Abstract:
A piezoelectric generator comprises a centrifugal force sampling mechanism being carried around a central axis. The direction of the centrifugal forces, do to rotational control, acting on the sampling mechanism is reversed periodically to alternately apply and relieve distortion on two adjacent piezoelectric elements. The slug shaped piezoelectric elements produce high voltage charges while undergoing little change in shape or length in response to high-energy impulses.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the generation of electrical energy, and particularly to a piezoelectric electric generator using a centrifugal impulse to mechanically distort the piezoelectric elements. 
     Mechanical distortions of piezoelectric materials cause displacements of electrical charges within the materials. The forces needed to cause this distortion must be alternately applied and relieved for generation of electrical energy. The energy required to alternately apply and relieve the mechanical distortions on the piezoelectric materials is generally grater than the electrical energy output of the generator. The present invention addresses this problem. 
     SUMMARY OF THE INVENTION 
     In accordance with the first aspect of the invention, a group of elements (hereinafter referred to as the impulse assembly) comprising two preloaded piezoelectric elements mounted centric to a pair of weighted lever arms are rotated around a central axis. The lever arms are mounted at opposite ends of the impulse assembly with the weighted end of each lever arm directed outward along the same vertical plane. The piezoelectric elements are preloaded at equal and opposite position from the pivot point of each lever arm, locking the lever arms in position. This arrangement allows unloading of one piezoelectric element and simultaneous loading of the adjacent piezoelectric element. This invention has the advantage of delivering high impact, high frequency impulses to the piezoelectric elements, independent of the energy needed to drive the drive shaft. 
     Each piezoelectric element is a cylindrical slug clamped between two opposing lever arms. As the torque forces are applied to each end of the slug, the piezoelectric element is distorted and shortens 3 to 4 micro inches per 100 psi. This small movement in the position of the lever arms has a negligible effect on the balance and inertia of the generator. 
     In accordance with the final aspect of the invention, one or more impulse assemblies may be used to form a single generator output. The impulse assemblies being matched must be placed around the central axis to form a precision balanced flywheel assembly. Once the generator is at maximum operating speed. The primary energy needed to drive the drive shaft, will be the generators own inertia. Overloading the generator output does not create feedback or loading of the drive shaft. Only a small amount of input energy is needed to overcome the inherent resistance of the generator. Accordingly, the primary advantage of the invention is its ability to generate enough energy to operate itself and other electrical devices simultaneously and indefinitely. Further objects and advantages of particular aspects of my invention will become apparent from a consideration of the drawings and ensuing description thereof. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Some of the drawing figures are not necessarily to scale. 
     FIG. 1 is an isometric view of the centrifugal impulse piezoelectric generator in accordance with this invention, with duplicated structures broken away and some structures partly in section; 
     FIG. 2 is an isometric view of the impulse assembly with top half of view partly in section; 
     FIG. 3 is an isometric view of the impulse assembly&#39;s base shown in isolation and partly in section; 
     FIG. 4 is a sectional view of the piezoelectric element, it&#39;s housing and the elements related to the loading and preloading of the piezoelectric element as shown in FIG. 2 taken along line  4 — 4  of FIG. 2; 
     FIG. 5 is an isometric view of the central wheel with an offset shaft inserted in one bearing position and another bearing position partly in section; 
     FIG. 6 is an isometric view of the offset wheel with two offset shafts inserted and one bearing position partly in section, mounted on the generator mount. The view includes the generator mount partly in section with the drive shaft and the drive wheel in position. 
    
    
     DESCRIPTION OF THE INVENTION 
     Refer to FIG. 1 as an overview of the following descriptions. 
     With reference to FIG. 6, all elements are supported by the generator mount  23 , which has a hub  23   h  at the rear to support the rear drive shaft bearing  34 . The two drive shaft bearings  34  and  31  define a shaft central axis  60 . The front of the generator mount  23  has a circular lip  231  with a diameter equal to the inside diameter of the offset wheel bearing  25  and a rise equal to 20% the thickness of bearing  25 . The axis  61  of the circular lip  231  is sufficiently offset along a horizontal plane from the central axis  60  to allow the drive shaft  27  to rotate around the central axis  60  without making contact with the inside diameter of the offset wheel bearing  25 . This offset will hereinafter be referred to as the “alignment offset”. 
     The offset wheel bearing  25  is fitted onto the circular lip  231  and held in place by the bearing cap  30 . 
     The top section of bearing cap  30  has a diameter slightly greater than the inside diameter of the offset wheel bearing  25  and the bottom section  301  has a diameter equal to that of the circular lip  231 . In addition, a drive shaft bearing  31  is mounted at a position centered on the central axis  60 . Two screws  29  are used to hold the bearing cap  30  and the drive shaft bearing  31  in position. 
     The drive shaft  27  extends through and axially beyond drive shaft bearings  34  and  31 . The front end of the drive shaft  27  has an indentation  27   i.  A drive wheel  32  is machine pressed onto the rear end  27   r  of the drive shaft  27 . Two retaining rings  28  restrain linear motion along the central axis  60  by drive shaft  27 . The retaining rings  28  are inserted into groves  50  on the drive shaft  27  located adjacent to the front of drive shaft bearing  31  and at the rear of drive shaft bearing  34 . 
     The offset wheel  26  is fitted onto the outer race of the offset wheel bearing  25 . The offset wheel  26  comprises an inner lip  261  and three spokes  24  equally spaced and projecting outward. A bearing  18  is machine pressed into the outermost end of each spoke  24 , and each bearing  18  is at an equal distance (hereinafter referred to as the impulse radius) from the offset axis  61 . 
     The offset shaft assembly  17  comprises a front shaft  17   f  and a rear shaft  17   r.  The axes  63  of the front shaft  17   f  and the axis  62  of the rear shaft  17   r  are offset along a horizontal plane a distance equal to the “alignment offset”. The offset shaft assembly  17  does not rotate around either axis  62  or  63 . The forward end of shaft  17   f  has an indentation  17   i  used to secure impulse means. Two of the three offset shaft assemblies  17  required in this invention are shown with their rear shafts  17   r  inserted fully into two bearings  18 . 
     With reference to FIG. 5, the central wheel  21  comprises a hub extension  21   h;  a setscrew  22  and three spokes  19 . The hub extension  21   h  increases the mounting stability of the central wheel  21 . The three spokes  19  are equally spaced and projecting outward. A bearing  18  is machine pressed into the outermost end of each spoke  19 . The distance from each bearing  18  to the central wheel&#39;s axis  20  is equal to the “impulse radius”. One of three offset shaft assemblies  17  required in this invention is shown with its front shaft  17   f  extended through and axially beyond a bearing  18 . 
     With reference to FIGS. 5 and 6, the drive shaft  27  extends axially through the central wheel  21  and its hub extension  21   h  to align the indentation  27   i  with the setscrew  22 . With the rear shaft  17   r  and the front shaft  17   f  of each offset shaft assembly  17  positioned as previously defined, the setscrew  22  is tightened against the indentation  27   i  to secure the position of the central wheel  21 . 
     With reference to FIG. 3, the base  10  of each impulse assembly comprises a hub  10   h,  a setscrew  9  and two bearings  11  at opposite ends of the base  10 . The two bearings  11  and the base axis  10   a  are in the same vertical plane with each bearing  11  equally spaced from the base axis  10   a.  The inside diameter  12  of the hub  10   h  extends along axis  10   a  and a short distance pass the setscrew  9 . The two threaded holds  13  are used to secure the piezoelectric housing  7  as shown in FIG.  2 . 
     With reference to FIG. 3 and 5, the front shaft  17   f  is inserted fully into the base  10  along axis  10   a  to align the indentation  17   i  with the setscrew  9 . The setscrew  9  is tightened against the indentation  17   i  to secure the position of the impulse assembly base  10 . 
     With reference to FIG. 2, a complete impulse assembly is shown with its piezoelectric housing  7  mounted to a base  10  using two screws  13   a.  A short shaft  1   c  (hereinafter referred to as a pivot point) extends end to end through bearings  11 . Each lever arm  1  has two short lever arm extensions  1   a  and  1   b  at right angles to the lever arm  1  and positioned at its pivot point  1   c.  A hex head screw  15  is used to mount a weight  16  to the end opposite the pivot point  1   c  of each lever arm  1 . Each pivot point  1   c  is secured with a flat head bolt  14  opposite the lever arm  1 . The weighted end of each lever arm  1  is directed away from the piezoelectric housing  7 , with each lever arm extension  1   a  and  1   b  making contact with an individual preload screw  4 . The housing  7  contains a pair of piezoelectric elements  5  with preloading means at either end of each. Equal preloading of the piezoelectric elements  5 , places equal pressure on the lever arm extensions  1   a  and  1   b,  locking each lever arm  1  into position. 
     With reference to FIG. 4, each piezoelectric element  5  has preloading means at each end comprising a piston  3  in full contact with the piezoelectric element  5  and extending to the end of the housing  7 , a preload screw  4  and a locking nut  2 . Preloading causes the piezoelectric element  5  to distort and shorten. The preload screw  4  is adjusted to remain in contact with the lever arm extension  1   a  (or  1   b  as shown in FIG. 2) when unloading of the piezoelectric element  5  occurs. The locking nut  2  retains the position of the preload screw  4 . Each piezoelectric element  5  has an electrode  6  at each end extending through a hold  8  in the housing  7  from which electrical energy can be obtained. 
     OPERATION OF THE INVENTION 
     With reference to FIG. 1, the drive wheel  32  is used to transfer energy to the drive shaft  27 . The type of drive wheel  32  is determined by the coupling means required (i.e., gear, chain, drive belt . . . etc.), to connect the drive wheel  32  to the input energy source. The central wheel  21  is driven directly by the drive shaft  27 . 
     The central wheel  21 , by means of the offset shaft assemblies  17 , drives the offset wheel  26  around the offset axis  61  (as shown in FIG.  6 ). The offset wheel  26  rotates freely on bearing  25 . This arrangement restrains the offset shaft assemblies  17  from rotating around their own axes and establishes rotational control of the impulse assemblies. Accordingly the vertical orientation of the impulse assemblies remain fixed as they rotate around the drive shaft  27 . 
     Electrical energy is generated when the two lever arms  1 , mounted at opposite ends of the impulse assembly base  10 , develop equal and opposite torque rotation at the pivot points  1   c.  The opposing torque rotations serve two important functions. First, the opposing forces are directed onto opposite ends of a piezoelectric element  5  through a piston  3 , a preload screw  4  and a lever arm extension  1   a  or  1   b.  The applied forces cause the piezoelectric element  5  to distort and shorten, creating an electric charge across its electrodes  6 . Secondly, the equal but opposite rotational energies exerted on the impulse base  10  cancel out, greatly reducing or eliminating any torque loading of the coupling, (offset shaft assembly  17 ) between the central wheel  21  and the offset wheel  26 . 
     The position of the piezoelectric elements  5  and their preloading elements is maintained by the housing  7 . The mass of the weight  16 , the length of the lever arm  1 , the impulse radius and the rotational rate of the drive wheel  32  determine the amount of force applied to the piezoelectric elements  5 . 
     The centrifugal forces acting on the weight  16  are constant, however the angle at which the forces are applied to the weight  16  with respect to the lever arm  1  result in a periodic sampling of the forces, generating a centrifugal impulse. For each 360-degree rotation wherein the axis of the impulse assembly and the axis of the drive shaft  27  intersect the same vertical plane at 0 and 180 degrees, the centrifugal forces will be parallel to the lever arms  1 , generating negligible torque at the pivot points  1   c.  When the axis of the impulse assembly and the axis of the drive shaft  27  intersect the same horizontal plane at 90 and 270 degrees, the centrifugal forces will be at right angles to the lever arms  1 , generating torque at the pivot points  1   c.  At 0 and 180 degrees the forces acting on the piezoelectric elements  5  are equal and supplied by the preloading elements only. At 90 degrees peak forces are applied to one piezoelectric element  5  and negligible forces on the adjacent piezoelectric element  5 . At 270 degrees the application of forces to the piezoelectric elements  5  are reversed. Accordingly each piezoelectric element  5  receives one complete impulse per 360 degrees of rotation at 180 degrees out of phase with its adjacent element. 
     While the above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof. Many other variations are possible, for example; the piezoelectric elements can be mounted directly adjacent to the mass on which the centrifugal forces are applied. It is also possible to construct an impulse assembly with a flexible weighted piezoelectric element. The shaft on which the impulse assembly is mounted can be restrained from rotating around its own axis by fitting it with a gear and coupling it to a gear of equal size mounted and fixed at the central axis. Gearing of unequal size can be used to change to rotation of the impulse assembly around its own axis and thus change the centrifugal sampling rate. The energy from the impulse assemblies can be mechanically transmitted to stationary piezoelectric elements. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.