Patent ID: 11859450
Assignee: SICHUAN UNIVERSITY
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 5:
6. The drilling fluid channel structure of a core drilling rig according to claim 3, wherein the pressure relief module comprises a connecting pipe and a lock pin, a front end of the connecting pipe is connected to the lock housing, and a rear end of the connecting pipe is connected to the lock body, wherein a rear end of the lock pin is connected to the locking rod, the rear section of the central rod extends through the inner cavity of the lock pin disposed in the connecting pipe,
wherein a fluid channel C is arranged between the rear section of the central rod, the lock pin, and the locking rod,
a side wall of the locking rod is provided with an inflow hole, and the fluid channel B and the fluid channel C are communicated through the inflow hole, the fluid channel C fluidly communicates with the fluid channel D,
wherein the connecting pipe comprises a pressure relief section and a flow blocking section, and the lock pin is in a sealing fit with the flow blocking section,
wherein an inner diameter of the flow blocking section is smaller than that of the pressure relief section, the pressure relief section is provided with a pressure relief hole, which is a through hole,
wherein a shearing plunger is disposed in the fluid channel B, and an inner diameter of the shearing plunger is larger than an outer diameter of the lock pin and the locking rod,
wherein the shearing plunger is connected to the lock body through an end shear pin, the shearing plunger comprises a shearing section and a recoil section, an outer wall of the shearing section is in a sealing fit with the inner wall of the lock body, and the outer diameter of the recoil section is equal to the inner diameter for the front part of the pressure-relief hole in the pressure-relief section,
during operation, before drilling stops, the front end of the recoil section is in front of the front end of the pressure-relief hole, and the recoil section is in a sealing fit with the front part of the pressure-relief hole in the pressure-relief section; and, after drilling stops, liquid backflow impacts the front end of the shearing plunger, and the shearing plunger moves backward, the front end of the recoil section is disposed behind the front end of the pressure-relief hole, and the fluid channel B communicates with the pressure-relief hole.