Abstract:
A hybrid vehicle system having first and second internal combustion engines, first and second flywheels respectively coupled to the first and second internal combustion engines, a plurality of motorized wheels electrically interconnected to first and second flywheels, and a controller connected to the internal combustion engines and to the flywheels and to the plurality of motorized wheels for transferring energy therebetween. Each of the flywheels has permanent magnets affixed to a side of a housing thereof. Each of the flywheels is vacuum sealed within anon-ferrous housing.

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
   The present application claims priority of U.S. Provisional Application Ser. No. 60/759,291, filed on Jan. 17, 2006, and entitled “Flywheel System for Use with Electric Wheels in Hybrid Vehicles”. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC 
   Not applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to hybrid vehicles. More particularly, the present invention relates to the use of motorized wheels in association with such hybrid vehicles. Additionally, the present invention relates to use of flywheels for the storage and release of energy and for the transfer of energy from separate internal combustion engines within the hybrid vehicle. 
   2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
   The need to reduce fossil fuel consumption and pollutants from automobiles and other vehicles powered by internal combustion engines (ICE&#39;s) is well known. Vehicles powered by electric motors have attempted to address these needs. However, electric vehicles have limited range and limited power coupled with the substantial time needed to recharge their batteries. An alternative solution is to combine both an ICE and electric traction motor into one vehicle. Such vehicles are typically called hybrid electric vehicles (HEV&#39;s). 
   The HEV has been described in a variety of configurations. Many HEV patents disclose systems where an operator is required to select between electric and internal combustion operation. In other configurations the electric motor drives one set of wheels and the ICE drives a different set. 
   Other, more useful, configurations have developed. A series hybrid electric vehicle (SHEV) is a vehicle with an engine (most typically an ICE) which powers a generator. The generator, in turn, provides electricity for a battery and motor coupled to the drive wheels of the vehicle. There is no mechanical connection between the engine and the drive wheels. A parallel hybrid electrical vehicle (PHEV) is a vehicle with an engine (most typically an ICE), a battery, and an electric motor combined to provide torque to power the wheels of the vehicle. 
   A parallel/series hybrid electric vehicle (PSHEV) has characteristics of both the PHEV and the SHEV. The PSHEV is also known as a torque (or power) splitting powertrain configuration. Here, the torque output of the engine is given in part to the drive wheels and in part to an electrical generator. The generator powers a battery and motor that also provide torque output. In this configuration, torque output can be produced from either source or both, simultaneously. The vehicle braking system can also deliver torque to drive the generator to produce charge to the battery. 
   The desirability of combining the ICE with an electric motor is clear. The ICE&#39;s fuel consumption and pollutants are reduced with no appreciable loss of performance or range of the vehicle. Nevertheless, there remains substantial room for development of ways to optimize the HEV&#39;s operational parameters. Two such areas of development are engine start/stop and regenerative braking Engine start/stop strategies turn off the engine during times of low power demand from the driver, thereby reducing fuel usage and emission production directly. 
   Regenerative braking (regen) captures the kinetic energy of the vehicle as it decelerates. In conventional vehicles, kinetic energy is usually dissipated as heat at the vehicle&#39;s brakes or engine during deceleration. Regen converts the captured kinetic energy through a generator into electrical energy in the form of a stored charge in the vehicle&#39;s battery. This stored energy is used later to power the electric motor. Consequently, regen also reduces fuel usage and emission production. In certain vehicle configurations, the engine can be disconnected from the rest of the powertrain thereby allowing more of the kinetic energy to be converted into stored electrical energy. 
   Successful implementation of an efficient regen strategy must consider, among other things, the effects of ICE braking on the vehicle. In conventional vehicles, engine braking is well known and is typically characterized by two types of negative powertrain torques including engine friction and pumping losses. Both types of losses result from the engine being driven by the wheels through the powertrain. Engine friction losses result from the piston rings sliding along the cylinder walls and rotation in the bearings of the engine. Engine pumping refers to the compression of the air in each of the engine&#39;s cylinders as the engine moves through its stroke. Engine braking allows the driver to reduce vehicle speed without applying force to the brake pedal. 
   Regenerative braking (regen) is known for conventional ICE vehicles in the prior art. A primitive regen system is described in U.S. Pat. No. 5,086,865 to Tanaka et al. In this patent, a regen controller decouples the engine from the vehicle&#39;s powertrain. Based on vehicle speed and gear selection, an electromagnetic clutch couples the powertrain to a hydraulic pump/motor whereby the vehicle&#39;s kinetic energy is transferred to a high pressure oil accumulator. The pressure can be transferred back to the powertrain during, for example, the next acceleration of the vehicle. 
   Regen in an HEV is also known in the prior art. In U.S. Pat. No. 5,839,533 to Mikami et. al., a rapid response drive source brake controller for engine braking and regen is described. The controller determines the gearshift lever position manually set by the driver (e.g., low gear). The engine&#39;s brake force (negative torque) increases as the speed ratio of an automatic transmission increases. The controller can engage both engine braking and regenerative braking if the manually selected braking exceeds the maximum regen force that can be generated by the electric generator. 
   U.S. Pat. No. 5,915,801, to Taga et al., discloses a regen controller to simulate ICE braking torque. This controller disengages the engine from the powertrain via a disconnect clutch and accumulates braking energy (negative torque) in an on-board accumulator such as a generator and battery. The controller improves the speed and efficiency of the regen by, for example, determining the target braking torque according to the release speed of the accelerator pedal. Thus, when large braking torque is required, the controller makes it possible to produce a large amount of regen without delay even before the brake pedal is depressed. This decreases the need for the driver to operate the manual shift lever to a lower gear or further depress the brake pedal. The controller can additionally use inputs from brake pedal position, vehicle speed, vehicle weight, and gradient information to determine target braking torque. By using the controller during regen, the engine may or may not be connected to the powertrain. If the engine is disconnected during regen, there is no engine friction and pumping. This allows the recapture of even more kinetic energy without exceeding the deceleration limits for the vehicle. Obviously, this is advantageous for an HEV from an energy management perspective. 
   The tradeoff for disconnecting the engine to capture more regen energy is that, with the engine disconnected, the transition back to an engine driving state becomes significantly more complex. If the engine is left connected during regen and the driver depresses the accelerator pedal, it is a straightforward process to restart the engine, if desired, simply by reinitializing fueling of the engine. Any torque disturbance to the powertrain due to the engine restarting would be small, and not completely unexpected by the driver, given the change in demand. Alternatively, if the engine is disconnected from the powertrain during regen, starting the engine would involve maintaining the vehicle&#39;s response to the driver&#39;s demand using the motor while simultaneously closing the disconnect clutch and starting the engine. 
   Torque supply to the powertrain should be transferred from the motor to the engine smoothly in order to avoid any disturbance to the driver. It is therefore necessary to develop a strategy to keep the engine connected to the powertrain during regen if a change in driver demand (from decelerating to accelerating) is anticipated. With two modes of regen possible, it will also be necessary to transition the compression braking torque from the engine to the motor as the engine is disconnected from the powertrain in going from one mode to the other. 
   It is an object of the present invention to provide a hybrid vehicle system having permanently sealed vacuum chambers for the flywheel storage chamber. 
   It is another object of the present invention to provide a hybrid vehicle system which magnetically couples the flywheel shaft to a brushless excitation field generator. 
   It another object of the present invention to provide a hybrid vehicle system that magnetically couples a permanent magnet generator to the flywheel chamber. 
   It is a further object of the present invention to provide a hybrid vehicle system which utilizes two differently sized engines and flywheel storage devices in order to maximize efficiency. 
   It is still another object of the present invention to provide a hybrid vehicle system that provides better power-to-weight ratio through the use of high speed, high-efficiency engines. 
   It is still another object of the present invention to provide a hybrid vehicle system which avoids the use of batteries, ultra-capacitors, or super-capacitors for storage capacity. 
   It is still another object of the present invention to provide a hybrid vehicle system which minimizes the cost and complexity of manufacturing processes through the use of AC induction motorized wheels. 
   It is another object of the present invention to provide a hybrid vehicle system that is more efficient than conventional parallel or series hybrid system. 
   It is still an further object of the present invention to provide a hybrid vehicle system that can utilize various sensed parameters to optimize the performance and efficiency of the operation of the vehicle. 
   It is a further object of the present invention to provide a hybrid vehicle system in which either or both flywheels can be charged through active electrical power electronic controls. 
   It is still a further object of the present invention to provide a hybrid vehicle system which avoids the use of CV joints, transmissions, driving axles, mechanical couplings, differentials and batteries for energy storage. 
   It is also another advantages of the present invention to provide a hybrid vehicle system which provides for 100% regenerative four-wheel braking. 
   These and other objects and advantage of the present invention will become apparent from a reading of the attached specification. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is a hybrid vehicle system that provides a low-cost solution for electric wheel topology through the use of a flywheel for energy storage. In particular, a pair of internal combustion engines are provided which are magnetically coupled to individual flywheel systems. The energy output of the flywheel system can then be transferred to a DC bus which can deliver energy to AC induction motorized wheels. The braking energy of such wheels can also be transferred back through the use of permanent magnets to the flywheels. Suitable control mechanisms are independently connected to the separate internal combustion engines and to the other components of the system so as to regulate and control the flow of energy through the system. External sensors can be connected to the control system so as to provide input information for the proper processing of the system of the present invention. It is believed that the efficiency of the hybrid vehicle system of the present invention is better than any existing hybrid technology. 
   In the present invention, the energy stored is displaced into two separate vacuum-chambered flywheels which are housed in separate material enclosures formed of non-ferrous material. Permanent magnets are embossed into one side of each of the rotating flywheels. The flywheels are magnetically coupled to an AC winding (i.e., a stator) which is mounted stationary to the chassis of the vehicle. The magnetic coupling effect through the non-ferrous material allows for a non-penetrated vacuum chamber that can be permanently sealed for an inexpensive form of flywheel chamber. 
   The opposite end of the rotating flywheel is also magnetically coupled to the rotating shaft of the separate engines by way of a magnetic field coupling. The rotating flywheel has embedded permanent magnets so as to provide the torque flux and is coupled with electromagnetic coils that are fixed to the shaft of the engine. 
   The engine shaft has these electrically-operated coils thereon. The coils are energized by the control system by way of computer command. The coils on the engine shaft operate from a low power use so as to be energized with alternating and reversed magnetic fields and to couple with the rotating flywheel permanent magnet fields through the non-ferrous material of the flywheel housing. In order to achieve the electric current (i.e. the excitation current) to the rotating pole pieces, a low power, stationary DC field is applied to the pole pieces and extending around the rotating shaft. 
   A small multi-phase winding with laminations is affixed to the rotating shaft. The effect of the stationary DC field flux that is imposed onto the rotating multi-phase winding creates an alternating current which is diode-rectified with a rotating bridge rectifier plate. The flywheel assembly is soft-coupled and de-coupled by the controller. The generator end of the flywheel assembly includes a set of permanent magnets that are electro-magnetically coupled through the non-ferrous housing so as to create the necessary magnetic flux which generates the electrical power that is rectified and later inverted for the power to the AC induction motorized wheels. 
   It is important to note that the sizes of the engines differ from one another. However, the transfer of energy between the systems is controlled for optimum efficiency and performance by way of the controller. Optimization algorithms for energy and power load profiles for typical driving conditions will serve to optimize the energy transfer and engine control by way of the controller. The AC power from each assembly is rectified and passed to DC busses that are tied together by active rectifier front ends. The common DC bus will feed four separate inverters for individual control of each of the four motorized wheels. The wheels are cast aluminum and have outer rims acting as the shorting rings for an “inside out” induction motor. 
   Once the vehicle is started, the flywheels are pre-charged and are electrically coupled to one another by the controller. One engine can charge both flywheels, one flywheel, or alternate in charging one or both flywheels. All regenerative braking is captured with an active vector control. 
   The computerized controller makes the decisions as to the choice of which of the engines are running. The electro-magnetic soft coupling is energized only during the charged cycle and charges the flywheel or flywheels only over the most efficient r.p.m. range of the engines. The computerized controller also can utilize GPS for feedback information. Front and rear sensors can be provided for detecting other vehicles so as to provide feedback signals to the computerized controller. The computerized controller can make decisions based on efficiency and rate of change of the energy transfer and the flywheel storage devices. Also, memory learning, such as day-to-day driving, can be utilized so as to maximize the efficiency of the operation of the vehicle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of the topology of the hybrid vehicle system in accordance with preferred embodiment of the present invention. 
       FIG. 2  is a diagrammatic illustration of the interaction of the flywheel system for the production of energy. 
       FIG. 3  is a schematic representation of the magnetic coupling of the internal combustion engine with the flywheel. 
       FIG. 4  is a side elevational view of the AC induction wheel as used in the hybrid vehicle system of the present invention. 
       FIG. 5  is a side view of the AC induction wheel of the present invention. 
       FIG. 6  illustrates the manner in which laminations are applied to the AC induction motor as used on the wheels of the hybrid vehicle system of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , there is shown the topology  10  of the hybrid vehicle system in accordance with the preferred embodiment of the present invention. The topology  10  includes a large internal combustion engine  12  and a smaller internal combustion engine  14 . The large internal combustion engine  12  is coupled by an electromagnetic coupling  16  to a flywheel  18 . The flywheel  18  has permanent magnets  20  extending therearound. A rectifier  22  is connected by electrical line  24  to the permanent magnets  20  associated with flywheel  18 . Rectifier  22  can be AC/DC active and DCACTUATOR  300  control. The rectifier  22  is connected by line  26  to a common DC bus  28 . 
   Similarly, the smaller internal combustion engine  14  is coupled by an electro-magnetic coupling  30  to another flywheel  32 . Permanent magnets  34  are cooperative with the flywheel  32  so as to transmit a electrical voltage along line  36  to the rectifier  38 . The rectifier  38  is also AC/DC active and DCACTUATOR  300  control. Line  40  will connect the rectifier  38  to the common DC bus  28 . 
   The computerized controller  42  is illustrated as interactive with the engines  12  and  14 , the electro-magnetic couplings  16  and  30 , the flywheels  18  and  32  and the rectifiers  22  and  38 . External sensors  44  are connected to the controller  42  so as to provide input information to the controller regarding a wide variety of variables that can affect the driving condition and condition of the hybrid vehicle system. 
   Wheels  46 ,  48 ,  50  and  52  are utilized on the vehicle of the hybrid vehicle system of the present invention. Wheels  46 ,  48 ,  50  and  52  are AC induction motorized wheels. A rectifier  52  connects the DC bus  28  to the wheel  46 . A rectifier  54  connects the DC bus  28  to the wheel  48 . A rectifier  56  connects the DC bus  28  to the wheel  50 . A rectifier  58  connects the DC bus  28  to the wheel  52 . The computerized controller  42  is cooperative with each of the rectifiers  52 ,  54 ,  56  and  58  so as to effectively control the operation of the respective wheels  46 ,  48 ,  50  and  52 . 
   The sizes of the engines  12  and  14  and the flywheels  18  and  32  will differ from one another. It is important to note that the transfer of energy between the systems associated with the large internal combustion engine  12  and the smaller internal combustion engine  14  is controlled by the controller  42 . Additionally, the power transferred from the systems to the wheels  46 ,  48 ,  50  and  52  is controlled by the controller  42  so as to optimize the efficiency and performance of the vehicle. Optimization algorithms for energy and power load profiles for typical driving conditions will serve to optimize the energy transfer and engine control by way of the controller  42 . The AC power produced by the permanent magnets  20  and  34  is rectified by the rectifiers  22  and  38 . The DC bus  28  is tied together by active rectifier front ends. The power coming from either of these systems is controlled by the controller  42  for optimized performance and efficiency based on driving condition profiles. The common DC bus  28  feeds the four inverters  52 ,  54 ,  56  and  58  for individual control of each of the respective wheels  46 ,  48 ,  50  and  52 . 
     FIG. 2  illustrates the flywheel  18  as arranged so as to be cooperative with the large internal combustion engine  12 . It can be seen that calipers  60  and  62  extend from the internal combustion engine  12  so as to be cooperative with the flywheel  18 . Ferrofluid seals  64  serve to seal the flywheel  18 . Stationary windings  66  and  68  are provided on opposite sides of the flywheel  18  and can be suitably mounted to the vehicle. The flywheel  18  is vacuum-chambered and sealed within a non-ferrous housing  70 . The calipers  60  and  62  magnetically couple the flywheel  18  to the rotating shaft of the engine  12  by way of a magnetic field coupling. The flywheel has embedded permanent magnets which provide the torque flux and are coupled with the electro-magnetic coils that are fixed onto the shaft of the engine  12 . With reference to  FIG. 1 , the permanent magnets  20  are embossed onto a side of the flywheel  18 . This magnetic coupling effect through the non-ferrous material of the housing  70  allows for the use of a non-penetrating vacuum chamber that can be permanently sealed and provides an inexpensive form of flywheel chamber. 
     FIG. 3  illustrates the electronics associated with either of the engines  12  and  14 . For the purposes of illustration, engine  14  is particularly illustrated. Each of the engines  12  and  14  are of a vertical design and meet the latest emission standards set by Federal regulatory agencies. They are vertically mounted on independent “soft” mounted engines plates. The shaft  72  of engine  14  protrudes through a mounting plate  74 . The independent flywheel assembly chambers are aligned by machined lips (not shown) at the bottom of the mounting plate  74  and are merely bolted into their respective locations so as to become properly aligned. The flywheel will also sit vertically and slide into the internal combustion engine so that the magnetic coupling creates a more balanced effect. 
   In  FIG. 3 , it can be seen that a stationary DC excitation field input  76  is connected by lines  78  to the engine  14 . This field  76  is made up of a low-power DC coupling current produced by circuit  80 . The engine shaft  72  is energized by the controller  42  and works from a lower power set of electrical coils, such as that provided by circuit  80 , so as to energize north, south, north, etc. poles which couple to the rotating flywheel permanent magnet fields through the non-ferrous material of the housing  70 . In order to achieve the electrical current (i.e. the excitation current) to the rotating pole pieces, the lower power use, stationary DC field is applied to the pole pieces  82 . The pole pieces  82  will extend around the rotating shaft  72 . A small multi-phase winding with laminations is affixed to the rotating shaft  72 . The effects of the stationary DC field flux imposed onto the rotating multi-phase winding  84  creates an alternating current which is diode-rectified with a rotating bridge rectifier plate  86 . This DC current is proportional to the amount of excitation on the stationary DC field as controlled by the controller  42 . This DC current passes through the rotating north/south pole pieces  82  so as to magnetically couple the flywheel  32  by way of the permanent magnets. The flywheel assembly  32  is now soft-coupled and de-coupled by the controller  42 . The generator end of the flywheel assembly  32  is a set of permanent magnets  34  which are electro-magnetically coupled through the non-ferrous housing  70  so as to create the necessary magnetic flux to generate the electrical power that is rectified and later inverted for the power to the wheels  46 ,  48 ,  50  and  52 , as described hereinabove. 
     FIG. 4  is a side view showing the AC induction wheel  46 . The wheels  48 ,  50  and  52  have an identical configuration. The wheel  46  has bolt holes  90  that are similar to those of typical wheel mountings. Holes  92  are provided in spaced relationship around the periphery of the wheel  46 . Holes  92  provide a space for the rotor bars to stab into. The wheel  46  is manufactured in a simple and inexpensive manner. The wheel  46  is formed of cast aluminum material. The wheel  46  has an outer rim  94  that acts as the shorting rings for an “inside out” induction motor. The wheel  46  can bolt onto standard hub configurations for typical rotation relative to the standard brake/disc and unsprung mass components. The “stator” is stationary and affixed to the chassis of the vehicle by mounting bolts. The air gap between the rotor and the stator is set upon bolting the wheel  46  to the hub. The present invention can also provide a tapered machined brace that aligns the air gap. The stator is a typical AC vector water-cooled machine, as utilized in other hybrid designs. 
     FIG. 5  is a side view of the wheel  46 . As can be seen in  FIG. 5 , bars  96  are arranged so as to “stab” into the holes  92 . The rotor bars  96  can be welded, trimmed or ground smooth. 
     FIG. 6  shows the laminations  98  that can be placed onto the bars  96  during the assembly of the rotor with the wheel  46 . The center ring of the wheel  46  is actually two halves of the rotor bars  96  in which the rotor bars  96  are simply part of the casting on one half of the wheel. Every other bar is from the opposite half and the ends of the bar protrude through the holes  92  into the other half of the wheel  46 . In this manner, strength is maintained. The pre-balanced wheel is more symmetric. The cost of this set up and tooling for mass production is the same for both halves of the wheel  46 . The laminations  98  are pre-punched and stacked into one half of the wheel  46  in the manner of standard AC inductions. The wheel is symmetrically welded. Similarly, the rotor bars  96  are welded on the protruded side on ends into the rims as shorting rings for standard AC induction rotors. 
   Once the vehicle of the present invention is started, the flywheels  18  and  32  are pre-charged. Even though these flywheels  18  and  32  are independently driven from their respective engines  12  and  14 , they are electrically coupled to one another by controller  42 . One of the engines  12  and  14  can charge both flywheels  18  and  32 , one flywheel, or alternate in charging one of the flywheels  18  and  32 . All regenerative braking is captured with active vector control. The computerized controller  42  makes the decisions as to the choice of which engine  12  or  14  is running. The electro-magnetic soft coupling is energized only during the charge cycle and charges the flywheel(s) only over the most efficient r.p.m. range of the engines  12  and  14 . Rear and front sensors, such as sensors  44 , can be used for detecting other automobiles or road vehicles so as to provide feedback signals to the controller  42 . As an example, when one is using the vehicle of the present invention to drive down a highway, a GPS feedback loop can tell the controller  42  the driving location. A power sensor and a throttle feedback sensor can inform the controller  42  of the power usage and of the driving condition of the operator. The driving condition of the operator can be based upon whether the operator has been driving steady with cruise control or manually operating the vehicle. The operator can make the control decision in which to pre-charge the larger flywheel  18  to between 6000 r.p.m. and 8000 r.p.m. This is the most efficient range for the engine  12 . However, the operator can also choose the smaller engine  14  to start and Dec. 12, 2006 stop the charging of the flywheel  18  by way of the electrical coupling from the smaller engine  14  through the active electrical coupling of the flywheels  18  and  32  by means of the DC bus  28  and by their respective inverters. 
   The active sensor  44  can provide feedback to the controller  42  such that the controller  42  will analyze the data and determine that the vehicle is quickly approaching another vehicle. When the controller  42  anticipates a passing condition through the depressing of the accelerator, the net power will be the action of the passing mode and be performed by utilizing the energy from both flywheels  18  and  32 . The controller  42  can then make the decision to start the larger engine  12  in order to recharge the flywheels  18  and  32  quickly. The controller  42  can make this decision based upon the efficiency and rate of change of the energy transfer in the flywheels  18  and  32 . Through the GPS feedback, the controller  42  can anticipate the presence of lights, exit ramps, stop lights and intersections. As a result, intelligent decisions can be calculated and anticipated. The controller  42  can thus carry out the most efficient mandates for the operation of the vehicle. 
   The present invention also facilitates the ability of memory learning, such as from day-to-day driving. Efficiency can be maximized from self-taught knowledge of anticipation of typical routes which are part of the learned memory of the controller  42 . Four wheel braking with vector control fully regenerative braking is accomplished in typical stop-and-go city driving. The efficiency of the system of the present invention is maximized in utilizing the smaller engine  14  only. The system of the present invention is very efficient by avoiding the use of CV joints, transmissions, diffentials, drive axle trains, and batteries for energy storage and costly brake losses. The engine/energy storage/power transfer is maximized by utilizing two different sized engines and by electro-magnetically coupling the stored energy devices. The engines are run in their “sweet spot”. One hundred percent regenerative braking is realized so as to make the system better than series or parallel hybrid systems. The performance/efficiency ratio due to the amount of stored energy and means of transfer utilization of the two systems makes for a high performance and maximum efficiency system. 
   The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.