# US 5,707,176 A · Earth discharge control system for small-diameter pipe propelling machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,176 A - Document ID: US5707176A - Status: Granted - Kind: A - Application number: 08/582,999 - Filed: 1995-12-01 - Granted: 1998-01-13 - Earliest claimed: 1993-05-14 - Assignees: Kabushiki Kaisha Komatsu Seisakusho - Inventors: Yasuo Okubo - Web page: https://patentgrep.com/patent/US5707176A ## CPC - E21B 44/00: Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions - E21B 7/005: {with helical conveying means (E21B7/201 takes precedence; augers E21B10/44; drilling rods or pipes with helical structure E21B17/22)} - E21B 7/201: {with helical conveying means} - E21D 9/108: {Remote control specially adapted for machines for driving tunnels or galleries (for machines for slitting or completely freeing the mineral E21C35/24)} - E21D 9/124: {Helical conveying means therefor (E21D9/13 takes precedence)} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - E21D: SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS (soil-conditioning or soil-stabilising materials C09K17/00; drilling or cutting machines for mining or quarrying E21C; safety devices, transport, rescue, ventilation or drainage E21F) ## Abstract An earth discharge control system for a small-diameter pipe propelling machine controls the excavated earth discharging operation of the small-diameter pipe propelling machine. The small-pipe propelling machine propels a small-diameter pipe (2) joined at its leading end to a leading pipe (1) into the ground by a propelling unit (3) installed in a starting shaft (4). Earth excavated by a cutting head (8) supported on the leading end of the leading pipe (1) is conveyed toward the starting shaft (4) by a screw conveyor (6) disposed within the small-diameter pipe (1). A pneumatically operated control valve (10) is disposed in combination with a portion of the screw conveyor (6) within the leading pipe (1). A pressure detector (23) detects the pressure in the pressure chamber (10a) of the control valve (10) and the amount of excavated earth contained in a portion of a casing (6b) extending ahead of the control valve (10) is estimated on the basis of the pressure in the pressure chamber (10a) of the control valve (10). The rotation of the screw shaft (6a) of the screw conveyor (6) is controlled on the basis of information thus acquired so that an optimum amount of excavated earth is taken always into the screw conveyor (6). ## Claims ### Claim 1 An earth discharge control system for a pipe propelling machine for positioning a small-diameter pipe in the ground, the small-diameter pipe having a front end, the pipe propelling machine having: a leading pipe positioned against the front end of the small-diameter pipe; a propelling unit positionable in a starting shaft for moving the small-diameter pipe and the leading pipe forward; a screw conveyor disposed in the leading pipe for transporting earth rearwardly towards the starting shaft, said screw conveyor including a rotatably mounted screw shaft and a hydraulic drive unit connected to the screw shaft for rotating the screw shaft, said hydraulic drive unit being configured to rotate the screw shaft at a variable screw shaft speed; and a pneumatically operated control valve located within the leading pipe for regulating rearward movement of earth along the screw conveyor, said control valve including a valve element with an expandable pressure chamber that is inflated to a set pressure and a pressure detector for monitoring the pressure in the pressure chamber, said pressure detector generating a pressure-sensed signal representative of the pressure in the pressure chamber; comprising the improvement wherein said control system comprises: processor means connected to the pressure detector for receiving the pressure-sensed signal and connected to the hydraulic drive unit for controlling the hydraulic drive unit so as to regulate the screw shaft speed, said processor means being configured to calculate a pressure difference between the set pressure of the pressure chamber and the actual pressure of the pressure chamber as indicated by the pressure-sensed signal and to control the hydraulic drive unit so as to regulate the screw shaft speed based on the calculated pressure difference. ### Claim 2 (depends on 1) The earth discharge control system according to claim 1, further including a pressure regulating valve in communication with the pressure chamber and a servomotor connected to the pressure regulating valve for controlling the state of the pressure regulating valve, and wherein said processor means is connected to said servomotor for controlling said servomotor so as to adjust the set pressure of the pressure chamber. ### Claim 3 (depends on 1) The earth discharge control system according to claim 1, wherein said hydraulic drive unit includes a hydraulic motor which drives the screw shaft and a hydraulic pump which supplies a working fluid to the hydraulic motor, and wherein said processor means is connected to the hydraulic pump for controlling the rate of fluid discharge from the hydraulic pump so as to regulate the speed of the screw shaft to maintain the calculated pressure difference within a set control range. ### Claim 4 A pipe propelling machine for positioning a small-diameter pipe in the ground, the small-diameter pipe having a front end, the pipe propelling machine comprising: a leading pipe positioned against the front end of the small-diameter pipe, the leading pipe having a front end that is positioned forward of the front end of the small-diameter pipe; a propelling unit for moving the small-diameter pipe and the leading pipe forward; a screw conveyor disposed in the leading pipe for transporting earth rearwardly from the front end of the leading pipe, said screw conveyor including a rotatably mounted screw shaft and a drive unit connected to the screw shaft for rotating the screw shaft, said drive unit being configured to rotate the screw shaft at a variable screw shaft speed; and a pneumatically operated control valve located within the leading pipe, said control valve including a valve element for regulating movement of earth along the screw conveyor, said valve element having an expandable pressure chamber that is inflated to a set pressure; comprising the improvement wherein a control system is provided for regulating the discharge of earth from the leading pipe, said control system including: a pressure detector in fluid communication with the pressure chamber for monitoring the pressure of the pressure chamber and being configured to generate a pressure-sensed signal representative of the pressure in the pressure chamber; and processor means connected to said pressure detector for receiving the pressure-sensed signal and connected to the drive unit for controlling the drive unit so as to regulate the screw shaft speed, said processor means being configured to calculate a pressure difference between the set pressure of the pressure chamber and the actual pressure of the pressure chamber as indicated by the pressure-sensed signal and to control the drive unit so as to regulate the screw shaft speed based on the calculated pressure difference. ### Claim 5 (depends on 4) The pipe propelling machine according to claim 4, wherein said processor means is configured to compare the calculated pressure difference to a first control value and cause the drive unit to increase the screw shaft speed if the calculated pressure difference is less than the first control value, and to compare the calculated pressure difference to a second control value and cause the drive unit to decrease the screw shaft speed if the calculated pressure difference is greater than the second control value. ### Claim 6 (depends on 4) The pipe propelling machine according to claim 4, including a pressure regulating valve in communication with the pressure chamber and a servomotor connected to the pressure regulating valve for controlling the state of the pressure regulating valve and wherein said processor means is connected to said servomotor for controlling said servomotor so as to adjust the set pressure of the pressure chamber. ### Claim 7 (depends on 4) The pipe propelling machine according to claim 4, wherein said drive unit is a hydraulic drive unit having a hydraulic motor connected to the screw shaft for rotating the screw shaft and a hydraulic pump which supplies a working fluid to the hydraulic motor, and wherein said processor means is connected to said hydraulic pump for controlling the rate of fluid discharge from the hydraulic pump so as to regulate the speed of the screw shaft. ### Claim 8 (depends on 7) The pipe propelling machine according to claim 7, wherein said processor means includes means to compare the calculated pressure difference to a first control value and to adjust the discharge of working fluid from the hydraulic pump so as to cause an increase in the screw shaft speed if the calculated pressure difference is less than the first control value, and to compare the calculated pressure difference to a second control value and to adjust the discharge of working fluid from the hydraulic pump so as to cause a decrease in the screw shaft speed if the calculated pressure difference is greater than the second control value.