Abstract:
A retractable pet leash system allows a pet to vary its distance from the leash system, with the system paying out additional leash as needed, and when not needed, automatically retracting the leash back into the system. If at any time a user desires to halt further payout of leash, the user presses a button that causes the leash to be pressed against a frictional element that causes braking of leash payout at a gradually increasing rate while simultaneously, a lever lockably engages the spool preventing further rotation of the spool in the payout direction.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a retractable pet leash that has a user controlled brake wherein the braking action generated by the brake decelerates, at a gradually increasing rate, the payout of the leash from a leash housing in order to help prevent undue discomfort and injury to a pet using the leash. 
     2. Background of the Prior Art 
     Pets, especially dogs, need to be taken outside regularly and allowed to walk or run in order for the dog to do its business as well as to give the dog some exercise and fresh air. While some pet owners have the luxury of allowing their dog to run free, such as dogs on a farm, most dog owners must walk the dog with the dog in close proximity to the owner. Some dogs can be walked independently, that is without being tethered to the dog walker via a leash, however, many other dogs must be walked on a leash. The requirement for a leash is multifold. Many jurisdictions, or even housing neighborhoods have mandatory leash laws requiring dogs, even the smallest of dogs, to be on a leash at all times while outdoors. Such dog walkers place their dog on a leash lest they run afoul of their neighbors or law enforcement. Other dogs are leash walked for the protection of the dog. A dog, even a well-disciplined dog, walking down a busy street may become distracted or otherwise desire to bolt from its owner for a variety of reasons. But for the leash, the dog may run into traffic and be hurt or killed, not to mention the potential for a traffic accident as a driver serves to try and avoid hitting the animal. Some dogs, especially larger dogs are leashed for the protection of others. Even the friendliest of dogs can bite others, such as small children who believe that poking a dog in the eye is great fun. Leashing the dog allows the owner to maintain the dog a safe distance from potential bite victims of the dog. 
     There are two broad categories of leashes currently being used for dog walking (and cat walking for the brave). The fixed length leash is a single length tether that typically has a handle on the dog walker&#39;s end, and a clip on the opposing end that clips onto an appropriate receiver of a collar that encircles a dog&#39;s neck. The leash is clipped onto the dog&#39;s collar, the walker grasps the handle and the walk or run commences. Tried and true, such leashes find favor with many dog owners. While effective, such leashes are not without their drawbacks. The fixed length nature of the leash does not permit the animal to venture far from its handler. Although this limitation may prove satisfactory in many situations, often the dog desires to venture a bit further from its owner than can be accommodated by such a leash. For example, on a quiet neighborhood street when the handler decides to stop and chat with a neighbor, the dog may want to sniff some trees beyond the reach of the leash. Often, in such situations, the dog may repeatedly try to tug on the leash in order to venture beyond the travel limits of the leash, which repeated tugging is uncomfortable on dog and handler alike. Additionally the leash can become entangled within either the dog&#39;s or the handler&#39;s legs, especially in longer length fixed length leashes, creating a potential hazard. 
     To address the limitations of fixed length leashes, variable length leashes have been proposed. These leashes have a housing that has a spool therein, about which the leash is wound. The housing has a handle for ease of holding while the distal end of the leash has the typical clip thereon for clipping the leash onto the dog&#39;s collar. When the dog is clipped to the leash and begins to walk and thus move away from the housing, the leash is paid out from the housing, being unwound from the spool. The length of such leashes is usually much longer than a typical fixed length leash allowing the dog to venture farther compared to the fixed length leash. When the dog ventures back toward the leash housing, the leash is retracted back into the housing and wound back about the spool, usually automatically in some appropriate spring-loaded architectures, although some manual rewind systems exist wherein the handler rewinds the leash onto the spool by turning an appropriate crank. Such systems have locks that lock the leash in a fixed length so that if the handler wants the dog at a fixed distance from the handler, for example on a busy street wherein the dog must remain close to the side of the handler, once the desired length of leash is paid out from the housing, a lock is set fixing the length of the leash, the leash cannot neither get longer nor shorter while so locked. Many systems allow the handler to either temporarily hold the leash in this fixed length by maintaining pressure on the brake, or to hold the leash in this fixed length indefinitely by placing the brake into a locked position. This type of leash, while more expensive than a typical fixed length leash, allows a dog to have more independence during a typical walk, while allowing the handler to maintain tight control of the dog when the situation warrants. 
     While favored by many dog owners, variable length leashes are not without their drawbacks. One of the chief problems with these types of leashes centers on the situation when the owner must suddenly terminate further payout of the leash from the spool. For example, when the dog suddenly darts toward another person walking down the street, the handler needs to terminate further advancement of the dog in order to prevent the other person from becoming scared or injured. To halt further payout of the leash, and thus advancement of the animal, the handler throws the device&#39;s brake, locking the spool. 
     The problem with this braking is that the payout suddenly stops, halting the animal in its tracks. If the dog is running at full stride, suddenly braking the leash to a halt can not only be quite painful, it can also result in injury to the animal. To address these problems, many retractable leash systems have brakes that gradually decelerate under a sudden stop so that the animal is stopped gradually as opposed to suddenly. These systems, which come in a wide variety of architectures and work with varying degrees of efficiency, help prevent discomfort and injury to the animal. However, such systems are not without their drawbacks. 
     Some systems are relatively simple and place a resilient section of leash at the distal end of the leash in order to act as a deceleration spring. When the leash is suddenly halted due either to braking by the handler, the resiliency of this section of the leash slows the animal down gradually. The problem with these types of deceleration systems is that the resilient portion of the leash must be relatively thin in order to approximate the thickness of the remainder of the leash to assure the leash&#39;s proper operation. As such, if the animal pulls hard on the leash, the resilient portion, by being relatively thin, will have a relatively low spring constant, allowing the leash to be stretched relatively far. Once the resilient portion is stretched to its outer limit, this portion snaps back under its spring action. This snap back is uncomfortable to animal and handler alike, and can result in the animal stumbling from this unexpected reversal of course. Still other systems use a step brake deceleration system that has a brake latch contact and ride over several one way ramps before finally becoming ensnared by such a ramp and halting spool unwind. This type of system causes a bumpy and jagged deceleration which is very uncomfortable to animal and handler alike. Still other systems are unusually complex in design and construction so as to make such systems relatively expensive to produce. Additionally, the complexity of such systems increases the potential for failure of the device resulting in the need to repair the device or replace the device. 
     What is needed is retractable leash that has gradual deceleration of the leash when payout is halted due to the handler engaging the brake of the device, which retractable leash overcomes the above stated shortcoming found in the art. Specifically, such a retractable leash must be able to gradually decelerate the leash payout so as to help prevent discomfort and injury to the dog, and possibly the handler, in a smooth efficient manner. The retractable leash must not have a sudden rapid snap back of the leash whenever the animal&#39;s progress is halted due to leash braking. The gradual deceleration of the retractable leash must be smooth, not bumpy or jagged. The retractable leash must be of relatively simple design so as to be relatively easy to produce and maintain. 
     SUMMARY OF THE INVENTION 
     The retractable leash with gradual braking of the present invention addresses the aforementioned needs in the art by providing a typical retractable type of leash that has a spool held within a housing about which a leash is wound such that the leash is paid out of the housing when needed and is automatically retracted back into the housing and wound back about the spool when not needed. The retractable leash with gradual braking has a user controlled brake that allows further leash payout from the housing to be stopped which brake decelerates the leash payout at a gradually increasing rate. During leash payout deceleration, the braking is smooth and the leash does not experience a sudden snap back once halted. The retractable leash with gradual braking is of relatively simple design and construction, being produced using standard manufacturing techniques, thereby making the device relatively inexpensive to produce and maintain so as to make the device economically attractive to potential consumers for this type of device. 
     The retractable leash with gradual braking is comprised of a leash housing that has a spool rotatably disposed therein. A lock lever is pivotally disposed within the housing. The lock lever articulates between a normally relaxed first position wherein the lock lever is disengaged from the spool and a second position wherein the lock lever is engaged with the spool and prevents the spool from rotation but does not prevent spool counter-rotation. A friction element is disposed within the housing. An engagement cam has a base and a top and a central opening therebetween such that the engagement cam straddles the friction element such that the friction element is located within the central opening. The engagement element articulates between a normally relaxed third position wherein a top end of the friction element abuts the top of the engagement cam and a fourth position wherein the base of the engagement cam abuts a rounded bottom of the friction element. When the lock lever is in the first position, the engagement cam is in the third position and as the lock lever articulates toward the second position, the lock lever urges the engagement cam toward the fourth position and as the lock lever returns back toward the first position, the engagement cam returns, in lockstep, back toward the third position. A tether is wound about the spool and is retractably paid out through an opening on the housing. The tether passes through the engagement cam such that when the lock lever is in the first position and thus the engagement cam is in the third position, the tether passes along the base of the engagement cam and does not engage the friction element. As the lock lever is moved toward the second position, thereby urging the engagement cam toward the fourth position, the base of the engagement cam moves a portion of the tether into frictional engagement with the bottom of the friction element, the frictional engagement increasing as the engagement cam moves toward the fourth position and with decreasing frictional engagement as the engagement cam moves toward the third position, the tether being disengaged from the friction element whenever the engagement cam is in the third position. A spring having a spring constant is attached to the spool and to the housing in order to spring-load the spool so that pay out of the tether from the housing operates against the bias of the spring, thereby allowing automatic refraction of the tether back onto the spool via the spring-loading. The spring constant of the spring is adjustable. A spring-loaded button is disposed within housing and abuts the lock lever such that button articulates between a normally relaxed fifth position wherein the lock lever is in the first position and a sixth position wherein the button urges the lock lever into the second position such that the spring-loading of the button attempts to urge the button toward the fifth position. A stop is disposed within the housing such that the button is removably placed against the stop in order to hold the button in the sixth position against the spring-loading of the button. A plurality of equidistantly spaced teeth is located on an outer surface of the spool and arranged in a circle, such that each tooth has a first side with a one-way ramped surface and a second side with a stop surface (flat to slightly curved) such that whenever the spool is rotating in the direction of tether pay out, the second side of each tooth is the leading edge and such that whenever the lock lever is in the second position, the lock lever engages the second side of one of the teeth and thereby prevents the rotation of the spool in a tether pay out direction, yet when the spool rotates in a counter direction, the lock lever (in the second position) rides overtop the first side of each tooth. The base of the engagement cam has a pair of ends and a curved medial portion. The shape of the curved medial portion corresponds to the shape of the lower end of the friction element such that this lower end is received within the curved medial portion with the tether sandwiched therebetween, whenever the engagement cam is in the sixth position. The housing has a handle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental view of the retractable leashing with gradual braking of the present invention with the cover removed to illustrate the interior mechanics. 
         FIG. 2  is a perspective view of the retractable leashing with gradual braking with the cover removed to illustrate the interior mechanics, the device in an initial, ready to use position. 
         FIG. 3  is a perspective view of the retractable leashing with gradual braking with the cover removed to illustrate the interior mechanics, the device in a latched position. 
         FIG. 4  is a perspective view of the retractable leashing with gradual braking with the cover removed to illustrate the interior mechanics, the device in a locked position. 
         FIG. 5  is an exploded perspective view of the adjustment knob mechanism used to adjust the spring tension of the spool. 
     
    
    
     Similar reference numerals refer to similar parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, it is seen that the retractable leashing with gradual braking of the present invention, generally denoted by reference numeral  10 , is comprised of a main housing  12  and a corresponding cover  14  that correspondingly attaches, either fixed (adhesive, ultrasonically welded, etc., or removably, screws, etc.,) to the housing  12 . The main mechanical components of the retractable leashing with gradual braking  10  are held within the housing  12  and attached cover  14 . The housing  12  and its cover  14  are made from an appropriate material, such as plastic. 
     As seen, the housing  12  has a generally circular area  16  that has a centrally located post  18  thereat, the post  18  having a hollow central cavity  20 . A spool system is rotatably disposed within the circular area  16  and is capable of rotating and counter-rotating therein. The spool system comprises a spool  22  that has a central channel  24  upon which a tether  26  is wound. A series of ramped teeth  28  are circumferentially located on each side of the spool  22 , each tooth  28  on one side of the spool  22  aligned with a corresponding tooth  28  on the opposing side of the spool  22 , each tooth  28  spaced equidistantly from its adjoining teeth  28 . A central inner opening  30  is located on the spool  22 , such that a coil mount  32  has a first end  34  fixedly secured to a surface of the central inner opening  30  and a second end  36  that is free and may have a small lip  38  thereon. A coiled leaf spring  40  has a small loop  42  on its outer end that is mounted onto the coil mount  32 , the lip  38  of the coil mount  32  helping hold the leaf spring  40  thereon. As such, the leaf spring  40  occupies the central inner opening  30 . A coil spring  44  is disposed within the cavity  20  of the post  18 . An adjustment knob  46  has a hollow central core  48  with a longitudinal slit  50 . A plate  52  is located at the top of the core  48  with a stub  54  extending outwardly from the plate  52  and a finger grip  56  extending from the stub  54 . Circumferentially located about the plate  52  and encircling the stub  54  are a series of one way ramps  58 , each ramp  58  spaced equidistantly from its adjoining ramps  58 . As seen, the cover  14  has a central opening  60 . Circumferentially located about the central opening  60 , on the inner facing surface of the cover  14 , are a series of ramp receivers  62  that are dimensioned to receive the ramps  58  of the adjustment knob  46 . 
     In order to assemble the spool system, the leaf spring  40  has its loop  42  fitted onto the coil mount  32  and the spool  22  is placed into the circular area  16  of the housing  12 . The coil spring  44  is placed into the cavity  20  of the post  18 . The adjustment knob  46  is inserted into the central inner area of the leaf spring  40  such that a portion of the leaf spring  40 , proximate its inner end, passes through the slit  50  of the central core  48 . Thereafter the cover  14  is affixed to the housing  12  in appropriate fashion. In this position, the stub  54  of the adjustment knob  46  protrudes through the central opening  60  of the cover  14 . The ramps  58  on the adjustment knob  46  are each received within a respective one of the ramp receivers  62  on the cover  14 , with the coil spring  44  biasing against the housing  12  and against the plate  52  in order to maintain the adjustment knob  46  in this position. The adjustment knob  46  is used to adjust the tension of the leaf spring  40  as more fully explained below. 
     Looking now to  FIGS. 1-4 , the brake mechanism comprises a push button  64  that has a body with a central opening  66 , an outer wall  68 , and a pair of extension arms  70  extending outwardly from the body  64  on an end opposite the end bearing the outer wall  68 , each extension arm  70  being generally flat on its lower side and upwardly curved on its upper side. A spring post  72  is fixedly secured to the housing  12  such that the spring post  72  passes through the central opening  66 . A push button spring  74  has one end biased against the spring post  72  and an opposing end biased against the outer wall  68  of the push button  64 , thereby spring-loading the push button  64 . A cam  76  and a lock lever  78  are each pivotally attached to the housing  12  via a pivot pin  80  with the lock lever  78  straddling the cam  76 , with the cam  76  connected to the lock lever  78  so that the two elements  76  and  78  rotate in lockstep. The upper end of the cam  76  is rotatably connected to the extension arms  70  via a pin  82 . As seen, the lock lever  78  is comprised of a pair of identical lever arms  84  that each extend from the pivot pin  80  and terminate in a head  86 . Each head  86  has an outwardly rounded top  88  and backside  90  and a flat or slightly inwardly curved front side  92  and bottom  94 . A teardrop shaped friction element  96  is attached to the housing  12  while an engagement cam  98  has a body  100  that has an outwardly rounded bottom  102  with a inwardly rounded upper surface  104  and a pair of spaced apart arched elements  106  coextend upwardly from the body  100  such that a connector  108  connects the two arched elements  106  at their tops. The engagement cam  98  is connected to the housing  12  via an arm  110  that has one end pivotally attached to the body  100  and the opposing end pivotally attached to the housing  12 . 
     In order to use the retractable leashing with gradual braking  10  of the present invention, the tether  26  is wound about the spool  22  and connected thereto in the usual way with the tether  26  extending out from the housing  12  through an appropriate opening  112  on the housing  12 . The distal end of the tether  26 , which may have an appropriate clip  114  or other attachment device thereon, is attached to the animal I in the usual way and the animal I can be walked in normal fashion, the user grasping the retractable leashing with gradual braking  10  via a handle  120 . When the retractable leash with gradual braking  10  is in the initial position, as seen in  FIG. 2 , the push button  64  extends outwardly from the an opening  116  in the housing  12  biased in such position by the push button spring  76  and limited in its extension by the cam  76 . The tether  26  passes over the upper surface  104  of the body  100  of the engagement cam  98  and pulls the body  100  downwardly so that upper larger rounded end of the friction element  96  biases against the connector  108  of the arched elements  106 . In such position, the tether  26  experiences no contact and thus no friction from the frictional element  96  and little to no contact with the body  100  and thus little to no friction therefrom. As the animal I moves away from the retractable leashing with gradual braking  10 , spool  22  rotates in order to allow more tether  26  to be paid out from the housing  12 . As the spool  22  rotates, the leaf spring  40  is further coiled thereby spring-loading the spool  22 . When the animal I moves toward the housing  12 , the spool  22 , via the spring bias of the leaf spring  40 , counter-rotates thereby retracting the tether  26  back into the housing  12  and winding the retracting tether  26  about the spool  22 . If the animal moves sufficiently far away from the housing  12  so as to fully unwind the tether  26  from the spool  22 , further movement away from the retractable leashing with gradual braking  10  causes increased coiling of the leaf spring  40 , until the animal I can no longer further coil the leaf spring  40  resulting in a stop. As the braking action is due to a leaf spring  40  as opposed to a coil spring or its equivalent, the braking is gradual, not sudden, and any retraction that may occur, is both slight and gradual. 
     If the user desires to stop the animal I when the animal I is moving away from the housing  12 —for example, the animal I is about to run into a busy street—the user pushes the push button  64  inwardly into the housing  12 . As the push button  64  is being pressed inwardly, the top of the cam  76 , being connected to the extension arms  70 , rotates such that the bottom of the cam  76  pushes against the rounded bottom  102  of the body  100  of the engagement cam  98  pushing the engagement cam  98  generally away from the spool  22 . This causes the outer edges of the upper surface  104  of the body  100  to engage the tether  26  and push the tether  26  the friction element  96 , eventually pushing the rounded upper surface  104  of the body  100  into the relatively narrow bottom of the friction element  96  with the tether  26  sandwiched therebetween in a generally “W” shaped configuration. This action causes the upper surface  104  to exert increasing friction on the tether  26  and eventually for the friction element  96  to also exert friction on the tether  26 . This increased friction on the tether  26 , makes movement of the tether  26  in either direction increasing difficult, resulting in deceleration of tether  26  pay out (or refraction) for a given force, such as for the animal I running at a constant speed. As the frictional engagement by the upper surface  104  of the body  100  as well as the frictional element  96  upon the tether  26  is gradual, increasing with increased inward push button  64  movement, the braking action performed by such frictional engagement is also gradual, resulting in a more gradual and controlled stop of the animal&#39;s movement. Simultaneously, as the push button  64  is being pushed inwardly, the lock lever  78  rotates toward the spool  22  until the forward end of the head  86  is in the path of the teeth  28  of the spool  22 . The flat surface of the teeth  28  engage the bottom  94  of the head  86  thereby preventing further rotation of the spool  22  in the payout direction. The push button  64  can be held in one of two positions. In a latched position, illustrated in  FIG. 3 , the bottom surface  94  of the head  86  engages the flat side of one of the teeth  28 , however, the head  86  is not fully seated within the gap between the teeth  28 . The push button  64  is angled somewhat upwardly with the outer wall  68  of the push button  64  facing a lip  118  on the housing  12 , but not necessarily engaging it. For the push button  64  to be in the latched position, the user holds the push button  64  in this configuration via his or her thumb. In the latched position, the spool  22  is not free to rotate in a tether payout direction. The user can then place the push button  64  into the locked position, illustrated in  FIG. 4 , by simply releasing the push button  64  so that the outer wall  68  of the push button  64  engages the lip  118  on the housing  12  biased thereagainst by push button spring  74 . This causes the push button  64  to lose its slight upwardly angling so that the head  86  of the lock lever  78  is now fully seated within the gap between two teeth  28 . The user can release the push button  64  from its locked position by pushing the push button  64  via its outer wall  68  slightly inwardly and thereafter pushing on the outer wall  68  slightly upwardly so that the push button  64  clears the lip  118  on the housing  12  and partially exits the housing  12  under the bias of the push button spring  74 , returning back to the initial position wherein the spool  22  is free to rotate and counter-rotate. 
     When the lock lever  78  passes the corner  122  of the tooth  28  at the non-curved side of the tooth  28  on its way to the base  124  of the tooth  28 , the arched element  106  of the friction element  98  has reached its furthest position, so the contact surface on the arched element  106 , between free points  126  and  128  (slight curvature of the arched element between these two points) is such that the lock lever  78  can move freely between the corner and the base of the tooth  28  without changing the position of the friction element. Without this curvature and free movement of the friction element  98 , the lock lever  78  would latch before the friction element  98  had fully engaged, or the friction element  98  cam would already be fully engaged and prevent the lock lever  78  from moving past the corner of the tooth  28  and possibly cause mechanical failure. 
     It is also noted that the curvature of the surface arched element  106  from contact point  128  back to its initial contact position is shaped such that for each degree of rotation of the lock lever  78  (starting from its initial position), the distance the friction element  98  moves increases at an increasing rate. In other words, this curved surface of the arched element is curved (like a parabola) to maximize a cushioning effect. In conjunction with this, the lock lever  78  contact surface is shaped such that (starting from the lock lever&#39;s initial position) the distance from the point of contact to the center of rotation (contact radius) increases, which translates into a compound cushioning effect due to the unique shape and motion of both surfaces. 
     Whenever the push button  64  is in the locked position or the latched position, the spool  22  may still rotate in a direction that causes the tether  26  to retract back into the housing  12  and be wound about the spool  22  if the leaf spring  40  has sufficient bias. This is so because the back side of each tooth  28  is ramped and the front surface  92  of the head  86  of the lock lever  78  is rounded allowing the teeth  28  to pass past the lock lever  78  by pushing the lock lever  78  up out of the way. The push button spring  74  has sufficient compression room left in order to allow such movement of the lock lever  78  despite the outer wall  68  of the push button  64  being biased against the lip  118  of the housing  12 . 
     In order to adjust the bias of the leaf spring  40 , the user pushes on the adjustment knob  46  until the ramps  58  of the adjustment knob  46  are clear of their ramp receivers  62 . The adjustment knob  46  is rotated or counter-rotated via the finger grip  56  in order to either further coil the leaf spring  40  or lesser the coil of the leaf spring  40  respectively. Once the desired tension is placed onto the leaf spring  40 , the adjustment knob  46  is released causing the ramps to once again seat within their respective ramp receivers  62  on the cover  14  via the bias of the coil spring  44 . 
     The various components of the retractable leashing with gradual braking  10  can be made from any appropriate material, such as plastic, light metal, or a combination thereof, with the various springs advantageously, though not necessarily, being made of metal 
     While the invention has been particularly shown and described with reference to an embodiment thereof, it will be appreciated by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.