Latch

Details Latch Latch

1995-08-29

1998-03-31

Lindsey, Rodney M.

Closure fasteners

Bolts

Hooked end

292247, E05C 1912

Patent

active

057329877

DESCRIPTION:

BRIEF SUMMARY
This invention relates to latches of the type used to latch together two parts of an item, such as the lid and body of a container.
There are many forms of latch which have been used for a number of years for closing and sealing functions. Such latches, whilst being cheap and simple to manufacture often have the problem that they require manual operation to be closed and do not provide an indication to the user when they are not in a fully latched state.
An example of such a latch would be the toggle type which comprises a first lever attached to an item, and a second lever which pivots on the first lever, engages with a latching surface, and locks in an over-centre pivot action. Such latches are cheap to manufacture, simple to use and reliable even in harsh environments. These latches do, however, have the problem that it is difficult to determine when they are securely latched and that they can, occasionally, be jarred open by vibrations.
Attempts have been made to overcome these problems by provision of either a slide type secondary lock with a catch moving axially in the latch's lever, or by a spring catch type mechanism, where a steel latch engages from the base through the lever to latch. Both of these solutions can suffer from corrosion or jamming from dirt entering the mechanism and often have a "cheap" feel to their operation. Automatically closing latches are also available, but do not generally provide a strongly sealed closure and are vibration sensitive.
There is a need therefore for a latch which closes automatically to provide a safe and secure closure but which may also provide a tight, vibration resistant closure. There is also a need to provide a latch which provides an indication that it is fully closed.
According to the present invention a latch comprises: strike block when the first and second members come into contact; with the strike block; support block, to retain the latch in a latched position; and, block when the second lever is in its engaged position.
Because the first lever automatically engages with the strike block, the two members will be latched even if the user does not bring the second lever into engagement, thus ensuring that the item is always safely fastened on engagement of the two members.
Also, as the third lever is biased into engagement with the support block, the latch will not be jarred free by vibration or accidental snagging and, since the third lever must be depressed prior to the latch being released, accidental opening of the latch is unlikely.
The strike block may comprise two components, the first of which engages with the first lever, and the second of which is adjustably mounted on the first to provide an adjustable engagement with the second lever.
The biasing means may be a spring or a combination of springs, and may also act to bias the second lever into a warning position when it is not fully engaged and/or bias the first lever towards an engaging position.
The second lever is preferably biased to a position in which it "flags" the fact that the latch is not engaged, ie the free end of the second lever projects outwardly from the latch.
Advantageously, there is a common biasing means for the second lever and the third lever. The biasing means will usually be a spring, which can be attached to the support block or first lever at one end and attached to the third lever at its other end. The biasing means may, however, be a torsion spring attached to the third lever and in engagement with the first lever, the second lever or support block to bias the third lever toward an engaged position.
Because the third lever engages with the support block when the latch is in a closed position, the latch provides a more secure fixing, which is less likely to become disengaged during excessive vibration of the latch assembly. Also, as the third lever must be released before the latch will disengage, there is a reduced possibility of the latch being opened accidentally.
Examples of a latches according to the present invention will now be described with reference to

REFERENCES:
patent: 3394955 (1968-07-01), Martin
patent: 3630559 (1971-12-01), Rawson et al.
patent: 4493133 (1985-01-01), Nilsson

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