Delay unit for a projectile

Patent metadata

Field	Value
Publication number	US-11598619-B2
Application number	US-201917312586-A
Country	US
Kind code	B2
Filing date	Dec 12, 2019
Priority date	Dec 14, 2018
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

The invention relates to a method of delaying a mechanism in a firearm and a delay unit for a projectile comprising i) a first and a second pressure chamber ( 3 a, 3 b ) arranged to receive combustion gases in a firearm via at least one inlet ( 1 a, 1 b ) arranged to each of said first and second pressure chambers ( 3 a, 3 b ) following firing of a projectile ii) at least one outlet for transferring the combustion gases ( 4 a, 4 b ), arranged to each of said first and second pressure chambers ( 3 a, 3 b ), to a piston chamber in which a displaceable piston ( 6 ) is arranged dividing the piston chamber into a compartment ( 5 b ) having a volume V 1 upstream the piston ( 6 ) and a compartment ( 5 a ) having a volume V 2 downstream the piston ( 6 ), wherein said at least one outlet ( 4 a, 4 b ) from the first and second pressure chambers ( 3 a, 3 b ) are arranged to transfer said combustion gases to said compartments ( 5 a, b ) of said piston chamber to provide an overall pressure difference between compartments ( 5 a ) and ( 5 b ) pressing the piston ( 6 ) at an initial idle position downstream whereby the volume V 2 of compartment ( 5 a ) is reduced and whereby the piston ( 6 ) being pressed downstream towards an end position actuates a function at a predetermined point in time following firing of a firearm.

First claim

The invention claimed is:

1. Delay unit for a projectile, the delay unit comprising:
a first and a second pressure chamber ( 3 a , 3 b ) each configured to receive combustion gases in a firearm via at least one inlet ( 1 a , 1 b ) arranged to each of said first and second pressure chambers ( 3 a , 3 b ) following firing of a projectile; and
at least one outlet for transferring the combustion gases ( 4 a , 4 b ), arranged to each of said first and second pressure chambers ( 3 a , 3 b ), to a piston chamber in which a displaceable piston ( 6 ) is arranged dividing the piston chamber into a compartment ( 5 b ) having a volume V 1 upstream the piston ( 6 ) and a compartment ( 5 a ) having a volume V 2 downstream the piston ( 6 ),
wherein:
the outlets ( 4 a , 4 b ) from the first and second pressure chambers ( 3 a , 3 b ) are configured to transfer said combustion gases to said compartments ( 5 a , 5 b ) of said piston chamber to provide an overall pressure difference between compartments ( 5 a ) and ( 5 b ) pressing the piston ( 6 ) at an initial idle position downstream,
whereby the volume V 2 of compartment ( 5 a ) is reduced, and
whereby the piston ( 6 ) being pressed downstream towards an end position actuates a function at a predetermined point in time following firing of the firearm.

2. Delay unit according to claim 1 , wherein a resilient means is configured to maintain the piston ( 6 ) immovable at an initial idle position prior to establishing a pressure difference between compartments ( 5 a , 5 b ).

3. Delay unit according to claim 1 , wherein the piston ( 6 ) in said initial idle position is configured to block flow of combustion gases from the piston chamber via an opening ( 8 ) between the piston chamber and a sub-chamber ( 9 ).

4. Delay unit according to claim 3 , wherein the sub-chamber ( 9 ) is provided with a displaceable sub-chamber piston ( 10 ) configured to be displaced from an initial idle position when exposed to flow of combustion gases originating from the piston chamber.

5. Delay unit according to claim 1 , wherein said inlets of the first and second pressure chambers ( 3 a , 3 b ) each have an area ranging from 0.1 to 50 mm 2 .

6. Delay unit according to claim 1 , wherein at least one outlet is arranged to at least one of said first and/or second pressure chambers ( 3 a , 3 b ) for evacuating a predetermined portion of said combustion gases outside of the delay unit.

7. Delay unit according to claim 1 , wherein the outlets for transferring combustion gases ( 4 a , 4 b ) to the piston chamber are arranged at the opposite side of the pressure chambers relative to the inlets ( 1 a , 1 b ).

8. Delay unit according to claim 1 , wherein the piston ( 6 ) is configured to be displaced from an initial idle position downstream to an end position such that an opening ( 8 ) between the piston chamber and a sub-chamber ( 9 ) is unblocked.

9. Delay unit according to claim 1 , wherein:
a sub-chamber piston ( 10 ) is configured to break a short circuit comprising a piezoelectric sensor following actuation of the sub-chamber piston ( 10 ),
the sub-chamber piston ( 10 ) is configured to be actuated by the combustion gases which flows into the sub-chamber as the opening ( 8 ) is unblocked, and
as the combustion gases enter the sub-chamber, the sub-chamber piston is configured to be pressed downstream from its initial position to an end position in analogy with the piston ( 6 ) of the piston chamber.

10. Delay unit according to claim 6 , wherein the outlet for evacuating combustion gases has a length ranging from 1 to 50 mm.

11. Delay unit according to claim 1 , wherein the outlet of each pressure chamber ( 4 a , 4 b ) for transferring combustion gases has an area ranging from 0.5 to 50 mm 2 .

12. Delay unit according to claim 1 , wherein a fuse is connected to the delay unit.

13. Delay unit according to claim 1 , wherein a piezoelectric sensor is connected to the delay unit.

14. Delay unit according to claim 9 , wherein the sub-chamber piston ( 10 ) is configured to break a short circuit comprising a piezoelectric crystal following actuation of the sub-chamber piston ( 10 ).

15. Method of delaying a mechanism for a projectile in a firearm comprising the delay unit according to claim 1 , the method comprising the steps of:
receiving combustion gases by the first and the second pressure chamber ( 3 a , 3 b ) in a firearm via the at least one inlet ( 1 a , 1 b ) following firing of a projectile, and
transferring the combustion gases, via the at least one outlet ( 4 a , 4 b ), to the piston chamber,
wherein the transferring of the combustion gases to the piston chamber provides the overall pressure difference between the compartments ( 5 a ) and ( 5 b ) pressing the piston ( 6 ) at the initial idle position downstream whereby the volume V 2 of the compartment ( 5 a ) is reduced and whereby the piston ( 6 ) being pressed downstream towards the end position actuates the function at the predetermined point in time following the firing of the firearm.

16. Use of a delay unit according to claim 1 for delaying premature detonation of a warhead.

Assignees

• Saab Ab

Inventors

• Carlsson Michael
• Runemård Mats
• Fohrman Erik
• Englund Owe

Classifications

• F42C11/02

  with piezo-crystal · CPC title

• F42C15/30 Primary

  of propellant gases, i.e. derived from propulsive charge or rocket motor · CPC title

• F42C15/005

  Combination-type safety mechanisms, i.e. two or more safeties are moved in a predetermined sequence to each other · CPC title