Ordnance – Breech closures – Gas checks
Patent
1992-12-07
1994-04-26
Brown, David H.
Ordnance
Breech closures
Gas checks
F41A 374, F41A 376, F41A 977
Patent
active
053056795
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a cylinder mortar of the type in which a gun barrel is associated with an ammunition cylinder mounted to rotate about an axis parallel to the axis of the barrel. The mortar includes a plurality of cylindrical chambers for receiving rounds of ammunition, open at their front and rear ends and each movable by rotation of the cylinder to a firing position aligned with the barrel. The rear end of the mortar then being supported on a firing plate including means for firing the ammunition.
Mortars of this type are generally fitted to armored vehicles and allow a relatively high rate of fire, thanks to the cylinders whose chambers can easily be reloaded with ammunition during firing and which also enable rapid burst firing when all the chambers of a cylinder have been preloaded.
However, the rotation of the cylinder which enables the chambers to be brought into firing position in turn, i.e. into alignment with the barrel and supported on the firing plate with the means for firing the ammunition, requires high dimensional accuracy of the parts in question and use of more or less complex means to ensure gas tightness during firing, while allowing rapid rotation of the cylinder and loading the chambers through their front ends.
SUMMARY OF THE INVENTION
An object of the invention is to overcome these problems using means of simple structure.
To this end, the invention provides a cylinder mortar of the type defined above which is characterized in that each chamber includes at its rear end elastically deformable means forming an abutment for supporting and positioning the rounds of ammunition inserted in the chamber through the front end thereof and further ensuring gas tightness on firing, relative to the chamber and to the firing plate.
The elastic deformation of the aforesaid means caused by the propellant gas pressure during firing makes complete sealing between the chamber and the firing plate possible. Moreover the weight of the round loaded into the chamber enables these means to be elastically supported with gentle pre-stressing on the firing plate when the chamber is brought into firing position.
In a preferred embodiment of the invention, these means are constituted by a metal seal of generally cylindrical shape, open at the front and having an annular bottom wall at the rear end with a central aperture, this seal being mounted in a bore in the rear end of the chamber and retained in this bore by means such as a screw retainer.
This cylinder seal is slidably mounted, without radial play, in the bore of the chamber and has a ground cylindrical outer surface with a diameter equal to the diameter of the bore of the chamber.
The sliding fit of the seal in the chamber, without play, compensates for the variations in the manufacturing dimensions of the chambers, without impairing sealing. The grinding of the contacting cylindrical surfaces of the seal and the chamber further avoids metal-metal inclusions when firing, which would jam the seal in the chamber and prevent its normal operation.
According to another feature of the invention, the inner surface of the seal is cylindrical with a circular cross-section in the vicinity of the bottom wall, with a diameter ensuring that ammunition is centered, and is flared over its front part, the wall thickness of the seal tapering towards its front end.
This inner flared surface is intended to facilitate loading and positioning of a round of ammunition in the chamber and also to facilitate the elastic deformation of the corresponding part of the seal. The corresponding part is supported by the bore of the chamber to ensure sealing under the action of the gas pressure during firing.
According to another feature of the invention, the outer surface of the bottom wall of the seal is slightly coned, its smaller base forming the aforesaid central aperture and protruding from the bottom of the seal.
The inner surface of the bottom wall of the seal comprises an annular part lying in a plane perpendicular to the axis of the seal a
REFERENCES:
patent: 3403596 (1968-10-01), Bartels
patent: 3420139 (1969-01-01), Bartels
patent: 3783737 (1974-01-01), Ashley
patent: 4709616 (1987-12-01), Bartoiles
patent: 5054366 (1991-10-01), Bartolles
patent: 5147971 (1992-09-01), Bartolles
Brown David H.
Giat Industries
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