DESCRIPTION of the PREFERRED and ALTERNATIVE EMBODIMENTS
With reference to the drawings, there is generally shown in FIG. 1 a lawn rake 100 including a handle 120 and a cross head assembly 130. Lawn rake 100 s performs a conventional function of raking leaves and lawn debris, as well as an additional function of pushing piles of accumulated leaves and lawn debris. Cross head assembly 130 includes a transverse cross arm 145, a truncated tee 150, and an array 160 of tines 170. Array 160 shows tines 170 substantially coplanar, arranged in side-by-side, parallel spacing.
In FIG. 1A a cross head 140 is shown comprising cross arm 145 with truncated tee 150 mounted thereon. Truncated tee 150 includes a socket portion 154, and a barrel portion 155 having an internal cylindrical surface 156. Truncated tee 150 slides on to an end of cross arm 145. Truncated tee 150 engages cross arm 145 by means of a frictional fit acting at the contact surface areas of internal cylindrical surface 156 of tee 150 and the external cylindrical surface of cross arm 145. Truncated tee 150 is medially located on cross arm 145 with socket portion 154 for receiving handle 120. Truncated tee 150 is permanently secured to cross arm 145 by one or more fasteners 132 which may be one or more rivets, screws, bolts, pins, or any other appropriate fastener. Only one fastener is shown in FIGS. 1 and 1A and its location is representative of many possible locations around barrel portion 155 of truncated tee 150.
Handle 120 may be an elongated tubular member or an elongated solid rod composed of any material established by the prior art as suitable for the handle of a lawn rake. In particular, handle 120 may be composed of a thermoplastic material, or specifically the thermoplastic material polyvinylchloride. Handle 120 may be equipped with an end cap that is attached frictionally, with glue, or with a fastener such as a rivet.
Handle 120 may connect to socket portion 154 of truncated tee 150 by any number of means established in the prior art. As shown in FIG. 1, an adaptor 122 is attached to an end of handle 120. Adaptor 122 may be a thermoplastic fitting having an internal socket portion for engaging end of handle 120 by a fricitional fit, permanently secured by one or more fasteners 124 which may be one or more rivets, screws, bolts, pins, or any other appropriate fastener. Only one fastener is shown in FIG. 1 and its location is representative of many possible locations around adaptor 122. Adaptor 12 has external threads for threadable connection to socket portion 154 of truncated tee 150, it being understood that socket portion 154 has matching internal threads to receive adaptor 122. Socket portion 154 may also threadably receive handle 120 directly, it being understood that external threads are provided on the end of handle 120, and matching internal threads are provided in socket portion 154, for the threadable connection. Socket portion 154 may also insertably receive handle 120 by either a permanent connection or a releasable connection. For a permanent connection, socket portion 154 receives handle 120 by a frictional fit, and is secured by a fastener such as a bolt and nut, or a locking pin, or secured by one or more rivets. For a releasable connection, socket portion 154 receives handle 120 by a slip fit, secured by a fastener such as a bolt and nut, or a locking pin.
In FIG. 2, lawn rake 100 is shown in side elevation, further illustrating the generally coplanar arrangement of tines 170 to form array 160. An obtuse angle A is shown subtending handle 120 and array 160. Angle A provides the benefit of increasing the size of the cavity that forms between array 160 and an expansive surface such as the ground or a lawn. For efficient performance of lawn rake 100 in raking action, angle A ranges from approximately 130.degree. to 170.degree.. An angle B subtends array 160 and the expansive surface. An angle C subtends the extension of the centerline of handle 120 and the expansive surface. Due to the geometry established by obtuse angle A, angle B is necessarily larger than angle C, The leaf and lawn debris containing cavity of lawn rake 100, defined by angle B, is thus larger than the cavity obtained if array 160 is substantially coplanar with handle 120, forming a cavity defined by angle C. Of course, angle B may equal angle C if so desired, in which case cross head assembly 130 is substantially coplanar with handle 120. A direction of movement M denotes the movement of lawn rake 100 in a conventional manner for raking leaves and lawn debris.
In addition, leaves and lawn debris have an angle of repose since the leaves and lawn debris constitute a loose, free standing material. As a result of the configuration of cross head assembly 130 created by angle A, and angle B, array 160 does not tend to ride up and over an accumulated pile of leaves and lawn debris, as is the case with a fan shaped rake head that is substantially coplanar with the handle. Instead array 160 is able to compress and cut into an accumulated pile of leaves and lawn debris. Cross head assembly 130 is then able to penetrate the pile of leaves and lawn debris and provide further forward urgement to the leaves and lawn debris. Obtuse angle A is obtainable from the unique structure of cross head assembly 130 as described below. The value of angle A is not limited by any structural considerations of lawn rake 100. Angle A is solely determined by the most efficient and productive raking action that can be accomplished with lawn rake 100.
Cross head assembly 130 is generally shown in FIG. 3, further showing the medial location of truncated tee 150 on cross arm 145. Also shown is the parallel side-by-side spacing of tines 170. For cross head assembly 130, the width of truncated tee 150 is a value such that uniform parallel side-by-side spacing of tines 170 can be accomplished. A tip spacing t is selectable based on the raking efficiency desired for lawn rake 100. Parallel side-by-side spacing of tines 170 generally results in tip spacing t of about 7/8 of an inch center-to-center for efficient performance of lawn rake 100. Tines 170 include an end tine 170a and an end tine 170x. Other tip spacings may be selectable to vary the performance of lawn rake 100.
A top view of cross head assembly 130 taken in the direction D of FIG. 2, is shown in FIG. 4. Cross arm 145 is shown as a transverse member with truncated tee 150 including socket portion 154. Cross arm 145 comprises an elongated tubular member having a plurality of pairs 162 of diametrically opposed circular apertures 164 arranged in a colinear manner. Only one aperture of each pair 162 is shown in FIG. 4. For ease of illustration, tines 170 are only shown engaging some of apertures 164. Insertion of tines 170 through apertures 164 results in array 160 being substantially coplanar. Cross arm 145 is composed of tubular material that provides uniform structural strength to cross head assembly 130 in all directions for resisting bending loads applied to cross arm 145. Uniform structural strength is achieved by the radial symmetry of cross arm 145 having a closed cross section everywhere except at apertures. The strength of cross arm 145 is diminished minimally by the presence of apertures 164. Cross arm 145 also provides anchoring and support for tines 170.
The tubular material may be a thermoplastic material. The thermoplastic material may be fiber reinforced or fiberglass reinforced. In particular, the thermoplastic material may be polyvinylchloride. The polyvinylchloride material may be fiber reinforced or fiberglass reinforced. More particularly, the polyvinylchloride material may be the commonly available, commercially mass produced, polyvinylvhloride plumbing pipe. Alternatively, the tubular material may be a metal such as steel or aluminum, or the tubular material may be fiberglass. The width of cross arm 145, and thus of cross head assembly 130, is limited only by the requisite rigidity of cross arm 145 to effectively perform raking action, by the weight of cross head assembly 130, and by the ability of the user to manipulate lawn rake 100.
FIG. 5 is a sectional view through cross arm 145 at apertures 164. A top aperture 164a and a bottom aperture 164b comprise pair 162 of apertures 164. Apertures 164 have a diameter larger than the diameter of times 170, for ease of insertion, for ease of removal, and for the releasability of tines 170, as will be described further. A centerline CL passes through the centers of apertures 164a and 164b. With lawn rake 100 in a leaf and lawn debris raking disposition, centerline CL generally falls along angle B in FIG. 2 that array 160 develops with the ground. The relative diameters of tines 170 and apertures 164 can be changed to vary the benefits of the present invention. Apertures 164 loosely position tines 170 on cross arm 145.
Elements of tine 170 are illustrated in FIG. 6. Tine 170 comprises a single piece of resilient material and includes a stem 172, and a looped bend 178 for engaging cross arm 145 by snap action. Looped bend 178 terminates in the tine end 180. Looped bend 178 may take the shape of an arc segment of a circle, with looped bend 178 having an inside diameter approximating the outside diameter of cross arm 145. Should the inside diameter of looped bend 178 be slightly smaller than the outside diameter of cross arm 145, looped bind 178 may contact cross arm 145 only at the point of tine end 180. Stem 172 further includes a bend 174. Tine 170 terminates in a ground engaging tip 176. With tine 170 positioned on cross arm 145, tip 176 is generally normal to the expansive surface upon which lawn rake 100 operates. Tine end 180 is generally perpendicular to the curvature of looped bind 178. An end gap e is a predetermined distance from tine end 180 to the nearest point of stem 172. An angle F is subtended by tine end 180 and stem 172.
Tine 170 has a solid, circular cross section. The diameter of tine 170 is less than the diameter of circular apertures 164. Tine 170 may be composed of a thermoplastic material. In particular, tine 170 may be injection molded from a thermoplastic material, which may specifically be polyvinylchloride. As an alternative, tine 170 may be formed from polyvinylchloride rod by heating and bending the rod to the appropriate configuration as shown in FIG. 6. Bend 174 may alternatively be mechanically bent without heat to form the appropriate predetermined angle. The diameter of the circular cross-section of tine 170 is related to the length of tine 170, and the physical properties of the material of which time 170 is composed. Polyvinylchloride rod having a diameter of approximately 3/16 inch provides efficient leaf and lawn debris raking action while minimizing breakage. Other diameters of tines 170 may be appropriate based on the length of tines 170 and the material of composition of tines 170. Tines 170 may alternatively be composed of a spring steel material having appropriate physical properties of strength and elasticity. The spring steel may have a cross section that is circular or that is flat and rectangular. As other alternatives, tines 170 may be made from fiberglass, fiber reinforced thermoplastic, or fiberglass reinforced thermoplastic, and have a circular cross-section or a flat, rectangular cross-section.
Apertures 164 may have a diameter of approximately 1/4 inch in consideration of a diameter of tines 170 which is approximately 3/16 of an inch. Alternatively, top apertures 164a and bottom apertures 164b, may have diameters that differ. Apertures 164 may have other diameters, depending on the diameter of tines 170.
In FIG. 7 tine 170 is shown mounted on cross arm 145. The position of tine 170 within apertures 164 illustrates the larger diameter of apertures 164 compared to the diameter of tine 170. In FIG. 7A an enlarged view of looped bend 178 shows engagement with cross arm 145. A clearance c is the distance s between cross arm 145 and the inside diameter of looped bend 178. Clearance c is measured when stem 172 is in contact with that point of the circumference of both apertures 164a and 164b that produces the maximum value of clearance c. The force required to install or remove tine 170 from cross arm 145 is related to end gap e, clearance c, the stiffness of looped bend 178, and the difference in diameters of apertures 164 and tine 170. End gap e is a measure of the degree of mechanical anchorage of looped bend 178 on cross arm 145. Clearance c is a measure of the looseness of looped bend 178 on cross arm 145 and is necessarily related to the advantages obtained from apertures 164 having a larger diameter than tines 170. The effect of oversized apertures 164 operating in conjunction with looped bend 178 is to trap tine 170 loosely in position on cross arm 145. Tine 170 is thus attached to cross arm 145 in a non-rigid, non-fixed, manner, absent a sufficient force during raking action to cause release of tine 170 from cross arm 145, as will be explained later.
Clearance c may be as much as approximately one-half the difference in diameters of apertures 164 stem and 172. Clearance c may also be minimized such that looped bend 178 just barely touches cross arm 145 along the internal arc of looped bend 178. In the case of looped bend just touching cross arm 145, the resilience of the material of which tines 170 are made, does not allow frictional resistance to develop between looped bend 178 and cross arm 145 because of insufficient stiffness of looped bend 178. In addition, any upward force on ground engaging tip 176 tends to open up looped bend 178 to disengage it from cross arm 145 so that any contact frictional resistance is intentionally defeated. The benefits of this characteristic are illustrated and explained later.
FIG. 8 is a bottom view of cross head assembly 130 taken in the direction U of FIG. 2. A tine 170k is shown with bend 174 and tip 176 removed for illustration only. The circular cross-section of stem 172 is thus shown positioned within bottom aperture 164b with a resulting eccentric annular space around stem 172 where it passes through bottom aperture 164b. A similar eccentric annular space would be situated around stem 172 where it passes through top aperture 164a. Stem 172 generally is shown eccentric within apertures 164 due to the inherent looseness and play between tines 170 and apertures 164, which provide unique aspects of the present invention in terms of installation, removability, releasability, and energy absorption of tines 170. A uniform annular clearance around stem 172, or an eccentricity of stem 172 within apertures 164 that places stem 172 in contact with any part of the circumference of apertures 164a, 164b,or both, does not alter the benefits of the present invention. End gap e between tine end 180 and stem 172 is also shown in FIG. 8, as is the relationship of bend 178 of a tine 170c as it engages cross arm 145 from above and curls toward the bottom of cross arm 145.
In FIG. 9 there is shown a perspective view of truncated tee 150 by itself, in the approximate orientation it would take as mounted on cross arm 145. Truncated tee 150 is shown including its component elements barrel portion 155 having internal cylindrical surface 156, and socket portion 154. The width of barrel portion 155 approximates the outside diameter of socket portion 154. Tee 150 may be injection molded from a thermoplastic material. Tee 150 may particularly be molded from the thermoplastic material polyvinylchloride. Tee 150 may also be produced by cutting off the arms of the T-shape of plumbing fittings generally referred to as tees which may already be made from a thermoplastic material such as polyvinylchloride. These same plumbing tees may also require reaming to provide an internal diameter that enables tee 150 to slide onto cross arm 145 with a frictional fit.
Orthogonal views of tee 150 further illustrating its component elements are shown in FIGS. 10A-D. Tee 150 is shown in: front elevation in FIG. 10A, side elevation in FIG. 10B, top plan view in FIG. 10C, and bottom plan view in FIG. 10D. In FIG. 10C, internal cylindrical surface 156 is seen looking down socket portion 154, demonstrating the connecting internal space of socket portion 154 and barrel portion 155. FIG. 10E shows a sectional view of tee 150 taken from FIG. 10A, illustrating the internal threads of socket portion 154 to threadably receive handle 120. The frictional mounting of tee 150 on cross arm 145 is shown in FIG. 10F, illustrated by the line of contact shared by internal cylindrical surface 156 and the external cylindrical surface of cross arm 145. Also shown in FIG. 10F is a single fastener 132a consisting of a screw, located in a representative position different from fastener 132 in FIGS. 1 and 1A.
A vertical section through an alternative truncated tee 151 is shown in FIG. 11. Tee 151 differs from tee 150 by a reinforcing portion 157 that separates the internal space of socket portion 154 and the internal space of barrel portion 155. Reinforcing portion 157 provides additional strength and rigidity to tee 151. Tee 151 may be injection molded from a thermoplastic material, which may particularly be polyvinylchloride.
FIGS. 12A and 12B illustrate the installation of tine 170 by snapping tine 170 into place on cross arm 145. In FIG, 12A the application of finger force is all that is required to push tine end 180 up and over cross arm 145. As this is done, bend 178 opens up, storing elastic strain energy in bend 178. Once tine end 180 reaches the point of cross arm 145 where bend 178 opens the widest, as shown in FIG. 12B, the resilient elasticity of the material of which tine 170 is composed, causes release of the elastic strain energy, further causing bend 178 to snap into place around cross arm 145. During application of finger force, angle F allows tine end 180 to ramp up cross arm 145 by a wedging action, during installation of tine 170.
In a similar manner, as shown in FIG. 12C, once tine 170 is positioned on cross arm 145, finger force can be applied to tine end 180 to cause bend 178 to open up and be released from cross arm 145 for the purpose of removing tine 170. This action can be utilized to remove a particular tine and reposition it at another location on cross arm 145. For example, if an intermediately located tine of array 160 is broken, end tine 170a or 170x can be removed and relocated to the position of the broken tine. This allows raking action to quickly be continued without obtaining a replacement tine, which would otherwise be required to maintain uniformity of raking. Without the repositioned or replacement tine, a trail of leaves or lawn debris remains on the ground in the area of array 160 left vacant where the original tine was located, thus requiring additional raking effort.
In FIGS. 13A-13F the releasable operation of tine 170 during raking action is demonstrated along with the retractability and retainability of tine 170, and the energy absorbing ability of tine 170. In the same way that finger force applied to tine end 180 causes release of bend 178 from engagement with cross arm 145, application of an upwardly force on tip 176 can have the same effect. Such application of an upwardly force can occur during raking action if lawn rake 100 is placed in operation on an expansive surface that has a protruding object such as a rock or root. A protruding object is a common cause for distortion or breakage of tines on lawn rakes. If bend 178 engaged cross arm 145 fixedly, then application of an upwardly force on tip 176 can cause tine 170 to bend and break, particularly in the case of a plastic tine.
Instead, the releasability of bend 178, previously described with regard to intentional removal of tines 170 in FIG. 12C, allows the applied force to be transmitted along stem 172 without breaking tine 170. The transmitted force then acts upwardly on bend 178 where it meets stem 172, causing bend 178 to open and disengage from cross arm 145. The magnitude of the force required to release tine 170 from cross arm 145 depends on end gap e, clearance c, and the stiffness of bend 178. These parameters are selected, predetermined values such that the properties of the present invention are beneficially obtained. The object is to control the looseness of tine 170 on cross arm 145 such that tine 170 remains attached to cross arm 145 during normal raking action, but absorbs energy and releases from cross arm 145 upon application of predetermined loading conditions on tip 176 that might otherwise cause tine 170 to break.
The position of tine 170 instantaneously after application of an upwardly force on tip on tip 180 is shown in FIG. 13A. The application of the upwardly force may cause sudden release of tine 170 such that stem 172 is propelled through apertures 164 with tine 170 attempting to shoot out of cross arm 145. The physical configuration of tine 170 at bend 174 prevents tine 170 from completely disengaging from cross arm 145. Thus, tine 170 is retained on cross arm 145 in a released position, as indicated in FIG. 13A. Tine 170 can be reengaged on cross arm 145 by application of finger force, as earlier demonstrated in FIGS. 12A and 12B. Tine 170 has consequently avoided breakage that might otherwise occur as a result of impacting a protruding object.
Once tine 170 reaches the released position of FIG. 13A, at least one more force is required to completely remove tine 170 from cross arm 145. The diameter of apertures 164 has a predetermined value, as previously explained, such that tine 170 can displace upwards upon application of finger force on tine end 180, or upon application of an upwardly force on tip 176. The magnitude or duration, or both, of a force on tip 176 to cause complete disengagement of tine 170 from cross arm 145 is necessarily larger than the magnitude or duration, or both, of a force on tip 176 required to merely release bend 178 from engagement with cross arm 145.
With tine 170 in the position of FIG. 13A, removal of tine 170 from cross arm 145 first requires movement of bend 174 to the vicinity of bottom aperture 164b, as shown in FIG. 13B. Stem 172 proximate bend 174 must deform in order for bend 174 to pass first through bottom aperture 164b and then through top aperture 164a. The larger diameter of apertures 164, compared to the diameter of tine 170, together with the elastic properties of tine 170, allow the deformation to take place, and further allows the deformed configuration of stem 172 and bend 174 to pass through apertures 164. The deformation of stem 172 has the effect of providing sufficient temporary alignment to tine 170 proximate bend 174 such that oversized apertures 164 eventually allow tine 170 to completely disengage from cross arm 145.
The force required to completely remove tine 170 from cross arm 145 may be applied in one quick uniform motion. The configuration of tine 170 with relation to cross arm 145 as shown in FIG. 13F would then be obtained. However, application of the force can be further broke down into a series of discrete steps to further demonstrate the unique attributes of tine 170. Deformation of stem 172 in FIG. 13C is shown occurring above bend 174. A similar benefit accrues to the present invention if deformation takes place below bend 174.
Upon application of an upwardly force on tip 176 that first, causes bend 178 to disengage from cross arm 145 and second, causes tine 170 to shoot upward, bend 174 prevents tine 170 from navigating through apertures 164. The upwardly force is only an instantaneous force and in most circumstances is dissipated once bend 174 reaches aperture 164b. In order for tine 170 to completely disengage from cross arm 145, a second upward force acting on tine 170 is required to deform stem 172 proximate bend 174 so that bend 174 can pass through bottom aperture 164b, as shown in FIG. 13C.
Once bend 174 navigates through bottom aperture 164b, the deformation of stem 172 relaxes and tine 170 is retained in this position, with bend 174 trapped within cross arm 145 as shown in FIG. 13D. In some cases an upward force on tip 176 may in fact be of sufficient magnitude to cause tine 170 to immediately reach the position of FIG. 13D. This position is an equilibrium position and demonstrates retractibility of tine 170. A third upward force is then required to deform stem 172 proximate bend 174 once again, as shown in FIG. 13E, so that bend 174 can pass through top aperture 164a. The deformation that takes place for bend 174 to pass through top aperture 164a is similar to the deformation that takes place for bend 174 to pass through bottom aperture 164b. After bend 174 passes through top aperture 164a, as in FIG. 13F, tine 170 is freely removable from cross arm 145.
Reinsertion of tine 170 through apertures 164 of the same tine position, or any other tine position, requires application of at least one continuous downward force along stem 172 of tine 170. Alternatively, two successive downward forces may be exerted along stem 172, to urge passage of bend 174 through top aperture 164a and then through bottom aperture 164b, respectively. The process of inserting tine 170 through pair 162 of apertures 164 would follow FIGS. 13A-F in reverse order, starting with FIG. 13F. If capturing of bend 174 within cross arm 145 is not desired, apertures 164 can be appropriately sized so that stem 172 does not undergo deformation during insertion and removal of tine 170. Only the force from the fingers of a user's hand is required to install tines 170 on cross arm 145, or to manually release and remove tines 170 from cross arm 145.
FIGS. 14A and B, FIG. 14C, and FIGS. 15A and B, together show unique aspects of the present invention that reside in tines 170 operating in conjunction with apertures 164 of cross arm 145. FIGS. 14A and B illustrate front-to-back freedom of movement of tines 170 on cross arm 145 as a result of the larger diameter of apertures 164 compared to the diameter of tines 170. Clearance c allows stem 172 of tine 170 to be positioned within apertures 164 such that stem 172 in an ideal situation is centered within apertures 164. More likely stem 172 is positioned such that stem 172 is in contact with the circumference of aperture 164a, or aperture 164b, or both.
In FIGS. 14A and B, centerline CL only aligns with the centerline of tine 170 when stem 172 is concentric with apertures 164. Instead as actually shown in FIGS. 14A and B, tine 170 with clearance c may assume a position where the opposite sides of stem 172 are in contact with the circumference of apertures 164a and 164b, respectively. The force of gravity keeps tine 170 in the position of FIG. 14B before tine 170 is placed in contact with an expansive surface. When tine 170 is placed in contact with an expansive surface, tine 170 assumes the position of FIG. 14A, due to the downward acting weight of lawn rake 100. An arc of displacement DD denotes the angle subtended by the centerline of stem 172 with centerline CL, when tine 170 reaches an upper limit of movement due to stem 172 contacting the circumferences of apertures 164, as shown in FIG. 14A.
An arc of displacement DD' denotes the angle subtended by the centerline of stem 172 with centerline CL, when tine 170 reaches a lower limit of movement due to stem 172 contacting the circumferences of apertures 164, as shown in FIG. 14B. At either limit of movement it is assumed there is no bending of tine 170. Arc of displacements DD and DD' may be considered to be equal. Movement of tine 170 from the position of FIG. 14A to the position of FIG. 14B demonstrates engageable operation of looped bend 178 around cross arm 145, in conjunction with movement of stem 172 loosely positioned within apertures 164, to provide pivotal movement of tine 170 within a vertical plane.
FIG. 14C shows side-to-side freedom of movement of a tine 170w mounted on cross arm 145. Apertures 164 oversized with respect to stem 172, and clearance c between looped bend 178 and cross arm 145, allow stem 172 to rotate on its axis and pivot laterally. A position P and a position P' denote respectively, the left and right limits of movement of tine 170w such that bend 178 contacts cross arm 145. Movement of tine 170w is typical of movement of any tine 170. In moving from position P to position P', tine 170w can rotate within a horizontal arc H. This horizontal rotation is further demonstration of the pivotal mounting of tines 170 on cross arm 145. Previous figures have shown bend 178 in an idealized position with bend 178 oriented perpendicular to cross arm 145. In actuality, clearance c and apertures 164 permit bend 178 to pivot back and forth around the axis of stem 172 during raking action as loading conditions require. The pivoting represents a second freedom of movement of tines 170, in addition to the freedom of movement within the plane of tine 170 demonstrated in FIGS. 14A and 14B. The combined freedoms of movement shown in FIGS. 14A and B, and FIG. 14C, illustrate the ability of tines 170 to absorb unbalanced forces by causing tines 170 to shift position, unless the forces are of such magnitude to cause one or more tines 170 to release from cross arm 145.
Tines 170 possess additional freedom of movement to rock back and forth in the plane of array 160. Consequently, it has been demonstrated that tines 170 possess the capability of freedom of movement in three perpendicular planes. Thus, the present invention introduces and controls looseness between tines 170 and cross arm 145. Freedom of movement of tines 170 is promoted by means of clearance c and/or oversized apertures 164, assisted by the flexible resilience of the material composing tine 170, thereby minimizing stresses. These characteristics in combination with end gap e, then control the upward force required to release tine 170 from across arm 145.
The advantage of the freedom of movement of stem 172 within apertures 164 becomes further apparent in conjunction with the explanation of FIGS. 15A and B. These two figures illustrate the configurations of tine 170 when undergoing deflection due to the application of loads during raking action. Upon initiating raking action by placement of tines 170 in contact with an expansive surface, tines 170 deflect as shown in FIG. 15A, with the deflection superimposed on arc of displacement DD previously shown in FIG. 14A. In this configuration, each of tines 170 forms a concave arcuate curve C1. As shown in FIG. 15B, during raking action, upon release of tines 170 from contact with the ground, tines 170 deflect forward, the deflection superimposed on arc of displacement DD' previously illustrated in FIG. 14B. The forward deflection results from the resilient elasticity of tines 170 which causes a release of elastic strain energy that is stored in tines 170 when tines 170 are in the configuration of FIG. 15A. The release of the elastic strain energy causes the forward propelled movement of each tine 170 within apertures 164 in addition to a counterbending of each tine 170 to form a convex arcuate curve C2.
Apertures 164 have consequently magnified the effect of the deflection of tine 170 by allowing a greater physical movement of tines 170 before the forward deflection of tine 170 is stopped by the contact of stem 172 with bottom aperture 164b. The greater physical movement of tines 170 produces the effect of greater physical movement of leaves and lawn debris, thus propelling the leaves and lawn debris father than would occur with apertures that allowed no freedom of movement to tines 170. In addition, tines 170 have a relatively long period of oscillation due to their long unsupported length and consequently tines 170 are able to remain in contact with, and transfer energy to, leaves and lawn debris for a longer period of time.
Apertures 164 that are oversized with respect to stem 172 offer an additional benefit in the present invention. The formation of concave curve C1 and convex curve C2, in FIGS. 15A and 15B, respectively, include curvature of stem 172 where it passes into, through, and out of cross arm 145, by means of apertures 164. The curvature of stem 172 continues to the point where stem 172 forms a juncture with bend 178. As tine 170 deflects, bend 178 shifts in position on cross arm 145 according to the internal forces that develop within stem 172 due to the applied bending moments. Without the oversized opening of aperture 164b, stem 172 would be fixedly held where stem 172 first passes into cross arm 145, as a cantilever with a rigid support. Maximum bending stresses would occur at this point. Instead, the curvature of tine 170 continues inside of cross arm 145 such that flexity can develop where stem 172 joins bend 178, to form an elastic support. A coupled pair of forces develops at the points where stem 172 contacts top aperture 164a and bottom aperture 164b, to help resist the applied bending forces, in conjunction with the mechanical anchoring of bend 178 in contact with cross arm 145. Bend 178 serves as a moving anchorage, having an inherent looseness for movement circumferentially around cross arm 145, or rotatably around stem 172, that serve to reduce the stresses in tine 170.
As a method of operation for raking action, lawn rake 100 possesses all of the lawn raking characteristics of most other broom style lawn rakes in the prior art. Tines 170 have considerable lateral flexibility so that tines 170 may deflect around a protruding object after lawn rake 100 begins to be drawn across a lawn. Generally, however, tines 170 remain in substantially straight and parallel alignment during straight-ahead raking action. This alignment is achieved by the engagement of bend 178 with cross arm 145, serving to act as a rudder for tines 170 to keep them in alignment, thus maintaining tips 176 in an orientation that is generally perpendicular to the expansive surface upon which lawn rake 100 operates. The circular surface of tips 176 presents a relatively large area of contact with the expansive surface and thus there is less of a tendency for tines 170 to dig into the expansive surface, compared to a rake that does not have tines with circular tips. Therefore, raking resistance developed as a result of tips 176 contacting the expansive surface, and thus raking effort, is also less. In addition, the cylindrical nature of stems 172 offers less resistance to grass through which tines 170 are moving, minimizing the tearing and ripping of grass as tines 170 pass.
Lawn rake 100 also possesses unique characteristics of manipulation that increase its effectiveness in gathering leaves and lawn debris. As demonstrated in FIG. 14C, pivotal freedom of movement of tines 170 allows looped bend 178 to rotate back and forth. This rotation can take place when there is a change in direction of lawn rake 100 away from a straight-ahead direction. Manipulation of lawn rake 100 can therefore have a sideways component or an arcuate component of motion not achievable with other lawn rakes. Tines 170 with a circular cross section have uniform strength and uniform flexity in all directions. Thus, tines 170 easily flex, and looped bends 178 quickly align, to accommodate any raking direction, or change in raking direction. Torsional stresses on tines 170 are consequently reduced. The fixed rectangular tines of other lawn rakes do not possess this ease of manipulation in different and changing directions.
The attributes of manipulation that are unique to the present invention are illustrated in FIGS. 16A-C. A top view of lawn rake 100 in raking position is shown in FIG. 16A. As described earlier, direction of movement M denotes conventional, straight-ahead raking action. Straight-ahead raking action is usually the only direction of manipulation possible with lawn rakes of the prior art having flat, rectangular tines. For lawn rake 100, directions of movement M1, M2, M3, M4, M5, and M6 are shown as representative directions of raking action that can be accomplished in addition to movement M. Movements M1, M2, M3, M4, M5, and M6 can be accomplished due to the uniform stiffness provided by tines 170 having a circular cross section, and due to the pivotal freedom of movement of tines 170 mounted on cross arm 145.
Movements M1-6 are especially unique in the present invention because they can take place while cross arm 145 remains parallel to its original orientation shown in FIG. 16A. Thus, users of lawn rake 100 do not have to move their feet as frequently in order to rake a larger area. In FIG. 16B, lawn rake 100 is shown having progressed from its position in FIG. 16A with components of movement both ahead and to the right. For tines 170 having a uniform stiffness in all raking directions, a user of lawn rake 100 does not notice a change in raking resistance due to a different raking direction or to a change in raking direction, all while the tines remain in contact with the ground. The characteristics of lawn rake 100 also allow direction of movement M6 that only has a sideways component, such as might be encountered in trying to sweep wet eaves from a curb gutter or from flower bed edging. Thus, lawn rake 100 may be manipulated laterally to progress from its position in FIG. 16A to its position in FIG. 16C. Movements M1-6 are only representative and any direction of movement or combinations of directions of movement can be achieved in the quadrant defined by movements M1 and M6. Movements M1-6 are shown having components of lateral movement rightward. Similar movements leftward are equally possible.
Lawn rake 100 has an additional method of operation that involves the pushing of leaves and lawn debris in a series of pushing motions, much as one would use a push broom. The pushing motion may also be one continuous forward movement of moving an accumulated pile of leaves and lawn debris as the user walks behind lawn rake 100 while pushing lawn rake 100 in a forward direction. Lawn rake 100 is shown in FIG. 17 configured to accomplish a pushing action. Tines 170 deflect to form a convex arcuate curve C3. Storage of elastic strain energy in stems 172 of tines 170 provides a springy resilience that maintains tips 176 in contact with the ground. An angle G is an acute angle subtended by tips 176 and the expansive surface. Any time that the pressure on tines 170 is reduced so that stems 172 can straighten out, tips 176 spring forward to sweep the lawn in front of tips 176 clear of leaves. Aspects of tines 170 explained in relation to FIGS. 15A and B, contribute to the capability of lawn rake 100 to operate in a leaf and lawn debris pushing mode.
Alternatively, the forward springing motion of tips 176 urges any pile of accumulated leaves and lawn debris that is being moved, clear of tips 176. Consequently, the method of operation of pushing leaves is an effective means for rapidly moving an accumulated pile of leaves and lawn debris without having to repetitively apply a series of raking actions to rake leaves toward the user as the user backs up step-by-step. Angle A (shown in FIG. 2), together with angle B, is the determining factor that enables pushing mode operation to be accomplished. Angle A allows the user of lawn rake 100 to hold handle 120 in one's hands, with tines 170 in contact at angle B (FIG. 2) with respect to the ground, and apply a forward movement MM to lawn rake 100 that allows tines 170 to deflect without exceeding the elastic limit of the material of which tines 170 are composed. Tines 170 then deflect back towards the user, with the edges of tips 176 maintaining contact with the ground to provide a moving barrier trapping and forwardly urging leaves and lawn debris.
Alternative configurations of tines are shown in FIGS. 18A-E. A tine 190 in FIG. 18A has a looped bend 198 turned downwards so that tine 190 engages cross arm 145 from below. Tine 190 otherwise possesses the same attributes as tine 170. In FIG. 18B, a tine 210 includes a looped bend 218 that becomes cotangent with a segment 215, terminating in a tine end 220. A tine 230 in FIG. 18C includes a looped bend 238 that turns downward so that tine 230 engages cross arm 145 from below. Bend 238 is cotangent with a segment 235, terminating in a tine end 240. Tines 210 and 230 differ from tines 170 and 190, by substitution of straight segments 215 and 235, for part of bends 218 and 238, respectively. In FIG. 18D, a tine 250 includes a bend 258 that provides additional clearance and looseness of bend 258 when tine 250 is mounted on cross arm 145. A tine 270 in FIG. 18E includes a bend 278 similar to bend 258 except that it turns downward, engaging cross arm 145 from below.
Tines 190, 210, 230, 250, and 270, all have bend 174 proximate ground engaging tip 176. Tines 190, 210, 230, 250, and 270, all have the same attributes of removability, insertability, releasability, and energy absorption already described with regard to tine 170. Tines 190, 210, 230, 250, and 270, may each have the same material of composition as tine 170.
Usable with all of tines 190, 210, 230, 250, and 270, or any other tine having a circular cross section, is a ground engaging tip 177 as shown in FIG. 19. Tip 177 has a rounded or hemispherical shape that provides less resistance to raking action when drawn across the ground. Tip 177 further tends to ride up and over any irregularities in a lawn surface. The rounded nature of tip 177 also tends to deflect stem 172 laterally upon application of an upwardly force on tip 177 during raking action rather than transmitting the force upwards along stem 172 to cause release of tine 170 or any other tine, from cross arm 145. This occurs because an upwardly directed force on tip 177, unless applied dead center to tip 177, would impact the roundness of tip 177 at an angle not normal to tip 177. Consequently, the resultant force on tip 177 would have both a vertical component and a horizontal component, the horizontal component tending to cause tip 177 to move sideways. Thus, the upward effect of the force is deflected laterally and diminished.
As explained earlier, apertures 164 having a diameter that is larger than the diameter of tines 170 provide an additional benefit during raking action other than for releasability of tines 170. During raking action, tines 170 deflect backwards as tines 170 are drawn across an expansive surface such as a lawn. Upon release of tines 170 from contact with the ground, the release of the elastic strain energy stored within tines 170 as a result of the deflection, cause tines 170 to unbend and recoil. The larger diameter of apertures 164 allows tines 170 to counterbend past the undeflected equilibrium position and provide greater forward urgement to leaves and lawn debris than a lawn rake having tines with no freedom of movement at their anchoring point. This counterbending action can be enhanced by using a slotted bottom aperture instead of a circular aperture.
FIG. 20 is a partial bottom view of a cross arm 345 having a plurality of circular top apertures 364 and a plurality of slotted bottom apertures 365. The centers of top apertures 364 and bottom apertures 365 are diametrically aligned with respect to cross arm 345. Top apertures 364 of cross arm 345, can be seen through bottom apertures 365 in FIG. 20. A width w of bottom apertures 365 is identical to the diameter of top apertures 364. A length L is the length of the slot of bottom apertures 365. The long direction of bottom apertures 365 is oriented perpendicular to the axis of cross arm 345. Length L is a predetermined value that provides optimal forward urgement to leaves and lawn debris during raking action, when tines 170 are lifted off the ground. Length L allows tines 170 greater front-to-back movement associated with the storage and release of elastic strain energy during raking action as explained with reference to FIGS. 15A and B.
An alternative cross head assembly 430 is shown in FIG. 21. Cross head assembly 430 includes a truncated tee 450, a cross arm 445, and plurality of tines 170. For cross head assembly 430, the width of truncated tee 450 is a value such that uniform parallel side-by-side spacing of all tines 170 can not be accomplished. A tine 170l and a tine 170m are located adjacent the sides of truncated tee 450, respectively. A tine 170k is adjacent tine 170l, and a tine 170n is adjacent tine 170m. In order to maintain uniform tip spacing t, tines 170l and 170m are convergent Truncated tee 450 may have tapered ends to accommodate the convergence of tines 170l and 170m. An aperture spacing s denotes the center-to-center distance of top apertures 164a and bottom apertures 164b of adjacent tines 170 that are parallel. Tines 170 and 170m are each installed through a pair 162 of a top aperture 165a and a bottom aperture 165b. Aperture spacing s is equal to tip spacing t. As further shown in FIG. 21A, an aperture spacing s' denotes the center-to-center distance of top aperture 165a of tine 170l from top aperture 164a of tine 170k, as well as the center-to-center distance of top aperture 165a of tine 170m from top aperture 164a of tine 170n.
In FIG. 21B an aperture spacing s" denotes the center-to-center distance of bottom aperture 165b of tine 170l from bottom aperture 164b of tine 170k, as well as the center-to-center distance of bottom aperture 165b of tine 170m from bottom aperture 164b of tine 170n. For tip spacing t of 7/8 of an inch, aperture spacings s' and s" for convergent tines 170l and 170m are approximately 1/2 inch and 9/16 inch, respectively. In this arrangement, apertures 165a and 165b are not diametrically opposed. For cross head assembly 430, apertures 165a are colinear with apertures 164a and apertures 165b are colinear with apertures 164b. All other structural and operational characteristics of cross head assembly 430 are the same as cross head assembly 130.
In FIG. 22 an alternative cross head 540 is shown. Cross head 540 includes a cross arm 545 and plurality of pairs 162 of diametrically opposed apertures 164. In contrast to cross arm 145, apertures 164 of cross arm 545 are not arranged in a colinear manner. Instead, apertures 164 for cross arm 545 may be arranged in an arcuately curved manner, as shown in FIG. 22. The benefit of this arrangement is shown in FIG. 23 where tines 170 are shown mounted on cross arm 545. The arcuate arrangement of apertures 164 along cross arm 545 causes tines 170 to be displaced one from another. An array 161 of tines 170 is consequently not coplanar and instead forms a gently curving convex arrangement of tines 170. The attributes of cross arm 445 of cross head assembly 430 shown in FIG. 20, having aperture spacing s' for apertures 165a and aperture spacing s" for apertures 165b, may be combined with the attributes of cross arm 545.
Other arrangements of apertures on cross arms are feasible, offering varied benefits in the present invention. A cross head 550 in FIG. 24 shows a cross arm 555 with apertures 164 in a pattern of staggered pairs such that tines 170 align in two alternating rows. A cross head 560 in FIG. 25 shows a cross arm 565 with apertures 164 in a pattern of staggered triplets such that tines 170 align in three sequential rows. Many other patterns are possible due to the unique characteristic of the tubular cross arm in the present invention to situate tine engaging apertures anywhere around or along the cross arm, independently of the apertures of adjacent tines. Thus, it has been demonstrated for any cross head assembly of the present invention, that the three dimensional spatial relationship of tines 170 to form an array can be infinitely varied without consideration of structural relationships of one tine to another. Furthermore, the variation of tine orientation and array configuration can take place independently of other components of the cross head assembly. This capability is a direct consequence of the tubular nature of the cross arms of the present invention and the mounting method for the tines.
Cross arm 555 is shown in side view in FIG. 26 with tines 170 mounted thereon. A row R1 and a row R2 distinguish between the two rows of tines within which tines 170 are alternately disposed. Cross arm 565 is shown in side elevation view in FIG. 27 with tines 170 mounted thereon. A row R3, a row R4, and a row R5 distinguish between the three rows of tines within which tines 170 are sequentially disposed.
A cross arm 645 that has apertures that are not diametrically opposed is shown in FIG. 28. A top aperture 664a and a bottom aperture 664b comprise a pair 662 of apertures 664. Cross arm 645 differs from cross arm 145 of FIG. 5 in that apertures 664 are oppositely aligned along a chord of cross arm 645. It can thus be said that apertures 664 are chordally opposed, with diametrically opposed apertures 164 previously described being a specific case of a chord that is located on a diameter of cross arm 145.
A tine 670 shown in FIG. 29 for use with cross arm 645 includes a stem 672 with a looped bend 678 that semicircularly engages cross arm 645. A line tangent to bend 678 where bend 678 intersects stem 672, subtends an obtuse angle V with stem 672. Obtuse angle V so approximated subjects tine 670 to less stress than tine 170 would be subjected to as a result of the generally perpendicularly intersection of bend 178 with stem 172. Tine 670 otherwise retains similar characteristics of insertability, removability, releasability, and energy absorption, as tine 170. FIG. 29A is an enlargement of bend 678 in engagement with cross arm 645 showing the chordally passage of tine 670 through apertures 664. A partial top view of cross arm 645 is shown in FIG. 30, taken in the direction D of FIG. 28. Cross arm 645 is thus shown with apertures 664 in colinear alignment.
Lawn rake 100 further possesses the capability of being sold commercially disassembled. The ease of removal and installation of tines 170 disposes lawn rake 100 to be readily assembled from a kit of parts. In particular, the elongated nature of handle 120, cross head 140, and tines 170, lends to lawn rake 100 being packaged disassembled in a cylindrical mailing tube for direct shipment to individual customers. Of course, lawn rake 100 also retains the ability to be sold as a kit of parts in a retail store, as well as being sold completely assembled in a retail store. In FIG. 31 a cylindrical mailing tube 700 illustrates the packaging of lawn rake 100 as it might be accomplished within tube 700. Tube 700 may have a diameter of approximately three inches or more for the ease of packaging lawn rake 100 as separate components.
For those persons who do not want to install each individual tine, lawn rake 100 can also be packaged as two separate components comprising handle 120 and cross head assembly 130. Packaging of lawn rake 100 in this manner generally results in a relatively long, narrow, and flat package, that also lends itself to being shipped mail order. A mailing container that is flat and rectangular may have dimensions of approximately 52 inches high by 12 inches wide by 1 and 1/2 inches thick for shipping lawn rake 100 as separate components of handle 120 and cross head assembly 130. With a handle that is disassemblable into two separate pieces, an even more compact shipping container can be utilized that might have dimensions of only 26 inches high by 12 inches wide by 1 and 1/2 inches thick. Other packages with different dimensions may serve equally well. What has been accomplished is the reduction of empty space within a mailing container that would otherwise increase the size of a mailing container as well as the cost of shipping.
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