Patent Application
20160009135
Not Applicable.
Small vehicles powered by electricity from batteries or other means offer the solution to city traffic congestion and pollution problem. In fact, very high percentage of vehicles driving on the highway or city streets, especially in the United States, have no more than two occupants. This means that these low occupied vehicles moving on the streets can be replaced by two seat smaller vehicles to lower fuel consumption and lower the pollution level. However, small vehicles typically are not safe to drive on the streets where a lot of big trucks, big SUVs and regular size sedans are also sharing. To make small vehicles safe to drive on the streets, special design for collision prevention should be implemented up to a level that the general public can accept before we see small two seat vehicles widely show up on the streets.
For example, a U.S. patent application US20070164583 presents a design in which vehicle body can be expanded to a bigger size for collision protection during highway driving and shrink back to small size for narrow street driving. The drawback of this design is that, while the vehicle body can be expanded bigger to provide more cushion, the collision protection may not strong enough and it is difficult to make the shell of the vehicle looks appealing.
U.S. Pat. No. 7,780,197 presented a way to extend the front wheels and rear wheels by using telescoping tube structure. The drawbacks of this design is that it still uses a single steering mechanism with rods connecting to both front wheels, thus the complex nature of the mechanism for a heavy farm tractor will be difficult to maintain the rigidity of the structure. The tube axle will also have difficulty to bear the load of the heavy tractor because when it expands outward, the portion left in the frame tube will be very limited because the frame tube needs to contain left and right hand axle tubes, particularly for the rear axle due to the existence of the differential gear. It is easy to see that such expandable axle design is not possible for a small vehicle having a very narrow track such as 42″ to begin with.
Considering that most high speed race cars have a design that typically having a small chassis supported by four wheels which span much wider track width than the width of the chassis, it offers a clue to make a smaller car very stable to drive in high speed and at the mean time it also offers some protection for the chassis from the wider track of four wheels, as well as passengers inside the cars. This idea is particularly useful for developing a small electric vehicle which does not need as much electric power as a traditional vehicles having capacity of four or five passengers. Therefore, it is intuitively true that a design for a small vehicle seating two persons in tandem which is capable of changing its track width to a narrow track for narrow street driving and wide track width for high speed driving would be an ideal small electric car in the near future. A similar design for such purpose is shown, for example, in U.S. Pat. No. 8,746,388. The major disadvantages of design in the above mentioned patent is that it widens the track of front wheels only, not front and rear wheels at the same time and is thus not able to provide as much collision protection and stability as desired. Another disadvantage is that the mechanism to support the track width change, combined with originally equipped suspension and steering mechanism, becomes very complicated and the rigidness of such structure could face big challenge during high speed driving in addition to questionable durability problem.
Electric cars using batteries or fuel cells are gradually considered as a way to solve pollution problem in urban area. However, battery power are still very expensive in terms of reasonable driving range between recharges for a normal five seat sedan. To make electric popular among all drivers, smaller cars with enough collision protection is the way to go; daily commute to work does not need a full sized car.
The purpose of current invention is to provide a set of front wheel and axle assembly and a set of rear wheels and axle assembly for a small vehicle, preferably a electric vehicle with two seats in tandem, such that it can be driven safely with high speed on the highway with expanded track width, yet small enough to tour in narrow streets with retreated narrow track. The no-emission small vehicle is also intended for small parking space, even can be driven into an apartment in a high rise building to save the owner from buying an expensive parking space in big city.
Further more, the intended application of the invention is for electric cars with no emission, small size of such vehicles make them particularly easy to solve parking problem—they don't need to park in conventional parking space. They can even be driven into elevator and parked in the lobby area of a big building, provided that the building is equipped with elevator big enough to carry the vehicle to all levels in the building, thus relieve a lot of city parking problems.
Mention about differential gears for real axles.
A vehicle with two pairs of wheels associated with a front axle and a rear axle respectively, capable of changing track width during moderate moving speed is disclosed. A control means and an actuator can be used to expand or narrow down the track width to predetermined maximum or minimum widths for different driving environment.
Maximum track width condition offers extra collision protection to the chassis and passengers. It also provides additional driving stability by changing wider track width, as normally the cases in Formula 1 racing cars. Minimum track offers the agility for driving in small lanes with speed limits lower than, say, 50 miles per hour or so.
The car is preferably a small one with electric power and two seats in tandem. Such car consume less power, consequently is the solution to most environmental issues and urban congestion problems exist especially in big cities around the world.
It is therefore a primary object of current invention to provide a small two seat vehicle, electric power preferably, to be able to safely drive on the highways along with other bigger vehicles.
Another object of the present invention is to provide a small vehicle which can be driven to narrow downtown alleys with easiness and smaller parking space.
Another object of the present invention is to promote popularity of small electric power cars while the battery capacity is still too expensive for regular automobiles.
Still another object of the present invention is to make the small electric cars popular for big urban areas where the traffic condition and air quality do not allow more regular automobiles with traditional gas power engines.
Yet another object of the present invention is to provide a more affordable, more economical way to commute for most drivers of single occupant vehicles.
A further object for the present invention is provide small vehicles relieve the parking problems for shopping centers.
Theses and other objects of the present invention will become clearer to those skilled in the art as the description proceeds.
In
The same front axle is also shown in
In
Left arm 317, wheel disk 319, link bar 318 and frame 305 form four bar parallel mechanism, hinged at 324w, 320w, 321 and 322 respectively.
The detailed structure of wheel assembly is further shown for parts 303 at n position, where 303n1 is the wheel to be attached to parts 303n2 with 303n3 inserting into the tunnel center hole of 303n1. 303n2 and parts 303n9 form are engaged by the ball joint 303n4 allowing the wheel to be steered by the linkage 303n8 driven by motor operated gear mechanism 303n7. Four bar linkage bars 323n and 315n also connected and hinged to 303n6.
From
The implementation of current invention is to design a low energy consumption small vehicle, particularly an electric power one, which can expand its four wheels to a wider track width, consequently occupy bigger strip of the road than the width of its unchanged chassis in order to avoid the chassis being directly collided when it is driven on interstate highway along with many other much bigger vehicles at speed higher than 60 miles per hour. An ideal design will be to have a wide track width wider than 60″. 62″, for example, is roughly about the same as most compact vehicles traveling on the highway. Taking 62″ as the target wide track width, a narrow track width to match would be reasonably around 36″, which is about the width of most golf carts which seat two people in parallel. However, considering the vehicle implemented under current invention is to travel at speed much higher than golf carts even at narrow track mode, the narrow track width should be a little wider, say, 42″ is more appropriate. Such vehicle would be best designed in style of tandem seating for two person such that each of them will have plenty of space to operate the vehicle or seating behind doing other things. In such proposed design, the track width will expand 10″ each side for a total width expansion of 20″, which will significantly increase ability to prevent the vehicle from tip over in addition to be able to avoid the chassis being collided by other vehicles.
First implementation of the invention is shown in
In
Theoretically, it would be ideal and much simpler to use a double end cylinder in stead of parts 203, 204 and 205 to push or retract the wheels between w and n position. However, hydraulic cylinders are not built to bear forces across its axial direction. In addition, there would be not enough space for the cylinder rods to expand or retract 10″ or more with enough portion to support the weight of the vehicle as analyzed earlier. However, it is possible to design an front axle having two hydraulic cylinders capable of bearing load across cylinder axis. The two cylinders will optimally be part of the vehicle frame and horizontally parallel to each other, and overlap each other as much as possible to support the vehicle weight as mentioned in previous paragraph.
The two front wheels have motor driven linkages 207 and 217 to steer the wheels for driving direction. The synchronism of the steering to these two wheels can be achieved by firmware or software which controls the motors in the parts 207 and 217. Inside the wheels, pivots 202 and 218 respectively are used support the turning from steering action.
To switch from narrow track to wide track or vice versa, there are two ways to achieve that. We can add a hydraulic cylinder with double ends such as parts 209 and its two rods 208 and 216 to expand and retract the wheels to achieve the switches. Or we can use the vehicle momentum directly to achieve same goal.
Since the forces needed to push wheels outward and retract them inward are in axial direction and are orthogonal to the direction of propulsion, special arrangements are needed to create such axial forces to achieve the goal. Intuitively, a hydraulic cylinder which is capable of pushing both ends is clearly a solution, and such parts is shown as hydraulic cylinder 209 in
Apparently, using hydraulic cylinders such as parts 209 is not the only way to expand or retract the track width of wheels. Linear motion device for this purpose includes using gear-rack assembly to force the expansion and retraction of wheels, as well as using hydraulic cylinder like parts 209 to achieve same function. Both ways are very mature and have their own advantages.
However, a preferred implementation to create the axial force components is to control front and rear wheels such that they can turn to open alignment stance, as shown in
To create open or close alignment for front wheels, the linkages used to steer the wheels can be used. However, it should be a control independent of steering operation. In steering the two front wheels simultaneously turn to the same side, right or left, with an angle depends on how much the drive steers to turn. The control to open or close alignment make the two front wheel turn to opposite sides with the same angle, and should be designed to operate automatically, not by a manipulating tool such as a steering wheel. Also, the degree of open or close should depend how big the axial force is needed in order to overcome the friction in sliding inside the frame cylinder 303, and the speed of vehicle in operation. This is a factor which can be predetermined during designing and testing phase; as such a control system should be designed to operate wheel opening angle as a function of vehicle speed.
For rear wheels, the open or close alignment stance can be achieved by having the rear wheel designed as shown in
Ideally, a button should be installed in the front panel of a vehicle so that, when pushed, the control system will automatically sense to expand the track width or to retract it, so that it will start to simultaneously open or close the alignments for front and rear wheels such that the expansion or retraction of the track width of the four wheels will be executed until wide or narrow track width is reached, and the control system will automatically restore open or close alignment to normally parallel stance. Since the travelling length of expanding and retracting will be very short, as in a design of 10″ mentioned earlier, it will take only a short time, say, 10 seconds or so to finish the whole procedure of expansion or retraction. Under such scenario, it is expected that such operation is best conducted when driving at slow speed such as 10 to 20 miles per hour and on a straightforward driving condition. However, it should not consider this as a limitation to current invention, because, physically, even if a vehicle is steered to turn a small angle to the right or left, the front wheels still can be set to an open alignment or close stance to create required force components for expanding or retracting the front wheels. Also, it is theoretically same result if we drive backward with open or close alignment stance, except that it is awkward to do such operation in driving backward.
A second way to make four wheels of a vehicle to have variable track width is to have the wheel-axle assembly and vehicle frame as shown in
To make sure the four wheels of a vehicle will keep parallel to the center line defined by vehicle frame 305 while the axles moving from w to n or from n to w position, a parallel four bar linkage is applied to all four wheels and all of the four linkages naturally include portion of vehicle frame 305 as one of their four bars. The left rear wheel, for example, is guided by the four bar linkage constituted by the arm 317 of rear axle, wheel disk 319, bar 318 and portion of frame 305. The four joint points for the four bar are also show in
Now again the forces needed to move four wheels from w to n position or vice versa can come from two sources, say, from an external motor driven mechanism 313 with a rack 312 as shown in
While mechanism 313 is used to integrally pull or push the four arm as a unit, many other designs are still possible. For example, 313 can be designed to have two separated units, one for front arms and the other for rear arms. Hydraulic cylinders can also be used instead of the rack and pinion mechanisms.
To explain more details about front wheel operation during the movement of bendable axle and front wheel, one of the two front wheel 303 at n position is used for further illustration. Wheel 303n1 is mounted with screws on parts 303n2 as 303n3 penetrates into the center tunnel hole of the wheel. The wheel 303n1 is then can freely turn, pivoting the ball joint 303n4 such that linkage 303n8, controlled by the motor driven oscillating mechanism 303n7, which is operated integrally with the counter parts of another front wheel, serves as the steering mechanism for the vehicle. The right arm of front axle 315n1, connects to wheel shaft 303n9 by a hinge 303n6, makes the bendable right arm 315n1 rotatable under the constraint of four bar linkage which includes portion of 303n9, 323n, 315n and portion of frame 305 to assure 303n9 always keep parallel to body frame 305 when arm 315 move from w to n or from to w position.
When the momentum or momentum change of a the vehicle is considered, the mechanism such as 313 and its four racks become unnecessary. Instead, a control procedure can be set to automatically execute to move the four wheels to w or n position in vehicle moving condition. For example, if the front wheels are partially braked while the propulsion of rear two wheels is on, the vehicle tend to move faster than the front wheels, consequently exerting a reaction force at each front wheel and force its bendable arm to move backward, causing the front wheels move from w to n position. At the mean time, due to the braking action of the front wheels, the vehicle will move slower than it should from the propulsion, resulting a net force at each rear wheel to move ahead of the vehicle, consequently the two rear arms gradually move and engage into n position. Therefore, the action of partially braking front wheels while acceleration pedal is being depressed, the bendable axles will automatically move from w to n position.
We see that, for a rear wheel drive vehicle, forward moving momentum of the vehicle can easily be taken advantages for switching the vehicle from w to n position, given the vehicle design as depicted in
To compare the two implementations depicted in FIGS. A-C and
Although the predetermined wide track and narrow track are different for front axle and rear axle in the setting of current invention, there is no reason they can not be the same.
The embodiments presented above are typical embodiments of current invention. Various modifications can be made without departing from the scope of the invention, which is defined by the attached claims. For example, one of the double sector shapes structure may be turned 180 degrees and still can serve to expand and retract the track width. The vehicle may also comprise more than two axles.
