GB2271516A

GB2271516A - An electromotive car for infants.

Info

Publication number: GB2271516A
Application number: GB9320878A
Authority: GB
Inventors: Myung Soon Bae
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-13
Filing date: 1993-10-11
Publication date: 1994-04-20
Also published as: GB9320878D0; CA2106838A1; FR2696651A1; JPH06134144A; DE4334764A1; CN1085852A

Abstract

A car includes pairs of front and rear wheels 34 and 36, a seat 12, an electric drive motor 54 to propel the car, a drive unit 52 adapted to drive the car and to turn the car automatically when the load of the motor is increased due to an obstacle. The car further includes a control circuit (110 fig 7) for controlling the speed of the car, producing various melodies and to detect an overcharge and overdischarge of a battery (108 fig 6). Preferably, the car is provided with a steering unit 26 which comprises a steering wheel 28, a shaft 30 having a spring receptacle 46 in which a spring 40 is contained, first and second driven gears 42 and 44 cooperated with the shaft 30. In the drive unit 52, a gear 74 is provided at an upper periphery of a housing 66 and engaged with the second driven gear 44. The housing 66 can be turned due to the increased load of the motor 54 so that the car can avoid obstacles in the running direction thereof. Drive is transferred from the motor to the wheels 72 via bevel gears 62, 64. The axle 70 upon which the wheels 72 and bevel gear 64 are mounted passes through holes (68 fig 4) in the housing 66. The car may employ a sensor to detect obstacles which may then be avoided. <IMAGE>

Description

ELECTROMOTIVE CAR FOR INFANTS The present invention relates to an electromotive car for infants, more particularly, to an electromotive car which runs by a driving unit operated with an electric motor and which is automatically turned upon the contact of a car body with an obstacle.

Recently, many kinds of toy cars which run manually or automatically have been proposed. In such a manually operable car, front wheels and rear wheels are mounted on respective ends of forward and rearward shafts disposed on a bottom plate of the car. A steering unit is adapted to turn the car body, and a drive means such as a pedal serves to operate the car.

With such a construction of manually operated car, as the drive unit is manually operated by an infant while a direction of the car is turned by way of the steerable wheels, the car can be forwardly advanced. In fact, it is necessary to operate the drive means by the infant's feet in order to drive the car along. This causes the speed of the car to be limited whereby the infant feels a repugnance to the car . Also, in case of an increase in size of the car, it is difficult to drive the car in a limited space, for example, a room, a drawing room or the like. Furthermore with the car having to be propelled by the infant's feet, a small child cannot operate the car because substantial power is needed to drive the car along.

Alternatively, an automatically propelled car has an electric motor for driving the wheels, which is powered by a battery. That is, the automatic car is constructed such that the car automatically runs by way of the electric motor while being turned in direction by means of the steering wheel.

With the automatic car constructed as described above, however, when the infant on the car operates the steering wheel unskilfully, the car cannot be turned correctly to avoid a collision with obstacles. Due to the construction of the car, when it is in an obstructed stationary state, it is not turned in direction even if the steering wheel is manipulated. When such a car is in collision with an obstacle a driver has to get out from the car and manhandle it in order to move it out of contact with the obstacle, thereby resulting in a disadvantage in use of the car.Furthermore, when the car is distributed by the obstacles and is automatically turned in direction, the electric motor serving as the driving source is overloaded whereby not only components such as the electric motor are damaged due to the overload affected on the car but also the power consumption of the battery supplying the operating voltage to the car is increased undesirably, thereby reducing the lifetime of the battery.

A cradle as a means to soothe a crying child, has been proposed. Such a cradle has a construction wherein it is suspended from a ground at a constant height by way of a rope and etc and supported by curved support members attached at respective lower sides thereof. With the construction, the cradle on which a baby or an infant is taken must be artificially vibrated by guardian. As a result, a disadvantage is caused in that an assistant is necessary for driving the cradle.

The present invention seeks to provide an improved electromotive car for infants, in which an electric motor driven under a control of a control unit is employed to automatically run the car along a desired direction set by a steering unit and which can avoid obstacles located in a running direction thereof even if a main body of the car is contacted with the obstacle.

A refinement of the present invention may provide an electromotive car for infants, which is embodied as a cradle and automatically turns in a running direction upon the contact of the car body with obstacles.

Further refinements of the present invention may provide an electromotive car having an electric control unit which controls the speed of an electric motor serving as a drive source and/or checks a load acted on the motor for driving the car and/or produces various melodies confirming the car running state and/or prevents the overcharge and overdischarge of a rechargeable battery for supplying the operating voltage to the car.

According to one aspect of the invention there is provided an electromotive car for infants comprising driving wheels mounted on the car body which can be swivelled automatically relative to the direction of travel of the car upon detection of an obstruction so as to change the direction of travel to avoid the obstruction.

According to another aspect of the invention there is provided an electromotive car for infants, comprising a car body having a pair of front wheels and rear wheels attached at a front and rear side of a bottom plate thereof, the wheels being arbitrarily driven in running the car, the front wheels being in a non-contact relation with the ground and the rear wheel being in a contact relation with the ground, a driving seat, a steering means having a steering wheel for changing the car running direction and steering force transmission means for receiving the steering force produced by the steering wheel, the steering wheel being disposed in front of the driving seat, an electromotive drive means built in the car body for producing a driving force required to run the car, a drive means for running the car along the direction steered by the steering wheel and for automatically changing the car running direction upon increased load on the drive means, a rechargeable power supply means for supplying the operating voltage to the car, and a control means for producing various melodies during running of the car, varying the speed of the electric drive means and determining the overcharge and overdischarge of the power supply means.

The steering means may include a steering shaft integrally connected to the steering wheel, a steering force transmission member connected to the steering shaft for transferring the steering force from the steering wheel to the drive means, a first driven gear fixedly engaged to a lower end of the steering shaft and a second driven gear for transferring the steering force from the steering wheel to the drive means, and transferring the driving force from the driving means to the steering wheel.

The drive means may comprise a large gear engaged with a small gear mounted on a driving shaft of the electric drive motor for transferring the driving force from the drive means, the large gear being a helical gear and the small gear being a worm gear, a horizontal and a vertical bevel gear engaged in a mutually intersecting direction and rotated by way of a shaft fixedly attached to the large gear, a pair of steerable wheels mounted at respective ends of a propulsion axle and driven by the bevel gears, the propulsion axle being fixedly fitted through a centre of the vertical bevel gear, and a housing having a shaft insertion aperture formed at the centre of an upper projection thereof, a threaded gear defined on a periphery of the upper projection and a propulsion axle insertion aperture formed at a predetermined position on a lower side thereof, the gear on the periphery being engaged with the second driven gear of the steering means and the bevel gears being accommodated in the housing, wherein the housing is rotated by the load of the steerable wheels increased when the car is affected by an obstacle.

The driving seat may comprise a seat for the driver, a footrest at a forward side of the seat, divided by a partition, and a seat back formed at the back of the seat.

The control means may comprise an oscillator for generating a cyclic charging signal for said power supply means, an overcharge preventing circuit for detecting an overcharged state of the power supply means, a charging state detector for checking a charging operation state of the power supply means, a speed controller for setting the speed of the electric drive means, a microprocessor for producing various melody sounds whilst running the car and outputting a control signal to drive the electric drive means, a drive means for driving the electric drive means under control of the microprocessor, and an overdischarge detector for detecting an overdischarged state of the power supply means.

According to another aspect of the present invention, there is provided an electromotive car in the form of a cradle, comprising a car body having a pair of front wheels and rear wheels attached at a front and rear side of a bottom plate thereof, the wheels being arbitrarily driven in running the car, the front wheels being in a noncontact relation with the ground and said rear wheels being in a contact relation with the ground, a bed having a seat back, an electric drive means built in the car body for producing a driving force required to run the car, a drive means for running the car along the direction steered by the steering wheel and for automatically changing the car running direction upon increasing on the drive means, a rechargeable power supply means for supplying the operating voltage to the car; and, a control means for producing various melodies during running of the car, varying the speed of the electric drive means and determining the overcharge and overdischarge of the power supply means.

The drive means may comprise a large gear engaged with a small gear mounted on a driving shaft of the electric drive motor for transferring the driving force from the drive means, the large gear being a helical gear and the small gear being a worm gear, a horizontal and a vertical bevel gear engaged in a mutually intersecting direction and rotated by way of a shaft fixedly attached to the large gear, a pair of steerable wheels mounted at respective ends of a propulsion axle and driven by the bevel gears, the propulsion axle being fixedly fitted through a centre of the vertical bevel gear, and a housing having a shaft insertion aperture formed at the centre of an upper projection thereof, a threaded gear defined on a periphery of the upper projection and a propulsion axle insertion aperture formed at a predetermined position on a lower side thereof, the gear on the periphery being engaged with the second driven gear of said steering means and the bevel gears being accommodated in the housing, wherein the housing is rotated by the load of the steerable wheels increased when the car is affected by an obstacle.

The control means may comprise an oscillator for generating a cyclic charging signal for said power supply means, an overcharge preventing circuit for detecting an overcharged state of said power supply means, a charging state detector for checking a charging operation state of the power supply means, a speed controller for setting the speed of the electric drive means, a microprocessor for producing various melody sounds whilst running the car and outputting a control signal to drive the electric drive means, a drive means for driving the electric drive means under control of the microprocessor, and an overdischarge detector for detecting an overdischarged state of the power supply means.

In a refined form of the present invention, the electromotive car runs by an electric drive motor serving as the electric drive means with a melody being produced under a control of a microprocessor. When the car is affected by any obstacles placed on the car running direction and a torque is overly applied to a joint of the horizontal and vertical bevel gears, the housing including the steerable wheels is rotated to a direction where the torque is reduced.

In order that the invention and its various other preferred features may be understood more easily, some embodiments thereof will now be described, by way of example only, with reference to the drawings in which, Figure 1 is a perspective view showing schematically the possible appearance of an electromotive car for infants constructed in accordance with the present invention, Figure 2 is a side cross-section view of the car shown in Figure 1, Figure 3 is an exploded perspective view illustrating a steering unit shown in Figure 2, Figure 4 is an exploded perspective view illustrating a drive unit shewn in Figure 2, Figure 5 is an enlarged cross-section view of a main part of a joint of the steering unit and the drive unit shown in Figures 3 and 4, Figure 6 is a block diagram of an electric circuit for a car constructed in accordance with the invention, Figure 7 is a detailed circuit diagram of a control circuit shown in Figure 6, Figure 8 is a perspective view showing schematically the appearance of an electromotive car of cradle type for infants also constructed in accordance with the invention, Figure 9 is a schematic view showing a modified version of the car shown in Figure 8, and Figure 10 is a schematic side view of a drive unit of the embodiment shown in Figure 8.

Referring to Figure 1, reference numeral 10 denotes a body of the electromotive car. The car body 10 has a driving seat 12 defined at a rear of the upper side thereof.

The driving seat 12 includes a seat 14 on which a driver or infant gets to drive a steering wheel, as will be described later. At a front side of the seat 14, a footrest 16 having a constant depth from the upper level of the seat 14 is divided by a partition 18, and a seat back 20 is formed at the rear of the seat 14. On a panel forward of the seat 14 are disposed a power switch 22 and a speed controller switch 24 for adjusting the speed of an electric drive motor serving as an electric drive means. A steering wheel 28 is mounted on the panel to steer the car body 10. At a lower periphery of the car body 10, a shock absorber member 32 made of, for example, rubber is provided so as to absorb a shock transferred to the car 10 upon colliding with obstacles and to prevent the car from being damaged.

Referring to Figure 2, a side cross-sectional view of the electromotive car shown in Figure 1 is illustrated.

At the front and rear of the car body 10, a pair of front wheels 34 are arranged in a non-contact relation with the ground and a pair of rear wheels 36 are arranged in a contact relation with the ground, respectively. These wheels 34 and 36 are arbitrarily driven to assist the car body 10 when the latter runs in the direction steered by the steering wheel 28. The car body 10 is provided with a frame 38 which divides the inner space of the car body 10, which is defined between the front wheels 34 and the rear wheels 36.

At an upper side of the frame 38, a steering unit 26 is disposed to change the direction of the car body 10. The steering unit 26 includes the steering wheel 28 which is manually operated by the driver to steer the car body 10, a steering shaft 30 which cooperates with the steering wheel 28, a steering force transmission member 40 which receives a steering force from the steering shaft 30 and transfers the force toward a drive unit 52 which will be described later, and first and second driven gears 42 and 43.

The drive unit 52 is connected to the steering unit 26 via the driven gears 42 and 44. The drive unit 52 is operated by a driving force from an electric drive motor 54 to drive the car body 10 in the direction set by the steering unit 26 and to automatically change the car running direction when the car body 10 contacts an obstacle. The drive unit 52 has a large gear 58 such as a helical gear, which receives the driving force from the electric drive motor 54, a horizontal bevel gear 62 which is secured to a shaft 60 serving as a central axis of the large gear 58 and a vertical bevel gear 64 engaged with the horizontal bevel gear 62. The horizontal and vertical bevel gears 62 and 64 are accommodated in a housing 66 which can be rotated around the shaft 60 when the car body 10 is affected by a load increased by the obstacle.A pair of steerable wheels 72 are attached to a central axis of the vertical bevel gear 64, that is, both ends of an axle 70 extended through axle insertion openings 68 formed in opposed sides of the housing 66.

Figures 3 and 4 show exploded perspective views illustrating main parts of the steering unit 26 and the driving unit 52, respectively and Figure 5 is an enlarged cross-section view showing the steering unit 26 and the driving unit 28 associated therewith. More specifically, the steering wheel 28 of the steering unit 26 extends upwardly of the car body 10 so that the driver handles the steering wheel 28 to steer the car body 10. The steering wheel 28 is provided integrally with the steering wheel 30 which transfers the steering force applied to the steering wheel 28 to a side of the driving unit 52.

As shown in Figures 3 to 5, the steering shaft 30 comprises an upper steering shaft 30a and a lower steering shaft 30b which are mutually coupled through a spring 40 serving as a steering force transmission member inserted therebetween. In other words, each of spring receptacles 46 are formed at a lower end of the upper steering shaft 30a and an upper end of the lower steering shaft 30b, respectively. At a central portion of the respective spring receptacles 46, spring fixing projection 48 having a spring fixing groove 50 is defined such that respective ends of the spring 40 are inserted in the corresponding spring fixing groove 48 to transmit the steering force of the steering wheel 28 toward the driving unit 52. Further, the lower steering shaft 30b is engaged at its lower end with the first driven gear 42 which is engaged with the second driven gear 44.This second driven gear 44 is engaged with a toothed gear 74 of an upper periphery of the housing 66 in the driving unit 52 so that the steering force from the steering shaft 30 is transferred toward the driving unit 52 or contrarily.

In the drive unit 52, the shaft 60 extends vertically through the frame 38. On the upper end of the shaft 60, the large gear 58, comprising a helical gear is mounted, while on the lower end of the shaft 60, the vertical bevel gear 62 engaged with the horizontal bevel gear 64 is secured. The large gear 58 is engaged with a small gear 56 comprising a worm gear which transfers the driving force of the electric motor 54 to drive unit 52.

The horizontal and vertical bevel gears 64 and 62 are accommodated in the housing 66 having an inner space in which the gears 62 and 64 can be rotated. The housing 66 also has the toothed gear 74 on the upper periphery thereof.

A shaft insertion aperture 76 through which the shaft 60 is inserted is formed at an upper centre of the housing 66.

Moreover, axle insertion apertures 68 are opened at opposite sides of the bottom of the housing 66 and fixedly inserted with the axle 70 extended through the centre of the vertical bevel gear 64. That is, the ends of the axle 70 are outwardly extended to an exterior of the housing 66 through the axle insertion aperture 68 where the steerable wheels 72 are mounted. Furthermore, a bearing 78 is disposed in the shaft insertion aperture 76 to assure a smooth rotation of the shaft 60 and a projecting support 80 is formed at a centre of the shaft 60 to prevent the shaft from being removed.

Figure 6 is a schematic block diagram of an electrical circuit of the car. In the drawing, a plug 100 for connection to a socket of a commercial AC power supply is connected to a charged 102; for charging a rechargeable battery 108 serving as the power supply source for the car, and an output side 104 of the charger 102 is connected via a jack 106 to the battery 108. Furthermore, the power switch 22 of Figure 1 is connected to the battery 108 and a control unit 110 which controls the speed of the motor 54 and produces various melodies. The control unit 110 is adapted to control the overcharge and overdischarge of the battery 108. A speaker SP e.g. piezo electric speaker, is connected to the control unit 110.With the electrical arrangement shown in Figure 6, the plug 100 is connected to the AC power supply and the output 104 of the charger 102 connected to the plug 100 is connected to the jack 106 of the battery 108, so as to charge the battery 108. When the power switch 22 is closed, the motor 54 is driven and, simultaneously, the melodies are sequentially reproduced through the speaker SP, under the control of the control circuit 110.

Referring to Figure 7, a detailed circuit diagram of the control unit 110 is illustrated. In the drawing, an emitter of a PNP transistor Q1 is connected to the jack 106 for charging the battery 108 in a cyclic charging manner.

The transistor Q1 is connected at its collector to the rechargeable battery 108 and connected at its base to an overcharge preventing circuit 114 for preventing the battery 108 from being overly charged. The base of the transistor Q1 is also connected to an oscillator 116 which switchingly drives the transistor Q1 to effect the cyclic charging for the battery 108.

The overcharge preventing circuit 114 is composed of series-connected resistors R1 and R2 for detecting an overcharge level of the battery 108, an inverter IV1 having an input connected to a mode between the resistors R1 and R2 and a diode D1 which is reversely connected to the inverter IV1. The oscillator 116 includes inverting amplifiers IV2 and IV3 serially connected to the diode D1 of the overcharge preventing circuit 114, time constant elements R4 and C1 parallely connected to the inverting amplifiers IV2 and IV3 and a switching transistor Q2 having a base connected to the output of the inverting amplifier IV3 through a resistor R5 and a collector connected to a base of the transistor Q1 via a resistor R6.

A voltage regulator circuit 118 which includes a voltage regulator VC1 and a smoothing capacitor C2 is connected to the battery 108 via a power switch 22 so as to regulate the power voltage output of the battery 108 into an operating voltage Vcc (+5V) required to drive the car.

Furthermore, an overdischarge detecting circuit 120 is connected to the battery 108 for detecting a dropped voltage level of the battery 108. The overdischarge detecting circuit 120 has overdischarge level setting resistors R7 and R8, two inverting amplifiers IV4 and IV5 which are serially connected to a mode between the resistors R7 and R8 and a resistor R9. The inverting amplifiers serve as buffers.

A charging detector 122 which includes serially connected resistors R10 and R11 for detecting an input of a charging voltage in a battery charging mode is connected to the jack 26.

A one-chip microprocessor 124 has a plurality of input/output ports PAO to PA3 for receiving various input signals and outputting control signals. More specifically, the port PA2 of the microprocessor 124 receives a charging detect signal from the charging detector 122 to thereby inhibit the movement of the car body 10 during the battery charging mode. The port PA3 of the microprocessor 124 is connected to the output of the overcharge detecting portion 120 and the port PAO thereof is connected to a motor speed setting circuit 126 which comprises a variable resistor VR1 associated with the speed control switch 24 in Figure 1, a resistor R12 and a capacitor C3.The motor speed setting portion 126 functions to provide a charging time of the capacitor C3 varied by the variable resistor VR1 with respect to a reference value (a threshold value) previously set within a range of the charging voltage of the capacitor C3 as a motor speed signal which, in turn, is applied to the microprocessor 124.

Moreover, the microprocessor 124 has a plurality of output ports PBO through PB7 which are connected to corresponding one of the resistors R13 through R20 comprising a digital to analog converter 128 that converts the melodies or alarm signal from the microprocessor 124 in to a voltage level. In the digital to analog converter 128, resistance of the respective resistors R13 through R20 are preferably set in such a way that the resistance from a maximum value to a minimum value is to be twice. The digital to analog converter 128 is connected with a base of a transistor Q3 through a capacitor C5 and a resistor R21, and a speaker SP is connected to a collector of the transistor Q3.

A motor driver 130 is coupled with the port PA2 of the microprocessor 124 for driving the motor 54 on the basis of the speed set by the motor speed setting portion 126. The motor driver 130 includes a transistor having a base connected to the port PA2 of the microprocessor 124 through a resistor R23, a transistor Q5 having a base connected to a collector of the transistor Q4 via a resistor R24 and a collector connected to one end of the motor 54, a transistor Q6 having a base connected to the other end of the motor 54 and a collector receiving the power voltage Vce through a resistor R25, and a transistor Q7 having a base connected to the collector of the transistor Q6 via a resistor R27. The transistor Q7 is turned ON/OFF by a control signal output from the port PA1 of the microprocessor 124 and serves to mute the melody output from the microprocessor 124.At a connection point of the motor 54 to the base of the transistor Q6, a resistor R26 is arranged so as to detect an overload acting on the motor 54.

Diodes D4 and D5 for removing a serge voltage are parallely connected between the motor 54 and the transistor Q4.

Now, an operation of the control circuit 110 thus constructed will be described in detail.

In a case of the mode of charging the battery 108, when the output 104 of the charger 102 is joined to the jack 106, an inverse current protecting switch 112 is opened.

Substantially, at an initial timing of charging the battery 108 the over-charging level set by the resistors R1 and R2 of the over-charge preventing circuit 114 is a low level and, thus, the inverter IV1 outputs a high level. Under this condition, the oscillator 116 outputs a signal depending upon a time constant defined by the resistor R4 and the capacitor C1 and the transistor Q2 is switchingly turned ON/OFF in accordance with the signal supplied from the oscillator 116. Then, the transistor Q1 is also switchingly turned ON/OFF according to the switching ON/OFF of the transistor Q2 so that the battery 108 can be charged with a DC voltage in the cyclic charging manner with a result of an expanded lifetime and improved charging efficiency of the battery 108. At this time, the microprocessor 108 receives the signal representing the battery charging mode from the resistors R10 and R11 and inhibits the movement of the car during the battering charging mode.

If the charged level of the battery 108 exceeds the value defined by the resistors R1 and R2 of the overcharge preventing portion 114, the output of the inverter IV1 becomes a low level. Accordingly, the diode D1 is rendered conductive and the oscillator 116 is thus stopped, thereby completing the battery charging mode.

After the battery charging mode has been completed, the charged voltage of the battery 108 is gradually discharged by turning ON the power switch 22 and the voltage is supplied to the voltage regulator 118 through the power switch 22 and the diode D2. The voltage regulator 118 converts the voltage discharged from the battery 108 into a voltage level required to operate the respective circuit components.

Subsequently, when the microprocessor 124 detects a non-connection of the charger 102 to the battery 108, that is, the completion of the battery charging mode on the basis of the signal supplied from the resistors R10 and R11, it determines the charging threshold level Vth of the capacitor C3 with respect to the time constant adjusted by the variable resistor VR1 of the motor speed setting circuit 126 so as to read the set speed of the motor 54. In other words, if the charging time of the capacitor C3 to the charging threshold level is relatively prolonged, then the microprocessor 124 determines that the speed of the motor 54 is high in speed. On the other hand, if the charging time of the capacitor C3 is shorter, then the microprocessor 124 determines that the motor 54 is low in speed.

Next, the microprocessor 124 sequentially outputs the previously programmed melodies through the digital to analog converter 128 to the transistor Q3 which in turn drives the speaker SP for reproducing the melody. At this time, the microprocessor 124 produces a PWM motor driving signal through the port PA2 to the transistor Q4 which, in turn, is turned ON to drive the transistor Q5, thereby running the motor 54. Accordingly, the car can be driven by the motor 54.

At this condition, if the motor 54 is overloaded by collision of the car with obstacles, current through the resistor R26 and the voltage across it, is increased (i.e., V = I x R) and the transistor Q6 is thus turned OFF.

Accordingly, the potential of the port PA1 of the microprocessor 124 becomes a high level. The microprocessor 124, therefore, determines the overload acting on the motor 54 and, then, sets the output of the port PA2 to a low level. In this case, the transistor Q4 is turned OFF and the motor 54 is thus stopped.

Under the stoppage of the motor 54, the microprocessor 54 intermittently outputs the motor driving signal through the port PA2 to check the level of the current across the resistor R26 so as to determine the disappearance of the over-load acting on the motor 54. As a result, when the motor 54 is operated under a rated load thereof, the transistor Q6 is turned ON and subsequently, the microprocessor 124 outputs the melody signal through the output terminals PBO to PB7.

Meanwhile, if the voltage of the battery 108 is dropped lower than a predetermined level which is referred to the overdischarged state of the battery 108, then the output of the buffer comprising the inverters IV4 and IV5 becomes a low level which, in turn, is input to the port PA3 of the microprocessor 124. Accordingly, the microprocessor 124 produces an alarm representing the overdischarge state of the battery 108 through the output terminals PBO to PB7 instead of the output of the melody. The alarm signal can be sounded even if a melody off switch 40 is opened.

Alternatively, if the melody off switch 40 is closed, the microprocessor 124 supplies the high level signal to the transistor Q7 through the port PA1 so as to mute the melody.

Under such overdischarge state, when the DC charger 102 is connected to the battery 108 (see Figure 6), the cyclic charging mode is effected for the battery 108 as is described above and, simultaneously, the battery charging voltage level detected by the resistors R10 and R11 is input to the port PA2 of the microprocessor 124. Then, the microprocessor 124 inhibits the output of the ports PAO, PA1, PA2 and PA3 to stop the movement of the car.

The operation of the car will now be described. When the driver such as an infant sits in the seat 12 and operates the power switch 22, the melody is sounded under the control of the microprocessor 124 and the motor driver 130 drives the motor 54 on the basis of the speed properly set by the motor speed setting portion 126. Thus, the small gear 56 coupled to the motor 54 is driven to rotate the large gear 58 such as a helical gear. By rotating the large gear 58, the shaft 60 is also rotated and the horizontal bevel gear 62, so that the vertical bevel gear 64 intersecting the horizontal bevel gear 62 operates the wheel shaft 70 to be rotated. Accordingly, the steerable wheels 72 are turned to thereby advance the car.

In running, if the car collides with an obstacle such as a doorsill or furniture, a torque is acted on the joint between the horizontal and vertical bevel gears 62 and 64 in the housing 66 such that the housing 66 including the steerable wheel 72 is rotated in a torque direction and the direction of running the car is changed.

Assuming that the car is not turned in direction due to the obstacles and the load acting on the motor 54 is increased undesirably, the overload state of the motor 54 can be detected due to the variation of the current across the resistor R26 and the transistor Q6 is thus rendered conductive. In this case, the motor driving level outputted at the port PA2 of the microprocessor 124 is changed to a low level to inhibit the motor 54. Under the overload state of the motor 54, the microprocessor 124 checks the level of the current across the resistor R26 (i.e., the condition of transistor Q6 to be rendered conductive). As a checked result, if the overload of the motor 54 is removed, then the microprocessor 124 outputs the high level signal through the port PA2 to run the car normally.

Meanwhile, the steering wheel 28 upwardly extending from the car body 10 at the front of the seat 12 is used to change the direction of running the car. The steering force of the steering wheel 28 is transferred to the upper steering shaft 30a and the spring 40 having the upper and lower ends fixed to the spring receptacle 46 defined between the lower side of the upper steering shaft 30a and the upper side of the lower steering shaft 30b. Therefore, the spring 40 is twisted toward the steering rotation direction and the lower steering shaft 30b is also interlocked to the spring 40. Consequently, the first driven gear 42 coupled to the lower end of the lower steering shaft 30b is operated so that the second driven gear 44 engaged with the first driven gear 42 and the cylindrical gear 74 formed on the upper side of the housing 66 is rotated to turn the housing 66.As a result, the car can be turned in direction.

During the operation of the car, the microprocessor 124 constantly checks the overdischarge of the battery 108.

If overdischarge of the battery 108 is detected by the overdischarge detector 120, the microprocessor 124 mutes the melody to output the alarm signal informing the overdischarge state of the battery 108. When the DC adapter is connected to the jack 106 to charge the battery 108, the microprocessor 124 inhibits the movement of motor 54 and control the cyclic charging mode for the battery 54 while checking the overcharge of the battery 108 by the overcharge preventing circuit 120. After the completion of the cyclic charging mode for the battery 108, the car can run again according to the connection of the power switch 22.

As previously described, the car can be automatically turned in direction by the driving unit 52 even if it is in contact with an obstacle. Accordingly, the car can run in a small space effectively. Furthermore, since the car body has the seat 12 provided thereon, the driver can sit in the seat 12 safely.

A second embodiment of the present invention will now be described with reference to Figure 8 which shows an electromotive car in the form of a cradle, Figure 9 shows a modified example of embodiment of Figure 8, in which a driving unit is arranged at the bottom of the front of the car and Figure 10 shows schematically the driving unit employed in the Figures 8 and 9 embodiments.

Referring to Figures 8 and 9, the steering wheel 28, steering shaft 30 and associated manual steering components of the first embodiment previously described are not employed and-a bed on which a baby can lie is substituted for the seat 12. The cradle can be automatically operated by applying the same control unit as that in the first embodiment without the operation of the steering unit.

Similarly, in this embodiment the cradle can be turned in direction when it comes into contact with an obstacle, as will be described below.

First, the driving unit 52 which is coupled to the motor 54 has a small driving gear 56 mounted on the shaft of the motor 54 as is shown in Figure 10. A large gear 58 such as a helical gear is engaged with the small gear 56. A shaft 60 is rotatably mounted at a central portion of the large gear 58, and shaft fixing bearings 82a and 82b are disposed at both sides of the large gear 58. The shaft 60 as in Figure 5 is vertically extended through a shaft hole 76 formed at the upper side of the housing 66. A horizontal bevel gear 62 is attached to one end of the shaft 60 through a pair of shaft fixing bearings in the housing 66.

Furthermore, a bushing 84 is located between the shaft fixing bearing 78 and the horizontal bevel gear 62 to prevent the horizontal bevel gear 62 from being upwardly moved. A vertical bevel gear 64 is engaged with the horizontal bevel gear 62 and a wheel shaft 70 is inserted in a centre of the vertical bevel gear 62 in such a way that it projects outside of the housing 66. Also, a pair of steerable wheels are attached at both ends of the wheel shaft 70. The small gear 56 and the large gear 58 are contained in a gear box 88 which is bolted to the car body 10 by means of screws 86. A bearing member 90 for ensuring a smooth rotation of the wheel shaft 70 are provided at opposite sides of the housing 66 through which the wheel shaft 70 is projected.

Furthermore, the cradle has the same electrical circuit as that in the first embodiment as is shown in Figures 6 and 7 so as to provide the melody in running the cradle, prevention of the overcharge and overdischarge for the battery 108, the control of the motor 54 and the automatic direction control in contacting with the obstacles.

A description will now be given of the operation of the cradle of Figures 8 to 10.

By connecting the power switch 22, the motor 54 is operated to run the car while the melody is sounded through the speaker SP under the control of the microprocessor 124.

In accordance with the operation of the motor 54, the small gear 56 fixed on the shaft of the motor 54 cooperates with the large gear 58 and the shaft 60 connected to the large gear is then rotated. As a result, the horizontal bevel gear 62 in the housing 66 is rotated by the shaft 60.

Consequently, the wheel shaft 70 is rotated to operate the steerable wheel 72, thereby running the car body (i.e. the cradle).

During the run of the cradle, when the car body 10 comes into contact with an obstacle and the load of the motor 54 is overly increased, the housing 66 is rotated in a direction where the load of the motor 54 is reduced so that the car body 10 can run continuously. At this time, the microprocessor 124 checks the load of the motor 54 so as to prevent the motor 54 from being operated under the overload condition, as is described in connection with Figure 7. After the cessation of the overload of the motor 54, the car body 10 runs under the control of the microprocessor 124.

As previously described since the car is automatically propelled by the electric motor, parents having at least one infant will have more spare time.

Furthermore, since the car sounds various melodies whilst running, emotion of the infant can be excellent.

Although the present invention has been described with reference to the specified embodiments, it will be noted that various modifications and changes can be made without departing from the spirit and scope of the invention. For example, a pedal which is coupled to the variable resistor may be provided at the lower side of the front of the seat to control the car running speed. In addition, an obstacle detecting sensor may be used to turn the car before the contact of the car with an obstacle.

Claims

CLAIMS:

1. An electromotive car for infants, comprising a car body having a pair of front wheels and rear wheels attached at a front and rear side of a bottom plate thereof, the wheels being arbitrarily driven in running the car, the front wheels being in a non-contact relation with the ground and the rear wheel being in a contact relation with the ground, a driving seat, a steering means having a steering wheel for changing the car running direction and steering force transmission means for receiving the steering force produced by the steering wheel, the steering wheel being disposed in front of the driving seat, an electromotive drive means built in the car body for producing a driving force required to run the car, a drive means for running the car along the direction steered by the steering wheel and for automatically changing the car running direction upon increased load on the drive means, a rechargeable power supply means for supplying the operating voltage to the car, and a control means for producing various melodies during running of the car, varying the speed of the electric drive means and determining the overcharge and overdischarge of the power supply means.

2. An electromotive car as claimed in claim 1, wherein the steering means further includes a steering shaft integrally connected to the steering wheel, a steering force transmission member connected to the steering shaft for transferring the steering force from the steering wheel to the drive means, a first driven gear fixedly engaged to a lower end of the steering shaft and a second driven gear for transferring the steering force from the steering wheel to the drive means, and transferring the driving force from the driving means to the steering wheel.

3. An electromotive car as claimed in claim 2, wherein the steering force transmission member comprises a spring, each of said upper and lower steering shafts has a spring receptacle having a spring fixing projection, each projection having a spring fixing groove for receiving opposite ends of the spring.

4. An electromotive car as claimed in any one of the preceding claims, wherein the driving means comprises a large gear engaged with a small gear mounted on a driving shaft of the electric drive motor for transferring the driving force from the drive means, the large gear being a helical gear and the small gear being a worm gear, a horizontal and a vertical bevel gear engaged in a mutually intersecting direction and rotated by way of a shaft fixedly attached to the large gear, a pair of steerable wheels mounted at respective ends of a propulsion axle and driven by the bevel gears, the propulsion axle being fixedly fitted through a centre of the vertical bevel gear, and a housing having a shaft insertion aperture formed at the centre of an upper projection thereof, a threaded gear defined on a periphery of the upper projection and a propulsion axle insertion aperture formed at a predetermined position on a lower side thereof, the gear on the periphery being engaged with the second driven gear of the steering means and the bevel gears being accommodated in the housing, wherein the housing is rotated by the load of the steerable wheels increased when the car is affected by an obstacle.

5. An electromotive car as claimed in any one of the preceding claims, wherein the control means comprises an oscillator for generating a cyclic charging signal for said power supply means, an overcharge preventing circuit for detecting an overcharged state of the power supply means, a charging state detector for checking a charging operation state of the power supply means, a speed controller for setting the speed of the electric drive means, a microprocessor for producing various melody sounds whilst running the car and outputting a control signal to drive the electric drive means, a drive means for driving the electric drive means under control of the microprocessor, and an overdischarge detector for detecting an overdischarged state of the power supply means.

6. An electromotive car as claimed in claim 5, wherein the drive means comprises a resistor through which a high current flows upon overload of the electric drive means and a switching transistor which is rendered conductive due to the increased current through the resistor to transfer the overload of the electric drive means to the microprocessor.

7. An electromotive car in the form of a cradle, comprising a car body having a pair of front wheels and rear wheels attached at a front and rear side of a bottom plate thereof, the wheels being arbitrarily driven in running the car, the front wheels being in a non-contact relation with the ground and said rear wheels being in a contact relation with the ground, a bed having a seat back, an electric drive means built in the car body for producing a driving force required to run the car, a drive means for running the car along the direction steered by the steering wheel and for automatically changing the car running direction upon increasing on the drive means, a rechargeable power supply means for supplying the operating voltage to the car; and, a control means for producing various melodies during running of the car, varying the speed of the electric drive means and determining the overcharge and overdischarge of the power supply means.

8. An electromotive car as claimed in claim 7, wherein the driving means comprises a large gear engaged with a small gear mounted on a driving shaft of the electric drive motor for transferring the driving force from the drive means, the large gear being a helical gear and the small gear being a worm gear, a horizontal and a vertical bevel gear engaged in a mutually intersecting direction and rotated by way of a shaft fixedly attached to the large gear, a pair of steerable wheels mounted at respective ends of a propulsion axle and driven by the bevel gears, the propulsion axle being fixedly fitted through a centre of the vertical bevel gear, and a housing having a shaft insertion aperture formed at the centre of an upper projection thereof, a threaded gear defined on a periphery of the upper projection and a propulsion axle insertion aperture formed at a predetermined position on a lower side thereof, the gear on the periphery being engaged with the second driven gear of said steering means and the bevel gears being accommodated in the housing, wherein the housing is rotated by the load of the steerable wheels increased when the car is affected by an obstacle.

9. An electromotive car as claimed in claim 7 or 8, wherein the control means comprises an oscillator for generating a cyclic charging signal for said power supply means, an overcharge preventing circuit for detecting an overcharged state of said power supply means, a charging state detector for checking a charging operation state of the power supply means, a speed controller for setting the speed of the electric drive means, a microprocessor for producing various melody sounds whilst running the car and outputting a control signal to drive the electric drive means, a drive means for driving the electric drive means under control of the microprocessor, and an overdischarge detector for detecting an overdischarged state of the power supply means.

10. An electromotive car as claimed in claim 9, wherein the drive means comprises a resistor through which a high current flows upon overload of the electric drive means and a switching transistor which is rendered conductive due to the increased current through the resistor to transfer the overload of the electric drive means to the microprocessor.

11. An electromotive car for infants comprising driving wheels mounted on the car body which can be swivelled automatically relative to the direction of travel of the car upon detection of an obstruction so as to change the direction of travel to avoid the obstruction.

12. An electromotive car for infants substantially as described herein with reference to the drawings.