# US 2010/0166571 A1 · Device for regulating the operating pressure of an oil-injected compressor installation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0166571 A1 - Document ID: US20100166571A1 - Status: Published application - Kind: A1 - Application number: 12/303,940 - Filed: 2007-03-21 - Published: 2010-07-01 - Earliest claimed: 2006-06-09 - Assignees: Atlas Copco Airpower, Naamloze Vennootschap - Inventors: Peter Van Den Wyngaert; Ivo Daniëls - Web page: https://patentgrep.com/patent/US20100166571A1 ## CPC - F04C 18/16: with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)} - F04B 49/065: {and making use of computers} - F04B 49/20: by changing the driving speed - F04B 49/225: {with throttling valves or valves varying the pump inlet opening or the outlet opening} - F04C 28/26: using bypass channels - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) ## Abstract Device for adjusting the operating pressure of an oil-injected compressor installation with a compressor element (2) driven by a motor (4) with an adjustable rotational speed and a control module (13), whereby the device (15) is provided with a controlled inlet valve (16) which is connected to the air inlet (5) and a blow-off mechanism (17) which can be closed by means of a blow-off valve (19), wherein the inlet valve (16), the blow-off valve (19) and the control module (13) are electrically controllable components which are connected to an electronic control unit (22) for adjusting the operating pressure (Pw), which is measured by an operating pressure sensor (23). ## Claims ### Claim at position 1 1-15. (canceled) ### Claim 16 Device for adjusting the operating pressure of an oil-injected compressor installation including a compressor element (2) driven by a motor (4) having an adjustable rotational speed, controlled by a control module (13), and including an air inlet (5) and a compressed air outlet (7) to which is connected an oil separator (10) connected to a compressed air pipe (11) supplying compressed gas, said device (15) comprising a controlled inlet valve (16) connected to the air inlet (5) and a blow-off mechanism (17) connected to a blow-off pipe (18) which connects the oil separator (10) to the inlet valve (16) and is closeable by a blow-off valve (19), said inlet valve (16), blow-off valve (19) and control module (13) comprising electrically controllable components and being connected to an electronic control unit (22) arranged to adjust the operating pressure (Pw) in the oil separator (10), said oil pressure being measured by an operating pressure sensor (23) that is connected to the electronic control unit (22); wherein said inlet valve (16) comprises a butterfly valve driven by a stepping motor (20) having an accompanying electronic stepping motor card (21); wherein said electronic stepping motor card (21) includes a micro step modus; wherein said control unit (22) includes an operating pressure controller (27) configured as a PID controller having an output signal representing a desired inlet flow (102) of the compressor element (2), on the basis of which the rotational speed of the motor, the inlet pressure (Pi) at the air inlet (5) and the exhaust flow (Qb) are adjusted; wherein the control unit (22) includes an inlet pressure controller (28) which is configured as a PID controller with a reinforcement (K), wherein the reinforcement (K) is a function of the position of the inlet valve (16) or of the relation between the absolute pressure following the inlet valve (16) at the air inlet (5) of the compressor element (2) and the absolute pressure on the inlet side of the inlet valve (16). ### Claim 17 (depends on 16) Device according to claim 16, wherein the blow-off valve (19) comprises a magnetic valve that is moveable between a closed and an open position. ### Claim 18 (depends on 16) Device according to claim 16, wherein the control unit (22) includes a memory capable of storing the position of the magnetic valve. ### Claim 19 (depends on 16) Device according to claim 16, wherein the control unit (22) includes a calculation block (38) containing an algorithm which opens the blow-off valve (19) or keeps it open when the desired inlet flow (102) is smaller than the minimal inlet flow (Qi,min) that is reached at a minimal rotational speed of the motor and a maximal pressure ratio over the compressor element (2); wherein the control unit (22) is arranged to close the blow-off valve (19) or keeps it closed when the desired inlet flow (102) is larger than the sum of the minimal inlet flow (Qi,min) and the exhaust flow (Qb); and wherein the control unit (22) is arranged so that the position of the blow-off valve (19) does not change when the minimal inlet flow (Qi,min) is smaller than the desired inlet flow (102), which in turn is smaller than the sum of the minimal inlet flow (Qi,min) and the exhaust flow (Qb). ### Claim 20 (depends on 19) Device according to claim 19, wherein the control unit (22), between the operating pressure controller (27) and the calculation block (38), includes a low-pass filter (40). ### Claim 21 (depends on 16) Device according to claim 16, wherein the control unit (22) includes a selection block (31) containing an algorithm enabling direct adjustment of the operating pressure (Pw) in a first selection position, and adjustment of the operating pressure in a second selection position, wherein the operating pressure (Pw) is automatically maximized to an operating pressure (Pw) value between the nominal operating pressure and the design pressure of the compressor installation (1), so that the peak value of the operating pressure (Pw), in the event of a transition from a loaded to an unloaded compressor installation (1), always is maintained below the design pressure of the compressor installation (1). ### Claim 22 (depends on 16) Device according to claim 16, including a control panel (26) configured to enable adjustment of the desired operating pressure in the control unit (22). ### Claim 23 (depends on 16) Device according to claim 16, including a remote control arranged to adjust the operating pressure in the control unit (22). ### Claim 24 (depends on 16) Device according to claim 16, wherein the operating pressure controller (27) includes an algorithm arranged to adjust the PID-factors of the operating pressure controller (27) to ambient pressure (Patm). ### Claim 25 (depends on 16) Device according to claim 16, wherein the control unit (22) includes a STARTUP modus according to which the inlet valve (16) is entirely closed, the blow-off valve (19) is opened and the motor (4) is started only then and wherein, as soon as the motor (4) has reached its full speed, the control unit (22) automatically switches from STARTUP modus to a NOLOAD modus, so that the operating pressure (Pw) is adjusted to a value which is lower than the opening pressure of the minimum pressure valve (12) by the control unit (22). ### Claim 26 (depends on 16) Device according to claim 16, including proximity switches (25) on the inlet valve (16) which are arranged to detect when a valve body in said inlet valve (16) approaches the end positions and transmit information regarding such end positions to the control unit (22).