GB2264219A

GB2264219A - Dog restraint system.

Info

Publication number: GB2264219A
Application number: GB9222120A
Authority: GB
Inventors: William Alexander Courtney
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-02-22
Filing date: 1992-10-21
Publication date: 1993-08-25
Anticipated expiration: 2012-10-21
Also published as: GB9203845D0; GB9222120D0; GB2264219B

Abstract

An elastic dog leash comprises an elastic material 1 an outer sheath 2. The leash also can also include energy absorbing devices which significantly reduce the impulse force caused when the dog makes a sudden movement. A second handle attached part way along the leash offers short leash control when necessary. An associated problem experienced with long leashes is that they have a tendency to become tangled with the dogs legs. The invention described can be extended to include elasticated harnesses which position the leash above the dogs body such that the leash is less likely to become tangled with the animals legs. <IMAGE>

Description

Dog Restraint System This invention relates to devices for restraining dogs or other animals when walking or otherwise accompanying them. Existing dog leashes on the market fail into two categories: fixed length leashes and longer leashes which retract into a holder. Both types cause a considerable force to be exerted on the animal and the controller when the animal makes a sudden movement. This force has two components, a semi-static component equal and opposite to the force exerted by the animals claws as it grips the ground and moves away, along the line of the leash and a dynamic component caused by the change in momentum as the moving animal is decelerated, as the leash is brought under tension.The longer leashes are designed to offer the animal greater freedom of movement, however this also means that the animal can acquire a greater velocity before it moves a sufficient distance to bring the leash to a state of tension. Consequentially there is an even larger dynamic component to the force on the dog and the controller. A second problem experienced with long leashes is that they have a tendency to become tangled with the dogs legs. The invention to be described will significantly reduce the magnitude of the dynamic component of the force and reduce the number of occasions on which longer leashes become entangled with the animals legs.

The principle involved in reducing the dynamic component of the force is to increase the time taken for the momentum of the moving animal to be reduced to an acceptable level. This is in accordance with the laws of Newtonian mechanics. A lead or leash with elastic or visco-elastic properties satisfies this requirement.

In order to reduce the occasions on which the leash tangles the animals legs the leash can be attached to a harness which moves the point at which the leash breaks away from the animals body to a point along the back of the animal, approximately above the spine.

Specific embodiments of the system will now be described.

The main length of the leash consists of an elastic cord or the like which can be attached at its ends to the inside of a sheath of relatively inelastic material which has been chosen to cope with the forces exerted by an energetic dog of a given size. The natural length of the elastic material is less than that of the sheath.

Consequentially in the unstressed situations the outer sheath is concertinared.

The length of the elastic material is chosen so that it is within its elastic limit when the sheath is fully extended.

In the basic design the leash is completed by the addition of a conventional handle or handle loop and a clip for attaching to the dogs collar or choker or the like. In figure 1, 1 is the elastic material, 2 is the outer sheath, 3 the handle and 4 the attachment clip. When the animal moves so that the length of the leash increases the Hooke's law force also increases in the leash, opposing the increase in the animals velocity.

The materials and their lengths can be chosen so that the force required to fully extend the leash is not sufficient to cause discomfort to the controller or animal.

This allows the dog to enjoy the freedom benefits of a comparatively long leash.

Figure 2 shows a core which consists of 2 which is a short length of low elastic constant, high elastic limit material connected to the ends of 1 which has a significantly larger elastic constant. This series combination helps to reduce the relaxed length of the leash compared with its fully stretched length.

Fig 3 shows an alternative combination of an elastic material, 2 with a length of relatively inelastic material, 1. In this example a long rectangular length of elastic material is stretched before its edges are bonded to the inelastic material by sowing, riveting or the like. End corner 3 of the elastic material has been stretched slightly more than end corner 4 before bonding. As a consequence when the materials are allowed to relax on the removal of the stretching forces the leash acquires a spiral shape, this effectively reduces the relaxed length of the leash allowing a long stretched leash to contract to a convenient short length when relaxed An alternative design which produces a similar effect is to bond a length of stretched elastic material to the edge or close to the edge of the width of the relatively inelastic material for all or part of its length.

Figures 4 and 5 show the preferred version of the elastic leash. Figure 4 is a plan view, along the length of the leash, prior to final tensioning and figure 5 is a cross sectional view. In both figures 1 is the essential load bearing leash material. 2 is a channel in which an elastic cord, 3 is retained. The elastic cord is stressed before being anchored to the ends of the load bearing material.

The channel is asymmetricaly bonded across the width of the load bearing material. Consequentially the leash relaxes to a shortened spiral form in order to minimise its potential energy.

A disadvantage of a long leash is that the animal controller may experience difficulty in retaining close control in a busy environment. This is overcome with the present invention by attaching a second handle part way along the leash.

Figure 6 shows a variation which consists of the addition of a short length of elastic material, 1 which has a significantly larger elastic constant than the elastic cord. This is beneficial for further reducing the dynamic component of the force for fast moving massive animals. This elastic material could for example take -the form of a helical spring or block of elastic material or one which has visco-elastic properties such as Sorbothane.

Figure 7 shows an energy absorbing spring device which can be added with benefit to the leash. This device is a small cylinder which can be attached for example at the end of the leash before the clip.'A helical spring, 1 is retained inside a cylinder 2. Rings 4 and 5 can be used to connect the device to the end of the leash and the clip. 3 is a piston which compresses the spring when tensile forces act on 4 and 5. The natural length of the spring can be in excess of the length of the cylinder so that it is always subject to a compressive force.

This has the consequence that small tensile forces which stretch the main length of the leash do not cause further compression of the spring so that if the system parameters are chosen correctly the device takes over the task of absorbing the impulse energy of the moving dog after the leash has stretched to its full length.

Figure 8 shows a visco-elastic damper which is a modification of the design illustrated in figure 7. This is similar to a traditional damper as known to those familiar with the arts of energy absorbing systems but is modified by the addition of one or more valves, 1 which allow the damping fluid to flow with relative ease in one direction. This allows the damper to offer considerable opposition to movement of the dog away from the controller but rapid contraction of the damper when the dog ceases to pull. The merit of including a fluid damper is that the resistive force offered by the damper is a function of the velocity with which the piston moves down the cylinder, which in turn is a function of the velocity of the dog.

Figure 9 is similar to figure 8 but illustrates a damper which includes a skirt attached to the piston. This offers protection from the environment and reduces the stress on the shaft of the piston if it is subject to transverse forces.

The leash may be modified in several ways to increase its range of uses. The handle may incorporate a whistle and include a small storage pocket.

The elastic properties of the present invention make it particularly suitable for attaching the controllers end to an item of clothing, for example a belt instead of the controller holding the leash. In order to facilitate the ease of tethering the handle may be fitted with a clip which allows the leash to be joined back to itself after being looped around a tethering point.

Figure 10 shows a harness made from elasticated material. The harness consists of a loop which is closed by a standard closing device such as a buckle or the like and encompasses the trunk of the dog behind its front legs. A strap attached at appropriate points on the loop crosses the breast of the animal and prevents rotation of the loop around the trunk. The leash or free end of the choker is threaded through a small loop or the like attached to the top of the main loop. The function of this design is to ensure that the point at which the leash comes away from the dogs body is approximately above the neck and therefore unlikely to become tangled with the dogs legs, provided that the leash is maintained under a gentle tension.

Figure 11 shows an additional loop which encompasses the rear half of the dogs trunk in front of the back legs. This loop is prevented from moving foreword by attaching two straps which encompass the rear legs. For comfort and a snug fit the loop and straps are made from elasticated materials. An elasticated extension from the top of this rear loop encompasses the leash or free end of the choker, bringing the point at which the leash comes away from the body further along the back of the dog, above the spine than when using the front harness alone. This design further decreases the chances of the leash becoming tangled with the dogs legs.

Claims

1 A dog or other animal leash which is appreciably elastic for all or part of its length.

2 A dog or animal leash which in order to achieve its elasticity is constructed for all or part of its length having an outer sheath and an elasticated core such that the effective length of the leash increases when tensile forces are applied to the ends.

3 As for claim 2 but with the core consisting of two or more lengths of elastic material in series.

4 As for claim 2 but with the core consisting of two or more lengths of elastic material in parallel.

5 As for claims 3 or 4 with the lengths having different natural lengths.

6 As for claims 3 or 4 with the lengths having different elastic constants.

7 An leash which incorporates features as in the above claims but which has an elasticated sheath and a relatively inelastic core.

8 A leash which incorporates features as in the above claims but which has an elasticated material flexibly bonded to a relatively inelastic material such that the inelastic material effectively contracts in length when the leash is unstressed by extending forces.

9 As for claim 8 but with the materials so attached that the unstressed leash relaxes into the form of a spiral or helix.

10 As for claim 8 but with the elastic material attached to the relatively inelastic material such that the tension on one half of the width or edge of the inelastic material is greater than for the other half for all or part of its length so that the unstressed leash relaxes into the form of a spiral or helix.

11 A leash as in the above claims which includes a second handle attached at a point along the length of the leash.

12 A leash as in the above claims which includes one or more spring or visco-elastic dampers that act so as to reduce the impulse when the animal makes a rapid movement which increases the tensile force on the leash.

13 A leash as in the above claims which includes a visco-elastic damper which includes a one way valve or other device which allows the damping fluid to flow with reduced opposition in one direction. This design allowing the damper to offer damping effects of different magnitudes on expansion or contraction of the length of the damper.

14 A leash as in any of the above claims which includes a visco-elastic damper as for claim 13 which includes an external cover or skirt which is attached near the external end of the piston and extends over all or part of the main body of the damper which holds the damping fluid.

15 A leash as in any of the above claims which includes one or more visco elastic dampers that is designed such that the viscous forces opposing motion are greater when the leash is subject to extending forces than when the leash is contracting in length as the force is reduced.

16 A leash as in any of the above claims which includes a whistle as an integral part of the leash.

17 A leash as in any of the above claims which includes a storage compartment as an integral part of the leash.

18 A leash as in any of the above claims which is attached to an elasticated harness which encompasses the front legs and breast of the animal and has a loop which helps to maintain the end of the leash approximately above the animals spine, thereby reducing the likelihood of the leash becoming entangled round the legs of the animal.

19 As for 18 with a modification to the harness consisting of an elasticated part which encompasses the rear half of the animals trunk and moves the point at which the leash comes away from the body further back along the spine than the neck.

20 As for claims 18 or 19 but including adjustment devices attached to the harness to cater for different sizes and/or shapes of dogs.

21 A leash as in any of the above claims which includes a clip that enables the leash to be rejoined to itself after being threaded round an anchor point.

22 A leash or harness system as described in any of the above claims which is applied to humans.