surface of the cylinder wall24, and the rear side with respect to the stepped surface24D is a smaller diameter portion24S. A plurality of locking pieces25protrudes from positions slightly displaced inward from the outer surface of a rear surface of the cylinder wall24. The locking pieces25each have a structure including a locking projection26at a tip of a cantilever beam extending rearward. A plurality of detent projections27protrudes from an outer edge part of a rear surface of the housing20. The plurality of locking pieces25and the plurality of detent projections27are dispersedly arranged in the circumferential direction of the cylinder wall24, and a center of gravity of a whole of the housing20is located on the central axis of the cylinder wall24.

A support wall23having an annular shape projects inward from a position near the front end inside the cylinder wall24, and the generator30is fixed to the rear surface of the support wall23. The generator30includes a cylindrical rotor32inside a stator33having a cylindrical shape, for example. As shown inFIG.2, the cylindrical rotor32is rotatably supported, at both end parts in the axial direction, by the stator33via a pair of bearings32F.

The generator30is, for example, an AC motor, in which a plurality of magnets32J is provided on an outer surface of the cylindrical rotor32and in which a plurality of teeth33T is provided on the stator33, and an electromagnetic coil33C is wound around each of the teeth33T. In addition, a pair of ends of a winding wire33M of the electromagnetic coils33C are drawn sideward from a side surface of the stator33, and terminal metal fittings are connected to the ends and housed in a connector37C.

The generator30of the present embodiment includes a pair of output electrodes37A and37B to output an alternating current, but may instead include, for example, three output electrodes to output a three-phase alternating current.

As illustrated inFIG.3, screw holes33N are formed at respective ones of a plurality of positions in the circumferential direction at both end parts of the stator33in the axial direction. Then, screws inserted through through-holes23A formed at a plurality of positions of the support wall23in the circumferential direction are fastened to the plurality of screw holes33N in the front end of the stator33, so that the generator30is fixed to the housing20.

An inertial member40is fixed to a front end inside the cylindrical rotor32. The inertial member40has a semicircular shape, and the inertial member40is fixed to the cylindrical rotor32such that a semicircular arc surface, which is an outer surface of the inertial member40, is overlapped with a half of an inner peripheral surface of the cylindrical rotor32. As a result, a center of gravity of the combined portion of the inertial member40and the cylindrical rotor32is disposed at a position shifted from the rotation axis J1(seeFIG.2), and the cylindrical rotor32rotates relatively to the stator33in association with rotation of the wheel11. An electric power generated by the generator30by the relative rotation between the cylindrical rotor32and the stator33is output as an alternating current between the pair of output electrodes37A and37B. A part, of a cylindrical rotor32, on the rear side with respect to the inertial member40serves as a circuit receiving space39, and partially receives a plurality of elements protruding from the circuit board50to be described below.

The circuit board50is fixed to a rear end face of the stator33. The circuit board50has, for example, a disk shape that just overlaps the rear end face of the stator33. An outer edge part of the circuit board50is overlapped with the rear end face of the stator33interposing therebetween an annular spacer59having a diameter substantially the same as the outer diameter of the circuit board50, and screws inserted through a plurality of through-holes50J and59J respectively formed in the circuit board50and the spacer59are fastened to the plurality of screw holes33N at the rear end of the stator33, so that the circuit board50is fixed to the stator33.

As illustrated inFIG.4, on the circuit board50, there is provided a power feeding circuit60for applying the power generated by the generator30to a load. As illustrated inFIG.2, the power feeding circuit60includes a pair of input electrodes61A and61B in a connector50C fixed to a rear surface50B of the circuit board50. And, by coupling with the connectors37C and50C housing the output electrodes37A and37B of the generator30, the alternating current output by the generator30is supplied between the pair of input electrodes61A and61B of the power feeding circuit60. The power feeding circuit60converts the alternating current into a pulsating current by a diode circuit63, smooths the pulsating current by a smoothing circuit64, and outputs the smoothed current between a pair of output electrodes62A and62B. That is, the power feeding circuit60of the present embodiment is a rectifier circuit that rectifies the alternating current output by the generator30.

As illustrated in, for example,FIG.4, the diode circuit63is a general bridge circuit having, for example, four diodes63A. The smoothing circuit64is configured with a smoothing capacitor64A parallel-connected between the pair of output electrodes62A and62B of the power feeding circuit60. In addition, a resistor65as a current reducing element is connected between the smoothing circuit64and one output electrode62A. As shown inFIG.3, the plurality of elements included in the power feeding circuit60is mounted on a front surface50A of the circuit board50, protrudes forward, and is received in the circuit receiving space39of the cylindrical rotor32. More specifically, among the elements included in the power feeding circuit60, the smoothing capacitor64A of the smoothing circuit64having the largest mass is disposed at the center of the circuit board50, and the plurality of diodes63A included in the diode circuit63and the resistor65are dispersedly disposed around the smoothing capacitor64A, so that the center of gravity of the entire circuit board50is disposed at a central part of rotation.

As shown inFIG.2, an electric decoration board89is attached on the front side of the circuit board50via a plurality of support posts, and housed in the circuit receiving space39. An electric decoration circuit80illustrated inFIG.4is mounted, as a load, on the electric decoration board89, and is connected to the pair of output electrodes62A and62B of the power feeding circuit60of the circuit board50. Specifically, the electric decoration board89has a disk shape, and is disposed such that the center of the electric decoration board89coincides with the rotation axis J1. The electric decoration circuit80includes: a plurality of LEDs82for electric decoration; a control circuit83that controls lighting of the LEDs; a secondary battery84that is a power source for the LEDs and the control circuit83; and a charging circuit85for charging the secondary battery84(seeFIG.4). In addition, the control circuit83includes a wireless circuit (not illustrated) to receive a turn-on command and turn-off command by a wireless signal from a main body side of the vehicle100, and the LEDs82are turned on or off according to the command. Furthermore, the output electrodes62A and62B of the power feeding circuit60are connected to the charging circuit85through a cable (not illustrated) or the like, and the secondary battery84is charged when a remaining capacity of the secondary battery84is low. The elements mounted on the electric decoration board89are also disposed such that the center of gravity of the whole electric decoration board89is located at the central part of rotation.

The housing20is fixed to the wheel11in the following manner. Specifically, the plurality of detent projections27of the housing20and the plurality of engaging recesses14K (seeFIG.2) of the wheel11are opposed to each other, and the housing20is then pushed into the circular recess14of the wheel11from the side of the plurality of locking pieces25. Then, the plurality of locking pieces25is bent so as to shrink inward, so that the plurality of detent projections27is engaged in a concavo-convex manner with the plurality of engaging recesses14K. Then, when the stepped surface24D of the housing20comes into contact with the stepped surface14D of the circular recess14, the plurality of locking pieces25elastically returns, and the locking projections26get engaged with the locking groove14N of the wheel11. As a result, the housing20is integrally rotatably fixed to the wheel11. In addition, a sealing material is applied between an inner surface of the cylinder wall24of the housing20and an inner surface of the circular recess14, and a space, of the circular recess14, on the deeper side with respect to the stepped surface14D is sealed to be in a waterproof state and becomes a waterproof space.

The configuration of the power feeding device10A of the present embodiment has been described above. The power feeding device10A is stopped and does not generate power while the vehicle100is stopped. However, as a diode85A that is included in the charging circuit85of the electric decoration circuit80, which is a load, is included, power is not supplied from the secondary battery84of the electric decoration circuit80to the power feeding device10A.

When the vehicle100travels, the stator33of the generator30fixed to the wheel11of the wheel101rotates with respect to a road surface together with the wheel11; however, the inertial member40's own weight restricts rotation of the cylindrical rotor32of the generator30with respect to the road surface, and the cylindrical rotor32therefore rotates relatively to the stator33. As described above, in the power feeding device10A of the present embodiment, the rotation of the wheel11and an inertia of the inertial member40are used to rotate the cylindrical rotor32relatively to the stator33of the generator30, thereby generating power, and the power can be supplied to the electric decoration circuit80. In the generator30, the elements mounted on the circuit board50are received in the circuit receiving space39inside the cylindrical rotor32, the plurality of elements can therefore be gathered in the vicinity of the center of the rotation axis J1, and a centrifugal force applied to the circuit board50is accordingly reduced; therefore, durability of the power feeding device10A is improved, and, at the same time, the generator30and the power feeding device10A are made compact in the axial direction of the rotation axis J1. In addition, the electric decoration board89on which the electric decoration circuit80serving as an electric load of the power feeding device10A is mounted is also housed in the circuit receiving space39; therefore, the entire power feeding device10A including the load is also made compact in this respect. In addition, in the circuit board50and the electric decoration board89, the plurality of elements is disposed such that the center of gravity of the whole of the circuit board and the electric decoration board is disposed at the center of rotation. Therefore, this also improves the durability of the power feeding device10A.

Second Embodiment

A power feeding device10B of the present embodiment is illustrated inFIG.5. In the power feeding device10B, the inertial member40is disposed in a rear part of a cylindrical rotor32V, and the front side with respect to the inertial member40of the cylindrical rotor32V is the circuit receiving space39. An inner diameter of a support wall23V of a housing20V is smaller than an inner diameter of the cylindrical rotor32V, and a board housing wall23X having a cylindrical shape extends rearward from an inner edge part of the support wall23V and is received in the circuit receiving space39. Furthermore, a rear end of the board housing wall23X is closed by a rear end wall23Y. The circuit board50and the electric decoration board89described in the first embodiment are housed in the board housing wall23X, and the circuit board50is fixed to the rear end wall23Y. A winding wire33M of a generator30V passes through an electric wire insertion hole23E formed in the support wall23V, is taken into the board housing wall23X from the front, and is connected to the power feeding circuit60of the circuit board50. The configuration of the present embodiment also achieves the same actions and effects as the first embodiment.

OTHER EMBODIMENTS

(1) The generators30and30V of the first and second embodiments may have the same structure as a brushed DC motor. In this case, a direct current is output from the generator30or30V; therefore, the power feeding circuit60only has to include an electric path for relaying between the pair of output electrodes37A and37B of the generators30or30V and the electric decoration circuit80, or only has to include a voltage dividing circuit for adjusting a voltage to be applied to the electric decoration circuit80.

(2) In the first and second embodiments, the load that receives power from the power feeding device10A or10B is the electric decoration circuit80, but the load is not limited thereto, and may be a tire monitoring device for monitoring a state of a tire mounted on the wheel11.

(3) In the power feeding devices10A and10B of the first and second embodiments, the load includes the secondary battery84, and the power feeding devices10A and10B do not include a secondary battery. However, the power feeding devices10A and10B themselves may include a secondary battery. In that case, power can be supplied from the power feeding device10A to the load also when the vehicle100is stopped.

(4) Furthermore, the inertial member40is not limited to the above shape, and may have any shape and any material as long as the inertial member has a center of gravity at a position shifted from the rotation axis J1, and does not have to be disposed inside the cylindrical rotor32.

Although the present specification and the drawings disclose specific examples of the techniques included in the claims, the techniques according to the claims are not limited to these specific examples, and include various variations and modifications of the specific examples and, in addition, include a part alone taken out from the specific examples.

DESCRIPTION OF THE REFERENCE NUMERAL