Plant protector

Details Plant protector Plant protector

2001-11-28

2003-12-02

Payer, Hwei-Siu (Department: 3724)

Cutlery

Cutting tools

With blade moving means

C030S286000

Reexamination Certificate

active

06655034

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a string trimmer and in particular to a mechanism for shielding plants from the cutting path swept out by the rotating cutting line of the string trimmer.
BACKGROUND OF THE INVENTION
SUMMARY OF THE INVENTION
String trimmers are portable hand-held outdoor gardening power tools, used for domestic and commercial grass cutting and are powered by electrical motors or small combustion engines. A string trimmer has a cutting head from which extends a cutting line, the cutting line commonly being a flexible plastic wire. The cutting line extends radially from the axis of rotation of the cutting head when it is rotatably driven by a motor. In the usual cutting mode, the cutting head and cutting line rotate a high rotational speed about an approximately vertical axis. The rotating cutting line is placed in close proximity to the grass to be cut. The grass caught within the path swept out by the rotating cutting line is severed when impacted by the cutting line.
This method of cutting grass is quick and highly effective and can be employed in dense grass or on a household lawn.
Indiscriminate cutting of soft vegetation may not be a problem when cutting in certain locations. However, the string trimmer may be used in a location where there is a mixture of soft vegetation where some parts need to be cut and other parts need to be left. One example is where the verge of a lawn abuts a flower bed containing small and delicate flowers which overhang the grass. In this example a string trimmer cannot be used easily to cut the grass without damaging overhanging flowers that are also caught in the path swept out by the rotating cutting line.
The example cited above illustrates a situation when the user wishes to protect certain plants from the rotating cutting line. There are, however, instances when the user wishes to protect the rotating cutting line from coming into contact with hard objects that the cutting line was not intended to cut, such as rocks or stones. When the rotating cutting line makes contact with such objects, it is liable to be damaged and therefore would need to be replaced. This situation is also undesirable and a device which protects certain plants from the rotating cutting line should also be capable of protecting the rotating cutting line from damaging itself against hard objects.
Prior art document EP 0 893 050 discloses a length of rigid metal wire attached to and extending outwardly from the motor housing of a string trimmer and is adapted to form a guard surrounding part of the path swept out by the rotating cutting line. EP 0 893 050 further discloses that the wire can also act as an edging guide. When acting as an edging guide, the rotating cutting line can cut a uniform edge along a lawn edge or a curb without coming into contact with the lawn edge or curb.
However, there are two problems associated with the guard disclosed in EP 0 893 050. The metal wire, when acting as a guard, does not surround the path swept out by the rotating cutting line. This leaves ample space for vegetation, such as overhanging plants or flowers, to enter into the path swept out by the rotating cutting line which results in damage to this vegetation.
Secondly, when the string trimmer is used in edging mode, the metal wire acts as a guide and therefore is unable to act as a guard. As such no protection is provided against cutting vegetation which is not intended to be cut.
Accordingly, there is provided a string trimmer comprising an elongate shaft; a cutting head rotatably mounted on one end of the elongate shaft at least one cutting member which extends from the cutting head on a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member when it rotates characterised in that the barrier is in the form of a broad band.
By constructing the barrier in the manner the broad band is able to act as a shield by which the vegetation is protected from the rotary line. By utilising a broad band, the barrier has a large surface area which can make contact with the vegetation when an operator uses the barrier to prevent vegetation entering the path of the rotating cutting member the large surface area of the barrier makes contact with the vegetation. Therefore, the same pressure can be applied to vegetation to move it whilst allowing the force to be exerted over a greater area on the vegetation thereby less likely to result in damage to the vegetation.
Furthermore, the use of a broad band ensures that the vegetation is less likely to pass the barrier and enter the path swept out by cutting member.
Furthermore, the lightweight plant protector can be rotatably moved between a plurality of angular positions without the need of dismantling any part of the string trimmer. When in use, a primary function of the plant protector is to provide a barrier between overhanging plants and the path swept out by the rotating cutting line, while still allowing low level vegetation like for example grass, to pass below the lower edge of the plant protector and into the path of the rotating cutting line. The plant protector has two ‘in-use’ positions; one position for flat cutting and, the other for vertical edge trimming, such that when located in both ‘in-use’ positions the lower edge of the plant protector is approximately horizontal when the string trimmer is used in the appropriate way. The truncated spherical shell shape formed by the outer surface of the plant protector extends upwardly and arcuately from its lower edge. This outer surface provides a barrier which pushes away any overhanging plants from the path of cutting field as the string trimmer advances towards them. While protecting overhanging plants from rotating cutting line, the plant protector also protects the rotating cutting line from unnecessary contact with hard objects, like for example stone, which can damage and shorten the life span of the cutting line.


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