Monitoring valve, rock drilling apparatus and a method for controlling at least two hydraulic actuators to such a monitoring valve and rock drilling apparatus

A monitoring valve comprising at least:

• a body,
• an elongated slide having a first end and a second end, and arranged to a space in the body, and movable in the longitudinal direction in said space,
• at least one force element that is arranged to act on the first end of the slide to move the slide towards a first direction of travel,
• at least one controllable channel that is arranged to open and close by the longitudinal movement of the slide, and wherein
• the slide has at least one collar,
• a sleeve is arranged around the slide,
• the body has a space, inside which the collar and the sleeve are arranged to move,
• the outer rim of the sleeve is sealed to the body and the inner rim of the sleeve is sealed to the slide,
• the sleeve defines a first chamber and a second chamber on opposite sides of the sleeve, and said chambers are not connected to each other,
• the first chamber is connected at least to a first pressure channel,
• the second chamber is connected at least to a second pressure channel,
• the sleeve is arranged to move in the first or the second direction of travel depending on the pressure difference inside the chambers, and
• in one direction of travel, the sleeve is arranged to act on the axial position of the slide when abutting on the collar.

A rock drilling apparatus comprising:

• a percussion apparatus,
• a feed apparatus,
• a hydraulic system, to which the percussion apparatus and feed apparatus are connected, and at least one hydraulic pump for supplying hydraulic pressure to the hydraulic system,
• at least one compensator valve in the pressure medium channel leading to the percussion apparatus, and at least one second compensator valve in the pressure medium channel leading to the feed apparatus for adjusting the operation of the percussion apparatus and feed apparatus, respectively,
• at least one monitoring valve for setting the minimum pressure of the pressure medium led to the percussion apparatus and for adjusting the pressure of the pressure medium led to the percussion apparatus in a predefined pressure ratio with the pressure led to the feed apparatus, and wherein
• a reference pressure channel is connected to the monitoring valve and the control of the pressure in the channel is arranged to provide a specific pressure level of the feed apparatus, above which level the feed pressure activates the pressure ratio control on the percussion apparatus.

A rock drilling apparatus comprising:

• a percussion apparatus,
• a feed apparatus,
• a hydraulic system, to which the percussion apparatus and feed apparatus are connected, and at least one hydraulic pump for supplying hydraulic pressure to the hydraulic system,
• at least one compensator valve in the pressure medium channel leading to the feed apparatus for adjusting the operation of the feed apparatus,
• at least one monitoring valve for setting the minimum pressure of the pressure medium led to the percussion apparatus and for adjusting the pressure variation of the pressure medium led to the percussion apparatus in a predefined pressure ratio with the pressure variation of the feed apparatus, and wherein
• a reference pressure channel is connected to the monitoring valve and the control of the pressure in the channel is arranged to provide a specific pressure level of the feed apparatus, above which level the feed pressure activates the pressure ratio control on the percussion apparatus.