초록 ▼

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), where the device (15) is provided with a controlled inlet valve (16) which is connected to the air

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), where 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), where 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).

대표청구항 ▼

1. Device for adjusting operating pressure of an oil-injected compressor installation including a compressor element driven by a motor having an adjustable rotational speed, controlled by a control module, and including an air inlet and a compressed air outlet to which is connected an oil separator

1. Device for adjusting operating pressure of an oil-injected compressor installation including a compressor element driven by a motor having an adjustable rotational speed, controlled by a control module, and including an air inlet and a compressed air outlet to which is connected an oil separator connected to a compressed air pipe supplying compressed gas, said device comprising: a controlled inlet valve connected to the air inlet and a blow-off mechanism connected to a blow-off pipe which connects the oil separator to the inlet valve and is closeable by a blow-off valve,said inlet valve, blow-off valve and control module comprising electrically controllable components connected to an electronic control unit and arranged to adjust the operating pressure in the oil separator, said operating pressure being measured by an operating pressure sensor that is connected to the electronic control unit;wherein said inlet valve comprises a butterfly valve driven by a stepping motor having an accompanying electronic stepping motor card;wherein said electronic stepping motor card includes a micro step modus;wherein said control unit includes an operating pressure controller configured as a PID controller that generates an output signal representing a desired inlet flow of the compressor element to adjust the rotational speed of the motor, the inlet pressure at the air inlet and the exhaust flow;wherein the control unit also includes an inlet pressure controller configured as a PID controller that applies a PID algorithm using a deviation of the inlet pressure to generate a signal used to determine an angular velocity of the stepping motor, wherein a reinforcement used in the PID algorithm is adjusted to provide a proportional action for the PID controller responsive to a deviation of the inlet pressure, wherein the reinforcement is a function of the position of the inlet valve or of the relation between the absolute pressure following the inlet valve at the air inlet of the compressor element and the absolute pressure on the inlet side of the inlet valve. 2. Device according to claim 1, wherein the blow-off valve comprises a magnetic valve that is moveable between a closed and an open position. 3. Device according to claim 2, wherein the control unit includes a memory capable of storing the position of the magnetic valve. 4. Device according to claim 1, wherein the control unit includes a calculation block containing an algorithm which opens the blow-off valve or keeps it open when the desired inlet flow is smaller than the minimal inlet flow that is reached at a minimal rotational speed of the motor and a maximal pressure ratio over the compressor element; wherein the control unit is arranged to close the blow-off valve or keeps it closed when the desired inlet flow is larger than the sum of the minimal inlet flow and the exhaust flow; and wherein the control unit is arranged so that the position of the blow-off valve does not change when the minimal inlet flow is smaller than the desired inlet flow, which in turn is smaller than the sum of the minimal inlet flow and the exhaust flow. 5. Device according to claim 4, wherein the control unit, between the operating pressure controller and the calculation block, includes a low-pass filter. 6. Device according to claim 1, wherein the control unit includes a selection block containing an algorithm enabling direct adjustment of the operating pressure in a first selection position, and adjustment of the operating pressure in a second selection position, wherein the operating pressure is automatically maximized to an operating pressure value between the nominal operating pressure and the design pressure of the compressor installation, so that the peak value of the operating pressure, in the event of a transition from a loaded to an unloaded compressor installation, always is maintained below the design pressure of the compressor installation. 7. Device according to claim 1, including a control panel configured to enable adjustment of the desired operating pressure in the control unit. 8. Device according to claim 1, including a remote control arranged to adjust the operating pressure in the control unit. 9. Device according to claim 1, wherein the operating pressure controller includes an algorithm arranged to adjust the PID-factors of the operating pressure controller to ambient pressure. 10. Device according to claim 1, wherein the control unit includes a STARTUP modus according to which the inlet valve is entirely closed, the blow-off valve is opened and the motor is started only then and wherein, as soon as the motor has reached its full speed, the control unit automatically switches from STARTUP modus to a NOLOAD modus, so that the operating pressure is adjusted to a value which is lower than the opening pressure of the minimum pressure valve by the control unit. 11. Device according to claim 1, including proximity switches on the inlet valve which are arranged to detect when a valve body in said inlet valve approaches end positions and transmit information regarding such end positions to the control unit. 12. A method for adjusting operating pressure of an oil-injected compressor installation comprising a compressor element driven by a motor having an adjustable rotational speed, a control module that controls the compressor element, an air inlet, a compressed air outlet connected to an oil separator which is connected to a compressed air pipe supplying compressed gas, and a controlled inlet valve connected to the air inlet and a blow-off mechanism connected to a blow-off pipe which connects the oil separator to the inlet valve and is closeable by a blow-off valve, said method comprising the steps: measuring an operating pressure using an operating pressure sensor connected to an electronic control unit;controlling the operating pressure in the oil separator by adjusting the inlet valve, blow-off valve, and control module using the electronic control unit, wherein said electronic control unit comprises at least an operating pressure controller and an inlet pressure controller;regulating the rotational speed of the motor, the inlet pressure at the air inlet and the exhaust flow using the operating pressure controller, said operating pressure controller generating an output signal representing a desired inlet flow of the compressor element, wherein the operating pressure controller is configured as a PID controller;applying a PID algorithm using the inlet pressure controller to a deviation of the inlet pressure to generate a signal used to determine an angular velocity of a stepping motor, wherein said inlet pressure controller is configured as a PID controller; andwherein the signal is determined by adjusting a reinforcement of the PID algorithm to provide a proportional action for the pressure controller, wherein the reinforcement is a function of the position of the inlet valve or of the relation between the absolute pressure following the inlet valve at the air inlet of the compressor element and the absolute pressure on the inlet side of the inlet valve, andwherein said inlet valve is a butterfly valve driven by the stepping motor having an accompanying electronic stepping motor card including a micro step modus.