VALVE CONTROL

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Non-Provisional Patent Application of U.S. Provisional Patent Application No. 62/587,923 entitled“Methods and Systems for Air Compressor with Electric Inlet Valve Control” filed November 17, 2017, which is herein incorporated by reference in its entirety.

BACKGROUND

[0002] Conventionally, engine-driven power systems are configured to power multiple components, such as generators, air compressors, welders, to name but a few. Some air compressors employ pneumatic valves to regulate intake and/or outflows of air. However, pneumatic valves require sensitive equipment and frequent maintenance to ensure proper operation. Thus, systems and methods that improve upon the shortcomings of pneumatic valves used in air compressors is desirable.

SUMMARY

[0003] Systems and methods are disclosed for an electric inlet valve control for an air compressor, powered and controlled by electrical devices, substantially as illustrated by and described in connection with at least one of the figures. In particular, a system to provide electrical control of an electric inlet valve for a rotary screw compressor based on one or more control signals is disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a functional diagram of an example power system, in accordance with aspects of this disclosure.

[0005] FIG. 2 illustrates an example control for an air compressor, in accordance with the present disclosure.

[0006] FIG. 3 is a diagram of an example air compressor with an exploded view of an electrically controlled inlet valve, in accordance with aspects of this disclosure.

[0007] FIG. 4 is a diagram of another example air compressor with an exploded view of an electrically controlled inlet valve, in accordance with aspects of this disclosure.

[0008] FIG. 5 illustrates an example method of operating a power system, in accordance with aspects of this disclosure.

[0009] The figures are not necessarily to scale. Where appropriate, similar or identical reference numbers are used to refer to similar or identical components.

DETAILED DESCRIPTION

[0010] The present disclosure provides an electrically powered and controlled inlet valve of a rotary screw compressor. In examples, an electric current powering a stepper motor (or, in some examples, a linear solenoid or other electric powered motion device) is used to open and/or close an air passage completely or partially to control outlet pressure and/or intake airflow of a rotary screws compressor.

[0011] The electrically powered and controlled inlet valve (i.e. electric inlet valve) works by applying an electric voltage and/or current to a motor and/or solenoid to adjust a mechanical valve. The change in position of the mechanical valve on the inlet side of the compressor pump restricts inlet airflow to the pump. The inlet airflow restriction produces an outlet flow/pressure reduction of the fixed displacement rotary screw pump. Thus, the output of the compressor is controlled by restricting the inlet airflow. The electric power to command adjustment of the electric inlet valve can be modulated and/or controlled to move the valve from a closed position to an open position, throttled in between, and vice versa.

[0012] Conventional air compressor systems employ pneumatic inlet valves to throttle air into the compressor (e.g., a rotary screw air compressor). The pneumatic valve uses air pressure from the compressor pump to close the valve. The pneumatic valve can be controlled in a variety of ways. However, even with an alternative control, the valve is still pneumatically implemented, such that air pressure is used to position the valve.

[0013] Advantages of employing an electrically powered and controlled inlet valve include obviating the need for air circuits to operate the pneumatic valve, which can therefore be removed. Additional control and ease of setting pressure and/or flow values of the compressor is also provided.

[0014] Further, pneumatic control circuits contain water, which tends to condense out of the air at pressure when the air in the control lines cools. In many situations, such as in mobile applications, the ambient temperature in which the compressor is operating is often below freezing. As the compressor cannot operate when water in the control lines freezes, complex and expensive heaters are often employed. The heaters are used to pre-heat the control lines and components to maintain a temperature above freezing, to keep the water in a liquid form and thereby to facilitate free flow through the control system. Employing an electric inlet valve as disclosed herein removes the pneumatic air control system, including pneumatic tubes, hoses, regulating valves, passageways, etc., and therefore removes the issues that stem from water freezing in pneumatic controls during cold weather operations.

[0015] Conventionally, engine driven generators and air compressors systems are either driven at all times by a direct, continuous connection with the engine, or intermittently via a clutch or other variable and/or disconnecting member. Air compressors that turn continuously may be configured to stop producing air when pressurized output is not needed. Cessation of output from such air compressors can be achieved in a variety of ways, such as by closing the air compressor inlet, or diverting the unused air to be exhausted to the atmosphere.

[0016] In the example of a fixed throttle air compressor driven by the engine, this idle speed varies depending on the engine temperature and compressor load, which are both variables dependent on ambient temperature, system temperature, operating conditions of the components, etc. Such conventional systems typically do not operate with other airflow controls, since the air compressor is either on or off.

[0017] Variable output (e.g., flow and/or pressure) air compressors are desirable, however, due to the lower operating costs associated with saved fuel and less demand for maintenance. Compressors that are configured to be disconnected from the engine have the advantage of turning on and off as needed. This is of particular value for engines configured to power multiple devices, such as an air compressor and/or a generator. For example, if only output from the generator is needed, the compressor can be turned off. If an output is needed (e.g. pressurized air), the clutch can engage the compressor and activate airflow to provide pressurized air as needed.

[0018] For a reciprocating type compressor, the clutch cycles on and off to increase air pressure within an air tank, or housing, as need. For a rotary screw compressor, the clutch can be cycled by a pressure switch in the air tank. If no tank is being used, a control scheme can determine the timing and operation of the throttle at the air inlet to meet output demand. For instance, the inlet throttle control can be a proportional, electrically controlled inlet valve that adjusts the position of the valve to change inlet pressure to meet a target output pressure level. The electric inlet valve can be configured to partially open to control flow levels, as well as opening fully to allow maximum flow at the inlet. The inlet throttle control can be electronically controlled and electrically powered (e.g. via an electric motor), such that the electric inlet valve is adjusted in response to an input from a controller. The input from the controller can be modulated electrical power and/or a control signal. Control signals can be derived from inputs to the controller, such as when a pressure switch, sensor, or other input (e.g., from an operator) identifies a predetermined pressure level, and adjusts the valve to allow a different pressure level in the compressor tank.

[0019] Conventional (i.e. pneumatic) systems are configured to maintain the compressor at full pressure, yet providing no output flow, when no output air is needed. Operating in this mode, however, consumes a high amount of power (i.e., requires significant fuel consumption) as, even though the pump is not pumping air for an output, the pump is spinning against a high differential pressure. The differential pressure is the case pressure (e.g., built up pressure within the housing) of the compressor which is at the output set pressure (e.g., about 150 pounds per square inch (psi)), less the inlet to the pump which is at a near vacuum (e.g., about -14 psi) when the inlet valve is closed.

[0020] The systems and methods described herein provide an improvement to conventional pneumatic inlet valves by replacing the pneumatically controlled inlet valves with an electrically powered and controlled inlet valve. [0021] The electric inlet valve can be controlled by a controller (e.g., a computer, microprocessor, logic instructions, etc.). The controller is configured to receive information regarding pressure, temperature, airflow, and other feedback information from the compressor, as well as information from other sources, such as engine inputs (e.g., speed, power, etc.), operator inputs, etc. The controller analyzes and employs the information to determine an output signal to control the electric inlet valve (e.g., a position of the inlet valve, amount of airflow required, etc.). Thus, the controller controls the electric inlet valve to a position as determined (e.g., based on the information and the original position of the valve) via one or more control schemes, such as an open or closed feedback loop.

[0022] In disclosed examples, the electric inlet valve can be controlled by analog circuits and/or a variety of switching devices, such as pressure or other mechanical switches. For example, a variety of applications may not employ digital controls and/or computational logic. However, by employing an analog circuit and/or switching device that is triggered in response to one or more conditions (e.g., exceeding a threshold pressure, power, voltage, and/or current value), will similarly benefit from the electric inlet valve disclosed herein.

[0023] In some examples, based on a determination that the compressor is not in use, the controller controls the electric inlet valve to a closed position to stop airflow into the compressor. Further, the compressor can reduce internal case pressure via a bleed down valve, and/or as an integrated function of the electric inlet valve to reduce the standby load of the compressor. Additionally or alternatively, the compressor can be declutched and the engine can be controlled to idle in response to a determination that the compressor is not in use.

[0024] Electric control of the compressor inlet valve allows control of the valve without the need for pneumatic control, such as when no air pressure is present. The electric inlet valve can therefore close before starting of the compressor to produce“softer” (i.e. lower power) starts, and to reduce wear on the compressor clutch. The compressor can operate at relatively low pressures, below what is needed when using a pneumatic valve control. The controller can maintain the electric inlet valve in a closed position even after the compressor is shut off and pressure is bled down, including when pressure levels in the compressor fall below a level required for pneumatic control. This prevents oil mist and/or fumes from evacuating the compressor case as the compressor blows down and/or cools down.

[0025] Electric control of the compressor inlet valve further allows the operator to select pressure via the controller (e.g., via a user interface, control panel, remote system, etc.). The controller controls the electric inlet valve to regulate airflow into the pump, which produces the selected/desired pressure and/or output flow at the outlet of the compressor. Use of an electric control allows an operator to make a selection for the controller by a system remote from the compressor (e.g., via a wired and/or wireless communications protocol).

[0026] Electric inlet valve can be controlled to regulate flow and or pressure output of the compressor to a higher or lower level to match a needed output for a selected process, such as a welding and/or a cutting process. For example, the pressure output can be reduced and maintained at a low pressure for plasma cutting or carbon arc cutting to reduce power consumption and match the air delivery needs of those processes. As disclosed herein, the controller can identify an operator process selection and dynamically adjust the compressor output accordingly. The electric control eliminates the need of an operator to select the process and then set the air pressure level, as the electronic control sets the compressor to match the selected process. The result is similar to an“Autoset” feature (e.g., as can be found in MIG machines) such that a single input into the controller determines the settings of multiple machine parameters (e.g., on the power supply, welder, air compressor, load, etc.). Thus, the resulting process is simpler, requires fewer inputs from the operator, and avoids operator error in equipment setup.

[0027] To improve upon conventional designs, the disclosed electric inlet valve allows the controller to reduce power consumption and/or output of the compressor. For example, when the controller determines the engine and/or the motor powering the compressor has a larger load than the current operating capacity (e.g., based information from one or more sensors, associated systems, a user input, etc.), the electric inlet valve can be adjusted to regulate the airflow in the compressor. Such a condition may result from overloading, or to reduce overheating in high ambient temperatures. This configuration results in a compact, cost effective, and reliable system, with the compressor to be driven by the engine.

[0028] The system can be housed in an enclosure, the engine being a source of mechanical power, with the compressor utilizing that power to provide output in the form of compressed air. The mechanical power of the engine is transferred to the air compressor via a clutch, belt, idler pulley, compressor pulley, etc., which is directly connected to the engine crankshaft. In some examples, the engine is directly coupled to an electric generator to generate electrical power.

[0029] The electric inlet valve can be located within the enclosure and/or integrated with the air compressor, such as in an inlet air path. For instance, the electric inlet valve can be mounted directly to an inlet of the screw housing, or it can be mounted separate from the screw housing, such as coupled to the system via a hose, a pipe, etc.

[0030] In disclosed examples, a variety of mechanical configurations of the electric inlet valve are possible. For instance, the electrically powered operating mechanism could be a poppet valve, a rotary valve, a spool valve, a pressure balanced valve, etc. Further, to facilitate the activation and/or deactivation of the electric inlet valve, one or more of the mechanical vales can include a spring, a diaphragm, an orifice, a piston, among other configurations.

[0031] In some examples, the air compressor is a rotary screw type compressor driven by the engine. A rotary screw compressor is a type of gas compressor that uses a rotary type positive displacement mechanism. They are used to replace piston compressors where large volumes of high-pressure air are needed, such as for construction or industrial applications. The gas compression process of a rotary screw is a continuous sweeping motion, so the pressure build up is generally smooth relative to a piston compressor. Additionally, rotary screw compressors are relatively compact and operate smoothly with limited vibration. Some rotary screw compressors are characterized as oil-injected, where lubricating oil aids in sealing and cooling functions.

[0032] In disclosed examples, an air compressor control system includes an electric inlet valve configured to regulate airflow of an air compressor based on a position of the electric inlet valve, and a controller configured to adjust a position of the electric inlet valve via an electrical control signal. In some examples, a sensor is configured to measure one or more characteristics of the air compressor. In examples, the sensor is a pressure sensor having an adjustable pressure range.

[0033] In examples, a user interface configured to select a pressure level to the controller. In some examples, the controller is configured to receive a selected pressure level for the air compressor from the user interface, receive a signal corresponding to a measured pressure level of the air compressor from the sensor, compare the selected pressure level to the measured pressure level, and calculate a pressure difference based on the comparison. In examples, an electrically controlled and powered motor configured to adjust a position of the electric inlet valve, wherein the controller is configured to determine a position of the electric inlet valve; calculate a change in position of the electric inlet valve based on the pressure difference; and control the motor to adjust the position of the electric inlet valve based on the calculated change in position.

[0034] In disclosed examples, an air compressor control system includes a user interface configured to receive a command from an operator; a sensor configured to measure one or more characteristics of the system; an electric inlet valve integrated within an air compressor and configured to regulate airflow of the air compressor based on a position of the electric inlet valve; and a controller configured to adjust a position of the electric inlet valve via an electrical control signal in response to a command from the user interface or a measurement from the sensor.

[0035] In some examples, the controller is configured to automatically determine a desired pressure level in the air compressor based on the command or the measurement. In examples, the command corresponds to a gouging or plasma cutting operation. In some examples, the controller is configured to: receive a selected gouging or plasma cutting operation from the user interface; determine a desired air pressure for the air compressor based on the selected operation; compare the desired air pressure level to a measured air pressure level; and calculate a pressure difference based on the comparison.

[0036] In examples, a motor configured to adjust a position of the electric inlet valve, wherein the controller is configured to: determine a position of the electric inlet valve; calculate a change in position of the electric inlet valve based on the pressure difference; and control the motor to adjust the position of the electric inlet valve based on the calculated change in position. In some examples, the sensor is a pressure sensor having an adjustable pressure range. [0037] In disclosed examples, a method of controlling an air compressor includes measuring, by a sensor, a pressure at an inlet or an outlet of the air compressor; and adjusting a position of an electric inlet valve via an electrically powered mechanism to regulate airflow of the air compressor in response to an electrical control signal.

[0038] In some examples, the method further includes receiving, at the controller, a pressure level selection from a user interface. In some examples, the method further includes receiving a signal corresponding to a measured pressure level of the air compressor from the sensor. In some examples, the method further includes comparing the selected pressure level to the measured pressure level; and calculating a pressure difference based on the comparison.

[0039] In some examples, the method further includes determining, by the controller, a position of the electric inlet valve; and calculating, by the controller, a change in position of the electric inlet valve based on the pressure difference. In some examples, the electrically powered mechanism is a motor, the method further includes controlling the motor to adjust the position of the electric inlet valve based the calculated change in position.

[0040] In some examples, the sensor is a pressure sensor having an adjustable pressure range. In some examples, the method further includes shutting off the air compressor; and controlling the motor to maintain the electric inlet valve in a closed position to prevent oil mist and/or fumes from evacuating the compressor case as the air compressor cools down.

[0041] In disclosed examples, an engine driven power system includes a power supply; an air compressor comprising an electric inlet valve; and a controller configured to receive an input corresponding to one or more parameters associated with the power supply or the air compressor, and generate one or more electrical control signals to regulate an output of the power supply and to regulate airflow of the air compressor in response to the input. [0042] In some examples, the input corresponds to a single input that provides a plurality of parameter settings for the power supply and the air compressor. In examples, the input corresponds to a gouging or plasma cutting operation. In some examples, a sensor to measure a pressure at an inlet or an outlet of the air compressor.

[0043] In some examples, the controller is configured to receive a signal corresponding to a measured pressure level of the air compressor from the sensor; compare the selected pressure level to the measured pressure level; and calculate a pressure difference based on the comparison. In examples, the controller is further configured to determine a position of the electric inlet valve; and calculate a change in position of the electric inlet valve based on the pressure difference.

[0044] In examples, the electrically powered mechanism is a motor, the controller further configured to control the motor to adjust the position of the electric inlet valve based the calculated change in position. In some examples, the controller is configured to command the air compressor to shut off; and to control the motor to maintain the electric inlet valve in a closed position to prevent oil mist and/or fumes from evacuating the compressor case as the air compressor cools down.

[0045] Advantages of the present disclosed methods and apparatuses include the elimination of pneumatic control lines, which are prone to freezing when exposed to cold temperatures. The system allows operators to set pressure from an electronic user interface, which can be a remote pressure adjustment control. Further, expensive pneumatic control components and heater systems are reduced and/or eliminated by implementation of the electronic control systems.

[0046] The use of a controller and electronic components allows for receipt and analysis of multiple feedback parameters (e.g., pressure at the electric inlet valve, outlet valve, within the compressor case; engine speed; power output characteristics such as voltage, current; system temperature; etc.) and operates the air compressor in different modes more easily than a conventional, mechanical control (e.g., standby mode, low power mode, startup mode, idle mode, etc.).

[0047] As used herein, the term“welding-type power” refers to power suitable for welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding). As used herein, the term“welding-type power supply” refers to any device capable of, when power is applied thereto, supplying welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding) power, including but not limited to inverters, converters, resonant power supplies, quasi-resonant power supplies, and the like, as well as control circuitry and other ancillary circuitry associated therewith.

[0048] As used herein, a“circuit” includes any analog and/or digital components, power and/or control elements, such as a microprocessor, digital signal processor (DSP), software, and the like, discrete and/or integrated components, or portions and/or combinations thereof.

[0049] As used herein, the terms“first” and“second” may be used to enumerate different components or elements of the same type, and do not necessarily imply any particular order. For example, while in some examples a first compartment is located prior to a second compartment in an airflow path, the terms“first compartment” and“second compartment” do not imply any specific order in which airflows through the compartments.

[0050] FIG. 1 is a functional diagram of an example power system 100. The system 100 is an engine-driven power system, which includes an engine 104 that drives an air compressor 102 (e.g., a rotary screw type air compressor). The air compressor 102 is driven by the engine 104 via a clutch 106. The air compressor 102 can include one or more sensors 108 to sense and/or measure a pressure at one or more locations within the system. Sensors 108 can also be used to directly and/or indirectly measure variables such as airflow, changes in temperature, forces acting on housings, among others. The sensors 108 can be any type of sensor configured to measure a pressure, including analog and digital sensors, force collector type sensors such as piezo-resistive strain gauge, piezoelectric, optical fiber based sensors, potentiometric thermal sensors, transducers, pressure indicators, piezometers, manometers, to name but a few.

[0051] In the example of FIG. 1, the sensor 108 measures pressure(s) within a housing/tank of the air compressor 102, at an outlet, an inlet, and/or another location of the air compressor 102. A motor and/or solenoid 110 is configured to control an electrically controlled compressor inlet valve 111 and to adjust pressure in the compressor case from the electric inlet valve 111. In examples, a controller 114 is configured to monitor and/or control one or more conditions of the system 100. For instance, the controller 114 receives information from the sensor 108, as well as other operating parameters (e.g., temperature, rotation speed of one or both of the compressor 102 and engine 104, etc.) of the system 100.

[0052] In some examples, an electrical generator 120 is connected to the engine 104 to provide one or more types of electrical power suitable for specific and/or general purpose uses, such as welding-type power, 110 VAC and/or 220 VAC power, battery charging power, and/or any other type of electrical power. The input and output characteristics of the generator 120 (e.g., voltage, current, power, rotational speed, etc.) can be provided to the controller 114 to determine if and how much adjustment to the inlet valve 11 is needed. Furthermore, the example system 100 may include other components not specifically discussed herein. [0053] In some examples, the system 100 employs a controller 114 for controlling an output of the air compressor 102. For instance, the controller 114 can engage the clutch 106 to operate at variable speeds in response to the speed of the engine 104, operate one or more valves to release pressure from the air compressor 102, as well as controlling the engine 114 to idle, such as when the compressor 102 is not in use. Additionally or alternatively, a user interface 118 can be employed to allow a system operator to adjust one or more parameters associated with the system 100. For example, one or more predetermined pressure levels and/or ranges can be adjusted via the user interface 114 to accommodate a particular operation or need. The user interface 118 can be integrated with and/or located remotely from the air compressor 102 and/or the controller 114.

[0054] In other examples, an operation of the welding system 100 can be selected (e.g., via user interface 118) or automatically determined by the controller 114 based on an analysis of received data (e.g., via sensor 108). The electrical control system enables the use of an “AutoSet” feature, such that the engine driven unit can coordinate with the air compressor output pressure. Thus, a change in process and/or output requirements can set or command an adjustment in the air compressor in response to the change of process and/or selection. In other words, a single input from the operator produces setup parameters for the welding system and the compressor. The result is a more responsive, faster acting air compressor, which provides more precise control of the compressor outlet than conventional systems are capable of.

[0055] The controller 114 is able to receive and analyze multiple parameters associated with the air compressor 102 or they system 100 (e.g., pressure at the electric inlet valve 111, outlet valve 116, within the compressor case; speed of the engine 104; power output characteristics such as voltage, current; system temperature; etc.) and operates the air compressor 102 in different modes more easily than a conventional, mechanical control (e.g., standby mode, low power mode, startup mode, idle mode, variable pressure, etc.). Thus, a more informed analysis is conducted in determining the proper valve adjustment.

[0056] In response to a process selection, the controller 114 can dynamically control a position of the electric inlet valve 111 to adjust the amount of airflow through the compressor inlet. In this manner, the controller 114 automatically sets the pressure (e.g., via the“Autoset” feature) to provide airflow as needed for a particular operation (e.g., cutting, gouging, welding, etc.).

[0057] Additionally or alternatively, the controller 114 can command the air compressor 102 or the engine 104 to change mode (e.g., standby, idle, full operational speed, etc.) based on the received and analyzed data. For instance, if the system 100 is set for a plasma cutting operation, the air compressor 102 may require an increase in air pressure. Thus, the controller 114 will adjust the electric inlet valve to increase the air pressure.

[0058] Conversely, if the system 100 is powered down, the controller 114 can institute one or more procedures to shut down one or more components of the system. For example, the controller 114 can maintain the electric inlet valve 111 in a closed position even after the air compressor 102 is shut off and pressure is bleed down. This prevents oil mist and/or fumes from evacuating the compressor case as the air compressor 102 cools down and/or blows down.

[0059] In some examples, the sensor 108 is one or more transducers 112 configured to measure a pressure level one or more locations of the air compressor (e.g., at an outlet, at a housing, at the inlet, etc.). The transducer H2can transmit the information to the controller H4via a signal indicating the pressure level to the controller 114 via one or more circuits. The controller 114 can be configured to control the electric inlet valve 111, to activate in response to a change in the measured or selected pressure level.

[0060] Further, the controller 114 can control the clutch 106 to disengage in response to the second pressure level being below a second, low-pressure level. In this example, the sensor 108 is able to sense the pressure at multiple locations, such as by alternating measurements, and the controller 114 is capable of analyzing the signals from the sensor 108 to determine the appropriate control.

[0061] Additionally or alternatively, the system 100 includes a timer, such as a countdown timer or other suitable timing device (e.g., incorporated with a microprocessor, etc.), configured to activate in response to a high-pressure level being sensed by the sensor 108. Simultaneously or in response to the closure of the electric inlet valve 111, the timer counts down a predetermined duration (e.g., between about 30 seconds and 2 minutes), which, upon expiry, can inform the controller 114 to disengage the clutch 106. Before disengaging the clutch 106, the controller 114 determines if the pressure level has reset (e.g., the sensor 108 no longer senses the high-pressure level). Thus, the timer is reset each time the sensor 108 indicates the high-pressure condition is no longer present.

[0062] In examples, when a pre-determined pressure level is reached (e.g., 150 psi), the controller 114 activates the electric inlet valve 111. The electric inlet valve 111 closes to stop the compressor 102 from pumping air.

[0063] In some examples, the controller 114 is configured to sense or receive information indicating that the air output has not been used, and proceeds to idle the engine 104 based on the information. The controller 114 responds to the low-pressure in the compressor case. Once the low-pressure level is met in the compressor case, the clutch 106 to disengages in response. [0064] The clutch 106 disengages and an electrical signal from the controller 114 can be used to direct the engine 104 to enter into an idle mode. In examples where no load is on the engine 104, the engine 104 can idle with a fixed engine throttle position idle system at a consistent and predictable speed. With the clutch 106 disengaged, the compressor 102 enters into a stand-by mode. For instance, stand-by mode corresponds to the outlet pressure being maintained via the outlet valve 116 while the compressor 102 is at low or no pressure and disconnected from the engine 104. The compressor 102 is still on and restarts when air pressure at the outlet is reduced to a predetermined pressure level.

[0065] When air is used (e.g., to operate an air drive tool), the compressor 102 responds by starting to pump air again. In response, the compressor clutch 106 engages and the electrically controlled compressor inlet valve 111 opens, allowing air into the now turning pump within the compressor 102. Additionally or alternatively, the controller 114 is designed to re-start the compressor 102 from a stand-by mode, which is an improvement over conventional compressor control schemes.

[0066] FIG. 2 illustrates an example control 200 for an air compressor, in accordance with the present disclosure. As shown in FIG. 2, an inlet filter 202 is connected to an electric inlet valve 211 to allow air to flow into the compressor. A blowdown valve 206 is connected to a blowdown orifice 208. A pressure transducer 214 is configured to measure a pressure level of the compressor. A minimum pressure control valve 216 incorporates a check valve to maintain pressure downstream during blowdown of the compressor case. The pressure transducer 214 is placed after the minimum pressure/check valve 216 to measure the output pressure of the compressor. The inlet valve 211 is configured to open, close, or modulate air flow in response to a change from the pressure transducer 214. For example, a controller (e.g., the controller 114) can receive and analyze signals from one or more components (e.g., the pressure transducer 214) and generate a command signal to control operation of the electric inlet valve 202, for instance.

[0067] The blowdown valve 206 is configured to open in response to the pressure transducer 214 sensing a pressure above a predetermined threshold level, a duration of no output (e.g., a time delay), a low pressure switch 412, or another means of determining the air compressor is not in use. Once activated/opened, the blowdown valve 206 releases air from the compressor case. For instance, once pressure transducer 214 senses a predetermined pressure level, the electric inlet valve 211 is closed and the blowdown valve 206 is opened to provide a timed pressure reduction of the compressor case until the pressure transducer 214 no longer senses the pressure level above the predetermined threshold level.

[0068] A second, low-pressure switch 412 may be configured to sense a second, low- pressure level in the compressor case, which can in response control a clutch (e.g. clutch 106) to disengage from an engine (e.g., engine 104). In particular, as the compressor case bleeds down and the pressure reduces to a predetermined level (e.g., 30 psi), the low-pressure switch 412 deactivates/opens which disengages the compressor clutch. The clutch disengages, which can also indicate that the engine is to enter into an idle mode.

[0069] If the pressure at the pressure transducer 214 senses a pressure below the predetermined threshold level, the controller closes the blowdown valve 206 and opens the electric inlet valve 211. The clutch can also be engaged, such that the engine is capable of turning the air compressor to increase pressure within the housing.

[0070] Additionally or alternatively, the control 200 can include a pressure relief valve 418 as a safety outlet, pressure gauge 220, and an over pressure switch 210. For example, when a pressure exceeds a predetermined level, an over pressure switch 210 activates which disengages the compressor clutch. A case temperature sensor 222 can also provide information regarding a temperature in the air compressor. In some examples, the control circuit 200 may implement and/or be integrated into the controller 114 of FIG. 1. In some examples, the control circuit 200 is a wholly separate controller configured to respond to changes in pressure and control the system components. The example circuit 200 responds to changes in the pressure level at the compressor 102 and controls the electric inlet valve 111 accordingly.

[0071] FIG. 3 is a diagram of an example air compressor 302 with an exploded view of an electrically powered and controlled inlet valve 311, in accordance with aspects of this disclosure. In the example of FIG. 3, the electrically controlled inlet valve 311 includes one or more components to regulate flow of air into the air compressor 302. The components can include a conical spring 1, O-rings 2, 3, and a valve disk with O-ring and rod 4. Additionally, a motor 310 is included to adjust a position of the electrically controlled inlet valve 311, as described with respect to FIGS. 1 and 2. Thus, motor 310 (e.g., such as motor and/or solenoid 110) can receive commands from a controller (e.g., controller 114) to adjust the position of the electrically controlled inlet valve 311 in order to provide the desired pressure level.

[0072] FIG. 4 is a diagram of another example air compressor 402 with an exploded view of an electrically powered and controlled inlet valve 411, in accordance with aspects of this disclosure. In the example of FIG. 4, the electrically controlled inlet valve 411 includes one or more components to regulate flow of air into the air compressor 402. The components can include a conical spring 1, hex-nut 2, conical spring 3, piston 4, V-ring 5, O-rings 6, 7, lock washer 8, plate set 9, O-ring 10, and rod 11. Additionally, a motor 410 (e.g., such as motor and/or solenoid 110) is included to adjust a position of the electrically controlled inlet valve 311, as described with respect to FIGS. 1 and 2. Thus, motor 410 can receive commands from a controller (e.g., controller 114) to adjust the position of the electrically controlled inlet valve 411 in order to provide the desired pressure level.

[0073] FIG. 5 is a flowchart illustrating example method 500 of controlling an engine driven air compressor, as described with respect to FIGS. 1 and 2. In block 502, a sensor (e.g., the sensor 108) measures a pressure at an inlet or an outlet (e.g., the outlet 116) of the air compressor (e.g., the air compressor 102). In block 504, a controller (e.g., controller 114) receives a signal corresponding to a measured pressure level of the air compressor from the sensor.

[0074] At block 506, the controller receives a pressure level selection from a user interface (e.g., user interface 118). At block 508, the controller compares the selected pressure level to the measured pressure level. At block 510, the controller calculates a pressure difference based on the comparison.

[0075] At block 512, the controller determines a position of an electric inlet valve (e.g., electric inlet valve 111). At block 514, the controller calculates a change in position of the electric inlet valve based on the pressure difference. At block 516, the controller generates an electrical control signal based on the calculated change in position. At block 518, the controller adjusts a position of an electric inlet valve via a motor (e.g., motor 110) to regulate airflow of the air compressor based on the electrical control signal. The process then returns to block 502 to continue monitoring and measuring a pressure of the air compressor.

[0076] Additionally or alternatively, method 500 of FIG. 5 may be implemented by the controller 114 of FIG. 1 by executing machine -readable instructions, such as stored on a non- transitory machine-readable storage device. In such an examples, the controller 114 can receive electronic signals from the system sensors (e.g., sensor 108, transducer 112, or other system sensors) and control the system components (e.g., electric inlet valve 111) based on a series of algorithms and/or calculations consistent with the examples provided herein.

[0077] As utilized herein,“and/or” means any one or more of the items in the list joined by “and/or”. As an example,“x and/or y” means any element of the three-element set {(x), (y), (x, y)}. In other words,“x and/or y” means“one or both of x and y”. As another example,“x, y, and/or z” means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words,“x, y and/or z” means“one or more of x, y and z”. As utilized herein, the term “exemplary” means serving as a non-limiting example, instance, or illustration. As utilized herein, the terms“e.g.,” and“for example” set off lists of one or more non-limiting examples, instances, or illustrations.

[0078] While the present method and/or system has been described with reference to certain implementations, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present method and/or system. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. For example, systems, blocks, and/or other components of disclosed examples may be combined, divided, re arranged, and/or otherwise modified. Therefore, the present method and/or system are not limited to the particular implementations disclosed. Instead, the present method and/or system will include all implementations falling within the scope of the appended claims, both literally and under the doctrine of equivalents.