Oscillator actuated hydraulic impulse device
AssigneeMitsui Engineering & Shipbuilding Co., Ltd.
InventorsTakeo Watanabe, Makoto Matsuda
Life of this patent
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Abstract
An oscillator actuated hydraulic impulse of the type including a spool valve actuated by an alternating signal from an oscillator to switch the hydraulic pressure in a double acting cylinder in order to cause reciprocating motion of a piston which strikes a boring tool. The hydraulic impulse device further includes a means for controlling the transition from the impulse stroke to the return stroke of the piston. In some embodiments, the hydraulic impulse device may further include a means for varying the duration of the impulse stroke and the return stroke of the piston.
Claims6
An oscillator actuated hydraulic impulse device of the type including a spool valve actuated by an alternating signal from an oscillator to switch the hydraulic pressure in a double-acting cylinder in order to cause reciprocating motion of a piston which strikes a boring tool and the frequency of the oscillator is independent of the movement or position of the piston, said hydraulic impulse device being characterized by:
- a rear end port provided in a rear chamber of said cylinder;
- an accumulator coupled to said rear end port;
- a flow line coupling said rear end port to a source of hydraulic fluid;
- a check valve provided in said flow line;
- a plurality of mid-point ports for controlling a transistion of said piston from an impulse stroke to a return stroke provided in said rear chamber further toward the midpoint of said cylinder than said rear end port which are opened and closed by movement of said piston;
- and
- a further flow line coupling said plurality of mid-point ports to said spool valve.
A hydraulic impulse device comprising:
- a cylinder;
- a differential piston provided in said cylinder and together with said cylinder forming a forward and rear chamber, said piston further being configured such that the area of said piston in said forward chamber is larger than the area of said piston in said rear chamber;
- a means for supplying a constant hydraulic pressure to said rear chamber;
- an oscillator whose frequency is independent of the movement or position of said piston;
- a first means for generating a signal indicative of the changed position of said piston;
- and
- a spool valve for switching hydraulic pressure into said forward chamber whereby reciprocating motion of said piston for striking a boring tool is created, said spool valve being activated in response to said oscillator and said first means.
A hydraulic impulse device comprising:
- a reciprocatable piston having an impulse stroke and a return stroke for striking a boring tool;
- an oscillator having a variable oscillating frequency which is independent of the movement or position of said reciprocatable piston for generating an alternating signal;
- a means for sensing a position of said reciprocatable piston and which generates a stroke signal when said reciprocating piston completes its impulse stroke;
- and
- a spool valve responsive to said alternating signal and said stroke signal for causing said reciprocatable piston to reciprocate whereby the transistion from said impulse stroke to said return stroke is controlled and a duration of said impulse stroke and said return stroke can be varied.
Dependencies are inferred from the claim text.