US 12,404,725 B2
Valve cylinder, impact device and method
Juha Polonen, Tampere (FI); Jarkko Niemi, Tampere (FI); and Timo Kela, Tampere (FI)
Assigned to Sandvik Mining and Construction Oy, Tampere (FI)
Appl. No. 18/714,608
Filed by SANDVIK MINING AND CONSTRUCTION OY, Tampere (FI)
PCT Filed Dec. 2, 2022, PCT No. PCT/EP2022/084165
§ 371(c)(1), (2) Date May 30, 2024,
PCT Pub. No. WO2023/099716, PCT Pub. Date Jun. 8, 2023.
Claims priority of application No. 21212280 (EP), filed on Dec. 3, 2021.
Prior Publication US 2025/0027368 A1, Jan. 23, 2025
Int. Cl. E21B 1/38 (2006.01); B25D 9/20 (2006.01); E21B 1/26 (2006.01)
CPC E21B 1/38 (2020.05) [B25D 9/20 (2013.01); E21B 1/26 (2020.05); B25D 2209/005 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A valve cylinder for a hydraulic impact device of a rock breaking apparatus, the valve cylinder comprising:
an elongated piece having a central axis, a front end and a rear end;
a central opening extending from the front end to the rear end, and through which central opening a percussion piston mountable;
at least two pressure spaces limited by radial surfaces of the central opening and being located at an axial distance from each other; and
a plurality of axial pressure fluid channels connecting the at least two pressure spaces, wherein one of the at least two pressure spaces is a control pressure space located at the rear end of the valve cylinder and is configured to receive a sleeve-like control valve, wherein the control pressure space is provided with an inner radial groove including a bottom surface defining a radial extension of the inner radial groove in relation to the central opening adjacent the inner radial groove, and wherein the axial pressure fluid channels pass the inner radial groove without fluid connection with the inner radial groove, the inner radial groove having minimum radial dimensions at portions of the axial pressure fluid channels and maximum radial dimension at intermediate sections located between the axial pressure fluid channels, whereby a size of the inner radial groove is increased when compared to a simple groove with a circular bottom surface corresponding to the minimum radial dimensions at the portions of the axial pressure fluid channels.