Patent Grant
7607500
This disclosure pertains to amusement rides, especially of a type known as “bumper cars.” More specifically, the disclosure pertains to, inter alia, electrically powered bumper cars each carrying its own source of electrical power. Such electrically powered bumper cars are termed herein “internally electrically powered.”
Amusement rides known as “bumper cars” have been known and enjoyed for many years. (For example, certain models in the past were known as “Dodgem Cars” and “Glidabouts.”) A modern bumper car is a self-propelled, steerable vehicle usually intended to carry one or two riders around in an arena or the like without having to confine the vehicles to a track. The vehicles are individually equipped with compliant but resilient shock-absorbing structures (“bumpers”), mounted usually around the periphery of the vehicle, that allow the bumper cars to engage in collisions and the like without injury to the riders or damage to the cars, and without tipping the cars over. An exemplary type of bumper is disclosed in U.S. Pat. No. 5,516,169 to Falk et al., incorporated herein by reference. Whereas most types of conventional bumper cars are electrically powered, some are powered by small gasoline engines.
Most conventional electrically powered bumper cars are “externally” powered, i.e., powered by electrical current supplied to the bumper cars from a stationary source such an electrified floor or electrified floor and ceiling. An exemplary electrified floor is disclosed in U.S. Pat. No. 6,581,350 to Dean, incorporated herein by reference. In the '350 patent, direct-current electrical power is conducted from the floor to the cars via electrical pickups (“shoes” or “brushes”) beneath the cars that remain in sliding contact with the floor as the cars are being driven around on the floor.
One type of conventional externally powered bumper car comprises a frame to which are mounted the bumpers and a body including a seat for the rider. Also mounted to the frame, below the level of the seat, are driving wheels and stabilizing wheels (e.g., caster wheels). The driving wheels move the bumper car around the floor while the stabilizing wheels stabilize the car relative to the floor. Also mounted to the frame is a DC electric motor that runs continuously while the bumper car is being driven. Power from the motor is selectively delivered to the driving wheels via respective hydrostatic transmissions. The respective amounts of driving power delivered by the transmissions to the wheels are individually controlled by mechanisms, such as respective control levers, that are coupled to the transmissions, mounted to the frame, and manipulated by the rider. The rider steers the car by selectively applying, via the control levers gripped by the rider's hands, driving power to each driving wheel. In this type of bumper car, the manner in which driving power produced by the motor is delivered to the driving wheels is mechanically inefficient. The inefficiency is masked because the bumper car can draw as much current as it ever needs from the conductive floor. But, on the other hand, the bumper car can only be operated on a conductive floor, which imposes limitations and additional costs on use of the bumper car.
Another type of conventional bumper car is similar to the type summarized above, except that the electric motor is replaced with a gasoline motor. Use of a gasoline motor allows the bumper car to be operated on a non-electrified surface, but the mechanical inefficiencies are still present.
Other conventional bumper cars are configured for operation on a non-electrified surface by supplying electrical current from a battery mounted on and carried by the car. Unfortunately, to date, battery power for bumper cars has been disappointing for any of several reasons, as summarized below.
One conventional type of battery-powered bumper car utilizes a DC motor coupled via a gear box and chain-drive to a drive wheel. Steering is achieved by turning, via a first control, the entire mechanism of motor, gear box, and drive wheel. Motion and braking of the bumper car is achieved by manipulating a second control that turns the motor on and off. As noted above, normal use of a bumper car is characterized by a large number of rapidly executed starts, stops, directional maneuvers, and “bumps” into other bumper cars and walls. Driving the bumper car into a stationary wall or into another car can cause an abrupt stall (halt in rotation) of the motor even though power is still being delivered to the motor. At the moment of a stall, the motional emf of the motor drops to substantially zero, which causes the motor to draw a very large current (surge current) that is limited only by the inductance and resistance of the motor windings. Draw of surge current also occurs during starts of the bumper car from a stopped position and during rapid transitions from forward to reverse and vice versa. The large number of such draws of surge current accompanying normal use of the bumper car causes rapid battery drain (and if prolonged can cause overheating and failure of the motor). Consequently, the bumper car must be taken out of service frequently for recharging of the battery. Also, the manner of coupling the motor to the drive wheel is mechanically inefficient, and the steering mechanism in this type of bumper car is incapable of executing 360° spins “on a dime,” as currently desired in bumper-car rides.
Another type of conventional battery-powered bumper car comprises a small DC motor to which are coupled two gear boxes. Each gear box drives a respective drive wheel via a respective drive belt or chain. Forward, reverse, and steering motions of the car are achieved by manipulation of controls coupled to the gear boxes. In the course of driving the bumper car in rapid start, stop, and reverse maneuvers, surge current being delivered to the motor is reduced by use of hydraulic motion limiters in the controls. The motion limiters impose limits on the rate at which the rider can change motion of the car (e.g., impose a time delay in shifting from forward to reverse). This mechanism is complicated and inherently reduces the responsiveness of the car. Hence, this mechanism is used mainly on small, low-mass bumper cars intended to be ridden by very light-weight riders (namely, small children). Loads imposed by larger and heavier riders result in unacceptable rates of battery drain and render the bumper cars too unresponsive for acceptance by older children and adult riders.
Therefore, there is a need for bumper cars that are internally electrically powered while exhibiting an acceptable operational life of the portable source of electrical power carried by each car, without causing any significant detriment to the maneuverability and other performance features that riders expect from such amusement rides.
The need articulated above is satisfied by any of various “internally electrically powered” bumper cars as disclosed herein. The term “internally” used in this context simply denotes that the car carries its own electrical power rather than obtaining power from an external source such as a conductive floor. “Internally” does not necessarily mean that the power source is hidden or otherwise internal with respect to a housing or the like. An embodiment of such a bumper car comprises a frame, a seat, a portable source of electrical power, multiple drive wheels, a motor controller, and at least one rider control. The seat is attached to the frame and configured to hold and position at least one rider of the bumper car. The portable electrical source is mounted to the frame and provides electrical power for propelling the bumper car. The multiple drive wheels are mounted to the frame. Each drive wheel comprises a respective hub motor that, when supplied with electrical power from the source, rotates the respective drive wheel relative to the frame and thus propels the bumper car. The motor controller is connected to the source and to the hub motors. The motor controller is configured to perform at least the following: (a) limit a maximal current, supplied by the source to the hub motors during a surge-current situation, to a preset maximum, and (b) ramp down the maximal current, over a preset time interval, during the surge-current situation. The at least one rider control is interconnected with the source, the hub motors, and the motor controller. The at least one rider control is configured to be manipulated by a rider for propelling and maneuvering the bumper car.
The motor controller desirably is further configured to limit a steady-state current, supplied to the hub motors during actual running of the motors, to a preset value that is lower than the maximal current.
Alternatively, the motor controller is configured to perform at least two of the following: (a) limit a maximal current, supplied by the source to the hub motors during a surge-current situation, to a preset maximum, (b) ramp down the maximal current, over a preset time interval, during the surge-current situation, and (c) limit a steady-state current, supplied to the hub motors during actual running of the motors, to a preset value that is lower than the maximal current.
The bumper car desirably further comprises a bumper mounted to and extending substantially circumferentially around the frame, for cushioning impacts of the bumper car with other objects.
The source of electrical power desirably comprises at least one battery, most desirably multiple batteries. The multiple batteries desirably are arranged in pairs, wherein each pair is connected so as to provide, in a selectable individual manner, electrical power to the hub motors. Thus, when one pair is supplying the electrical power to the hub motors, the other pair can be off-line (not supplying electrical power to the hub motors), and vice versa. By way of example, the source of electrical power can comprise a first battery set and a second battery set, wherein the sets are connected so as to provide, in a selectable individual manner, electrical power to the hub motors, such that, when the first battery set is supplying the electrical power to the hub motors, the second battery set is off-line, and vice versa. In one embodiment the first battery set comprises two respective batteries, and the second battery set comprises two respective batteries. In each battery set, the respective batteries desirably are connected together in series.
Bumper cars comprising multiple, selectably usable battery sets desirably further comprise a battery-selector switch interconnected with the battery sets. In one embodiment the battery-selector switch has a first selectable position allowing electrical power to be drawn from the first battery set to the hub motors, and a second selectable position allowing electrical power to be drawn from the second battery set to the hub motors.
The rider control can have any of various configurations such as joysticks, dual potentiometer controls, or other suitable configuration. In one embodiment two joysticks are used. In this embodiment the multiple drive wheels comprise a left drive wheel and a right drive wheel. A first joystick is connected so as to control operation of the left drive wheel, and a second joystick is connected so as to control operation of the right drive wheel. The first joystick desirably is situated to be manipulated by the left hand of the rider, and the second joystick desirably is situated to be manipulated by the right hand of the rider, independently of the first joystick.
By way of example, a bumper car embodiment comprises an internal power source that produces 24 VDC. In this embodiment the respective hub motors are configured to run on the 24 VDC for rotating the respective drive wheels. Further by way of example in this 24 VDC-powered embodiment, the motor controller is configured: (a) to limit the maximal current supplied to the hub motors during a surge-current situation to a preset maximum in the range of 25 to 30 amps, (b) to limit the steady-state current, supplied to the hub motors during actual running of the motors to a preset value in the range of 5 to 20 amps, and (c) during the surge-current situation to ramp down the maximal current to the steady-state current over a preset time interval in the range of 1 to 3 seconds.
According to another aspect, methods are provided for propelling and steering a bumper car. An embodiment of such a method comprises providing a bumper car with first and second drive wheels powered by first and second hub wheels, respectively, that are integral with the first and second drive wheels, respectively. Also provided is a source of electrical power carried by the bumper car (i.e., an “internal” source of electrical power). Delivery of electrical power from the source to the first and second hub motors is controlled so as to energize the hub motors in a selective manner serving to propel the bumper car and to perform steering of the bumper car, while: (a) limiting a maximal current supplied by the source to the hub motors, during a surge-current situation, to a preset maximum, and (b) ramping down the maximal current over a preset time interval during the surge-current situation. It also is desirable to control delivery of electrical power from the source to the first and second hub motors in a manner that limits a steady-state current, supplied to the hub motors during actual running of the motors, at a preset value that is lower than the maximal current.
The source of electrical power desirably is provided by at least a first and a second battery that can be selectively used for powering the hub motors, as summarized above.
The foregoing and additional features and advantages of the subject apparatus and methods will be more apparent from the following detailed description, which proceeds with reference to the accompanying drawings.
This disclosure is set forth below in the context of representative embodiments that are not intended to be limiting in any way. Words of relative position, such as “vertical,” “horizontal,” “above,” “below,” “over,” “under,” “front,” “rear,” and the like are used to facilitate comprehension of structure by using as a frame of reference a bumper car in a normal-use position. However, these terms are not to be construed as imposing any absolute relationships that persist under all conceivable situations.
Bumper cars as described herein are configured to address the following considerations:
First, to provide maximal maneuverability, the bumper cars are provided with two drive wheels, instead of one as in certain conventional bumper cars. The drive wheels desirably are spaced apart from each other on a horizontal axis. The horizontal axis desirably is bisected by a vertical axis passing substantially through a center of gravity of the bumper car and rider. (It is not necessary that the vertical axis intersect the horizontal axis, but these axes desirably are situated such that differential rotation of one drive wheel relative to the other drive wheel provides a desired highly responsive maneuverability of the cars, including 360° turns “on a dime,” e.g., about the vertical axis.)
Second, to provide maximal mechanical efficiency, each drive wheel is driven by a respective integral “hub motor.” Each hub motor is a combination of an electric motor and a gear train (typically a planetary gear train) in the hub of the respective drive wheel so as to couple the motor directly to the drive wheel. Use of hub motors eliminates the need for external gear trains, transmissions, clutches, chains, belts, and/or other efficiency-robbing mechanical couplings between the motor and respective drive wheel. Thus, each drive wheel is integral with its respective hub motor, yielding a substantially greater mechanical efficiency with which the cars are driven. Such high efficiency correspondingly reduces the power appetite of the bumper car, which is highly desirable in a battery-powered or other internally electrically powered bumper car.
Third, each bumper car is powered by a portable (“internal”) source of electrical power, i.e., each bumper car carries its own source of electrical power with it and on it instead of obtaining power from an external source such as an electrified floor. The typical portable supply comprises one or more devices each conventionally (and in a general sense) called a “battery,” wherein substantially all known batteries produce direct-current (DC) electrical power. Hence, a “battery” as referred to herein encompasses any of various portable sources of electrical power. In general, the portable source of electrical power is mounted to the frame, either directly or indirectly.
Fourth, delivery of electrical power from the source to the hub motors is controlled using a motor controller that provides, for each hub motor, respective limits on starting/surge current (maximum current draw by the motor when starting, including after a stall), surge time (a defined time period during which current flow up to the surge limit is allowed), and steady-state current (after elapse of the surge time, the maximum current allowed during actual running of the hub motor). Thus, the hub motors are driven only when necessary to achieve a desired motion of the car and are operated under controlled current-draw conditions (including during motor-stall situations) that substantially reduce power consumption and yield a correspondingly longer battery life than exhibited by conventional battery-powered bumper cars.
As noted earlier above, at the moment a voltage is applied to a brushed DC motor that is not turning (e.g., during a stall or at rest, both being conditions in which motional emf of the motor is zero), the motor draws a very large current (a “surge” current) that is limited only by the inductance and resistance of the motor windings. As the motor armature begins to turn and picks up speed, the motional emf increases and opposes the flow of current to the motor, which causes the current to fall rapidly from the surge level toward a steady-state value that depends upon the particular motor and the mechanical load being driven by the motor. The surge current being drawn by a stalled or starting motor, especially under mechanical load, can be very high and can cause rapid heating of the motor. A bumper car under normal-use conditions is subjected to a large number of starts and stops in short periods of time. The battery powering the motor(s) must be able to provide the large number of starts and stops required during normal operation of the bumper car. In addition, these many starts and stops must be provided in a manner that does not cause overheating or other damage to the motor(s). The embodiments described below address these concerns.
Turning first to
Regarding the frame 12 and body 16, it is possible to integrate the body and frame in a single unit rather than having a separate body that is attached to the frame; such a single unit would still be regarded as a “frame.” Also, although in this embodiment the seat is configured to hold one rider, in other embodiments the bumper car can be configured to hold more than one rider. In addition although the seat is depicted in this embodiment as being a separate component that is mounted to the body (or frame), in other embodiments the seat is integral with the body or frame. For example, the body 16 can be molded or formed so as to define a seat. In all these various configurations, the seat nevertheless is “attached” to the frame.
In this embodiment the caster wheels 50, 52 desirably are each swivel-mount and four inches in diameter. It will be understood that other types and sizes of “caster wheels” alternatively could be used.
Each of the batteries 64a-64d in this embodiment desirably is a 12 VDC, 32 Amp-hour, sealed type. The four batteries 64a-64d are connected for alternating use in pairs; i.e., when one pair is “on,” the other pair is “off.” In
Each drive wheel 60, 62 comprises a respective hub motor 72, 74 that, in this embodiment, is a brushed 24-volt DC hub motor with an integral brake and integral tire 76, 78. Thus, each drive wheel 60, 62 is integral with its respective hub motor 72, 74. In accordance with achieving intuitive control during driving, the first drive wheel 60 desirably is located on the left side of the frame, and the second drive wheel 6274 desirably is located on the right side.
An exemplary hub motor is XTi® type 280-1342M manufactured by Assembled Products Corp., Rogers, Ark., which is configured to be driven using 24 VDC. This specific type of hub motor has a solid rubber tire having a diameter of eight inches. The stated diameter is not intended to be limiting. For this particular hub motor, the 8-inch tire diameter was deemed advantageous in view of certain factors such as the maximum rotational velocity (150 rpm) exhibited by this motor when driven at maximal power and a concern with limiting the maximal driving velocity of the car. (An 8-inch diameter drive wheel rotating at 150 rpm provides a car-drive velocity of 3,770 in/min=3.57 ml/hr.) Therefore, depending upon the desired driving velocity of the car, the maximal rotational velocity of the hub motor at full power, and the particular hub motors that are commercially available, an appropriate diameter of the driving wheel can be selected. For example, a hub motor having a lower maximal rotational velocity and a correspondingly larger tire diameter could be used, so long as the motor is able to provide sufficient motive power to the bumper car at an acceptable rate of power consumption. The tire need not be solid; alternatively, it can be pneumatic, for example.
The hub motors 72, 74 also desirably have integral brakes that are actuated whenever power to the motors is interrupted. Thus, the integral brakes operate in a fail-safe mode in which the brakes are off whenever power is being supplied to the motors and the brakes are on whenever power is not being supplied to the motors. This is especially desirable because the brakes, when on, prevent the car from moving while a rider is either exiting or entering the bumper car. Further desirably, the brakes are configured with an override feature (e.g., a manually operated control on each hub motor) to allow the cars to be moved when “off,” such as during an emergency situation. Since these types of integral brakes draw a certain amount of power to maintain them in an “off” state whenever the hub motors are “on,” the power consumption of the brakes in the hub motors should be taken into consideration in determining the amount of DC power to be provided by the battery or batteries. For example, the brakes on the exemplary hub motors noted above draw about 0.8 amp at 24 VDC.
DC power to the hub motors 72, 74 in this embodiment is supplied by a selected pair of batteries 64a-64b or 64c-64d via a respective controller (or via a respective channel of a single controller 68). As noted above, a stalled motor normally draws maximal current until power to the motor is disconnected. This situation could have serious power-dissipation consequences for a semiconductor-based controller being used to control the motor. The controller 68 desirably is semiconductor-based but is configured to control each bi-directional load (i.e., each respective hub motor that can move in forward and reverse directions) while simultaneously limiting the following parameters for each load: starting/surge current, steady-state current, and surge time. By imposing these limitations, both the controller 68 and the motors 72, 74 escape the hazards of surge currents.
For this particular bumper-car embodiment, exemplary levels for the controller parameters are as follows (at 24 VDC): starting/surge current: 25 amps, steady-state current: 10 amps, and surge time: 2 seconds to drop from 25 to 10 amps. Representative ranges for a car sized to carry an adult rider are 25-30 amps for starting/surge current (approximately 15 amps for a smaller car for small-child riders), 5-20 amps for steady-state, and 1-3 seconds surge time. If a surge-current or otherwise high-current situation is detected by the controller 68, the controller reduces, over a preset amount of time, the power delivered to the respective load. Thus, maximal current supplied to the hub motors during a surge-current situation is: (a) limited to a preset maximum appropriate for the particular hub motors, and (b) automatically ramped down, rather than abruptly shut off, over a preset time interval during the surge-current situation. (The longer the time interval, the more time consumed in reducing the current from a surge level to the steady-state level.) Also, steady-state current supplied to the hub motors during actual running of the motors is limited to a preset value that is lower than the surge maximum.
Example types of controllers offering such performance are triac-based controllers, chopper-based controllers, and full-bridge-based controllers. In the case of a triac-based controller, a respective triac can be used to control each motor, or a respective triac can be used to control each rotational direction of each motor. Each triac can be controlled using, for example, a control IC (integrated circuit) or a microcontroller. Many chopper circuits utilize chopper MOSFETs that control the rate and duration of application of current to the motor. This type of circuit can incorporate a “soft-start” feature, in which the motor is set in motion over a period of time, rather than instantly, by application of periodic bursts of current to the motor, and surge currents are avoided by initially allowing the chopper MOSFET to conduct for only short periods of time. The full-bridge-based controller circuit achieves forward, reverse, and braking control of the motor, typically using four MOSFETs that are controlled using a microcontroller. The MOSFETs apply packets of current to the motor in a manner by which the frequency and duration of the packets are controlled by the microcontroller.
An exemplary controller 68 is the “Dual30” two-channel controller manufactured by Courtney Electronics, Greenland, Ark. This particular controller can independently control two hub motors 72, 74, connected as shown in
In general, the controller 68 can be used with any of various input schemes, such as a joystick-based input scheme, a dual-potentiometer input scheme, or an active-low switch input scheme. An active-low switch input scheme is shown in
For this particular bumper-car embodiment, a joystick-based input scheme is desirable because it provides directional and speed controls in a manner that is familiar to most riders. For example, any joystick that produces two analog outputs may be used so long as the controller 68 is properly programmed. An exemplary joystick connection for the first motor 72 is shown in
An exemplary dual-potentiometer input scheme is shown in
An electrical schematic of an embodiment of a circuit by which joysticks 110, 112, the controller 68, and the hub motors 72, 74 are interconnected is provided in
On the first (left-hand) joystick 110, the two “common” (COM) terminals are connected to the ground conductor 132, the front normally open (N.O.) terminal is connected via a conductor 133 to pin 96 (P2) on the controller 68, and the rear N.O. terminal is connected via a conductor 134 to pin 98 (P3) on the controller. Similarly, on the second (right-hand) joystick 112, the two COM terminals are connected to the ground conductor 132, the front N.O. terminal is connected via a conductor 135 to pin 102 (P5) on the controller 68, and the rear N.O. terminal is connected via a conductor 136 to pin 100 (P4) on the controller. As noted above, the normally closed (N.C.) terminals on the joysticks 110, 112 are not used in this embodiment.
An electrical schematic of the wiring of the batteries 64a-64d and associated electrical components is shown in
As noted above, in alternative embodiments, two batteries can be used, wherein each battery is used in place of a respective pair of batteries used in the depicted embodiment. Yet further embodiments can employ only a single battery. Also, the battery or batteries are not limited to 12 or 24 VDC output. Other voltage outputs can be used as appropriate for the particular bumper car (and hub motors of the car), the conditions under which the car will be used, and the prevailing level of battery technology. Changing the battery voltage likely will necessitate a change in the specifications of the hub motors 72, 74; however, such a change is readily accommodated in view of the various types of hub motors that currently are commercially available.
Referring further to
The radio receiver 70 functions as a radio-actuated switch. Whenever the radio receiver 70 receives a respective signal from a remote radio transmitter (not shown), the radio receiver opens or closes an internal switch that breaks or makes, respectively, an electrical connection between the switch input 156 and the switch output 158. Thus the bumper car (as well as other cars in the vicinity, if desired) can be turned on and off remotely (and simultaneously, if desired). Desirably, in the manner of a “fail safe” configuration, the radio receiver 70 opens its internal switch (thereby turning power to the car off) in a situation in which power delivery to the radio receiver is off. If desired, the car can be provided with a bypass switch (not shown, but desirably manually operated) that overrides the radio receiver.
Further with respect to the battery-selector switch 142, a pin 162a is connected to a “−” coil input 166 of the second solenoid 66b, and a pin 162a is connected to a “−” coil input of the first solenoid 66a. The first solenoid 66a receives “+” coil power via a “+” coil input 170 that is connected to the power-input lug 148a. Similarly, the second solenoid 66b receives “+” coil power via a “+” coil input 172 that is connected to the power-input lug 148b. Thus, the respective coils of the solenoids 66a, 66b receive constant “+” power from the main fuse block 146 but switched “−” power from the battery-selector switch 142. Furthermore, via the second pole 164, the radio receiver 70 always receives “+” power, supplied by either the pin 164a or the pin 164b of the battery-selector switch 142. Thus, the battery-selector switch 142 is a DPDT switch providing selective control of the particular pair of batteries being used for powering the car, without interrupting power to the radio receiver 70.
The batteries are recharged by connection of a conventional recharging unit (not shown) to a charging-plug assembly 174. The recharging-plug assembly 174 comprises two plugs 176, 178. Each plug 176, 178 has a respective first pin 176a, 178a connected to “−” battery power via the ground block 114 as shown, and a respective second pin 176b, 178b connected to “+” battery power via the main fuse block 146 as shown. Application of charging power to the plug 176 recharges the pair of batteries 64c, 64d, and application of charging power to the plug 178 recharges the batteries 64a, 64b.
Testing under normal actual-use conditions has revealed that bumper cars within the scope of the instant disclosure, configured according to the representative embodiment, and having new batteries with a full charge operating under normal-use circumstances, will provide approximately 100 ride cycles (each being 2 minutes in duration, with an approximately 30-second pause between each cycle to allow exchange of riders) per pair of batteries. Thus, the four batteries 64a-64d can supply adequate power to the bumper car for approximately 200 2-minute ride cycles per full battery charge. This is two to six times the usable life, per charge, of conventional battery-powered bumper cars.
Internally powered bumper cars as described herein offer substantial latitude in terms of locations and conditions of use of the cars. For example, internal power allows the bumper cars to be used on various surfaces not limited to conductive floors and the like. That said, it is nevertheless is possible for bumper cars having hub motors as described herein to obtain power from a conductive floor or analogous means. Another advantage of internal power such as a battery pack is that the delivered power is substantially free of potentially harmful voltage fluctuations, spikes, and the like. If the cars are powered externally, such as via a conductive floor, desirably either the bumper cars include circuitry for filtering the delivered power or the external power supply itself (i.e., supplying power to the floor) is filtered sufficiently for use by the motor controller.
Whereas the subject bumper cars and other aspects have been described above in the context of representative embodiments, the invention is not limited to those embodiments. On the contrary, the subject bumper cars and other aspects are intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention, as defined by the appended claims.
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|---|---|---|---|
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| Number | Date | Country | |
|---|---|---|---|
| 20070209851 A1 | Sep 2007 | US |
