Pneumatic inlet valve and bleed valve assembly

Abstract

A fluid compressor system includes a pneumatic inlet valve and a relief valve assembly that utilizes pneumatic pressure and vacuum available within the fluid compressor system to actuate the inlet valve and the relief valve. Actuation of the inlet valve and the relief valve is synchronized via a piston-cylinder actuator having an axially connected first piston and a second piston. The pneumatic inlet valve and relief valve assembly uses a first-stage vacuum pressure to actuate the first piston and the second piston, moving them from an idle state to an actuated state. In the idle state, the inlet valve is closed to stop the flow of working fluid into the fluid compressor system, while the relief valve is open to depressurize the fluid compressor system. In the actuated state, the inlet valve is open to allow working fluid to flow into a first main unit, while the relief valve is closed to allow pressure buildup in the fluid compressor system.

Description

Technical Field

[0001] This invention relates to a pneumatic inlet valve and a relief valve assembly. Background Technology

[0002] Compressors increase the pressure of compressible fluids (such as air, gas, etc.) by reducing their volume. Typically, compressors are staged, meaning the fluid is compressed several times in different stages to further increase its discharge pressure. As the fluid's pressure increases, its temperature also increases. In some compressors, the compressed fluid can be cooled between stages. Compressors are classified into positive displacement compressors and dynamic compressors. Attached Figure Description

[0003] Detailed description is provided with reference to the accompanying drawings. The same reference numerals are used to denote similar or identical parts in different embodiments of the specification and drawings.

[0004] Figure 1 This is an isometric front view of a pneumatic inlet valve and vent valve assembly according to an exemplary embodiment of the present invention.

[0005] Figure 2 yes Figure 1 The image shows an isometric rear view of a pneumatic inlet valve and vent valve assembly according to an exemplary embodiment of the present invention.

[0006] Figure 3 yes Figure 1 The figure shows a cross-sectional view of a pneumatic inlet valve and vent valve assembly according to an exemplary embodiment of the present invention, wherein the dual pistons are in an idle state.

[0007] Figure 4 yes Figure 1 The figure shows a cross-sectional view of a pneumatic inlet valve and vent valve assembly according to an exemplary embodiment of the present invention, wherein the double pistons are in an actuated state.

[0008] Figure 5 It is along Figure 3 The side sectional view of the pneumatic inlet valve and relief valve assembly, taken by line "5", shows the crankshaft connecting the piston shaft to the butterfly plate of the inlet valve.

[0009] Figure 6 This is a schematic diagram of a compression system including a pneumatic inlet valve and a relief valve assembly according to an exemplary embodiment of the present invention. Summary of the Invention

[0010] Although the subject matter has been described in specific language regarding structural features and / or process operations, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms of implementing the claims.

[0011] Overview

[0012] Fluid compressor systems increase the pressure of working fluids such as air or gas and are widely used in various industries, including construction, manufacturing, agriculture, and energy production. Positive displacement compressor systems, such as rotary screw compressors (but not limited to), confine a continuous volume of working fluid within a mechanically reduced enclosed space, compressing the fluid and increasing its pressure and temperature. Types of rotary screw compressors include contact-cooled rotary (CCR) compressors (also known as oil-filled rotary screw compressors) and oil-free rotary (OFR) compressors.

[0013] In fluid compressor systems, capacity control is used to regulate the volume of the compressed working fluid. The capacity of the fluid compressor system is the amount of working fluid the system will handle at a specific discharge pressure. In rotary screw compressors, different capacity control schemes are used, including start / stop, loading / unloading, modulation, variable capacity, and variable speed. Loading / unloading (with loading and unloading operations) and modulation capacity control schemes are controlled by synchronizing the operation of the inlet valve and the relief valve.

[0014] Compared to other types of valves, such as hydraulic valves and diaphragm valves, pneumatic valves offer several advantages. For example, pneumatic valves may be less prone to leaks, are more compact, and easier to maintain because pneumatic lines can be directly connected to the atmosphere, whereas the oil lines in hydraulic valves must be drained into the oil sump before any maintenance operations can be performed.

[0015] CCR compressors include a separator tank that stores compressed air that can be used as an actuation source for pneumatic valves, including inlet valves. A minimum pressure check valve (MPCV) maintains a minimum system pressure within the separator tank. Using this minimum system pressure facilitates pneumatic actuation of the inlet valves during cold starts or even when the system transitions from an unloaded to a loaded state. Therefore, most inlet valves in a CCR compressor are pneumatically operated.

[0016] OFR compressor systems typically do not have a separator tank with a minimum pressure check valve. Therefore, typically, an OFR compressor system does not have a minimum system pressure when actuating the pneumatic inlet valve from a cold start. In OFR compressor systems, the second-stage outlet is connected to a relief valve or unloading valve for unloading operations or starting the OFR compressor system with minimum back pressure. The operation of the inlet valve and relief valve is synchronized with the inlet valve in the closed position (normally closed) and the relief valve in the open position (normally open). No pressure buildup occurs in the OFR compressor system unless the relief valve is closed. Because the operation of both the inlet valve and relief valve is synchronized, finding a source of energy to close the relief valve is necessary to provide a fully pneumatic inlet valve for the OFR compressor system.

[0017] Therefore, the present invention relates to a fluid compressor system having a pneumatic inlet valve and a relief valve assembly, which utilizes a combination of pneumatic pressure and vacuum available in the fluid compressor system to actuate the inlet valve and the relief valve. The inlet valve and the relief valve are integrated together, wherein their actuation is synchronized with each other. Detailed Implementation

[0018] Overall reference Figures 1 to 6 A fluid compressor system 100 is shown. The fluid compressor system 100 includes a first main unit 136, a second main unit 138, and a pneumatic inlet valve and vent valve assembly 101. The fluid compressor system 100 may include a motor 140 driving the first main unit 136 and the second main unit 138. The first main unit 136 receives a compressible working fluid (e.g., air, gas, etc.) and compresses the working fluid during a first-stage compression process. This compression also increases the temperature of the working fluid.

[0019] In an exemplary embodiment, the fluid compressor system 100 includes a fluid filter 134 disposed upstream of the pneumatic inlet valve and vent valve assembly 101 and the first main unit 136. The fluid filter 134 can filter particles from the working fluid and prevent particulate matter from entering the fluid compressor system 100.

[0020] In an exemplary embodiment, the fluid compressor system 100 includes an intercooler 142 for cooling the working fluid delivered by the first host 136 and an interstage moisture separator 144 for separating moisture from the working fluid before it enters the second host 138. An interstage vent solenoid valve 146 may be coupled between the interstage moisture separator 144 and the second host 138 to release interstage pressure. In an exemplary embodiment (not shown), the fluid compressor system 100 may include an interstage venturi (also referred to as a first-stage venturi) that connects downstream of the first host 136 and upstream of the second host 138 to reduce pulsation within the compressed working fluid delivered by the first host 136.

[0021] The second host 138 receives the working fluid delivered by the interstage moisture separator 144 and further compresses the working fluid. In an exemplary embodiment, the fluid compressor system 100 also includes a discharge venturi 150 (also referred to as a second-stage venturi) to reduce pulsation of the compressed fluid discharged during the second-stage compression process occurring in the second host 138. After passing through the discharge venturi 150, the working fluid may exit the fluid compressor system 100 for delivery before flowing through the discharge check valve 152, aftercooler 154, and second-stage moisture separator 156.

[0022] exist Figures 1 to 5In the exemplary embodiment shown, the pneumatic inlet valve and relief valve assembly 101 includes an inlet valve 102, a relief valve 106, a piston-cylinder actuator 104, a first solenoid valve 110, and a second solenoid valve 112. The inlet valve 102 receives working fluid entering the fluid compressor system 100 and regulates its flow rate before it enters the first host unit 136. In the exemplary embodiment, the inlet valve 102 includes a butterfly plate 103. The butterfly plate 103 rotates between an open position and a closed position to allow or block working fluid from passing through the inlet valve 102, respectively.

[0023] The vent valve inlet 160 of the vent valve 106 is connected to the discharge vent tube 150 at the discharge port of the second host 138. The vent valve 106 is configured to release accumulated pressure within the fluid compressor system 100 through the vent valve outlet 162 when the fluid compressor system 100 is in unloading operation and the vent valve 106 is open. In an exemplary embodiment, the vent valve outlet 162 is connected to a vent silencer 148 to reduce noise and / or to a vent diffuser (not shown) to distribute the discharged hot, compressed working fluid.

[0024] like Figure 3 and Figure 4 As shown, a piston-cylinder actuator 104 is mechanically coupled to an inlet valve 102 and a relief valve 106. The piston-cylinder actuator 106 includes a first piston 132 housed within a first cylinder chamber 133 and a second piston 134 housed within a second cylinder chamber 135. The first cylinder chamber 133 has a first cylinder chamber end 133A and a second cylinder chamber end 133B. Similarly, the second cylinder chamber 135 has a first cylinder chamber end 135A and a second cylinder chamber end 135B. In an exemplary embodiment, the first piston 132 and the second piston 134 are axially connected by a piston shaft 122 having an axis 122A. The piston shaft 122 slides within the piston-cylinder actuator 104 in a linear motion along the axis 122A supported by a guide bearing 123.

[0025] The first cylinder chamber 133 defines a first chamber C1 between a first side of the first piston 132A and the first cylinder chamber end 133A, and a second chamber C2 between a second side of the first piston 132B and the second cylinder chamber end 133B. The second cylinder chamber 135 defines a third chamber C3 between a first side of the second piston 134A and the first cylinder chamber end 135A. The second cylinder chamber 135 also defines a fourth chamber C4 between a second side of the second piston 134B and the second cylinder chamber end 135B.

[0026] The first piston 132 and the second piston 134 include at least one piston seal 131 arranged around the outer periphery of each respective piston. The at least one piston seal 131 prevents air from escaping from the first cylinder chamber 133, between the first chamber C1 and the second chamber C2, and from the second cylinder chamber 135, between the third chamber C3 and the fourth chamber C4. Figure 3 and Figure 4 In the exemplary embodiment shown, the piston seal 131 is a V-ring seal. In other exemplary embodiments, the piston seal 131 may be a U-ring, O-ring, flat seal, lip seal, guide ring, etc. These ring seals may be made of polytetrafluoroethylene (PTFE), nitrile rubber, neoprene rubber, ethylene propylene diene monomer (EPDM), fluorocarbon rubber, or combinations thereof.

[0027] In an exemplary embodiment, a compression spring 126 is disposed within a fourth chamber C4, wherein the compression spring 126 contacts a second side 134B of the second piston 134 and a second cylinder chamber end 135B of the second cylinder chamber 135. The compression spring 126 biases the second piston 134 along a first direction away from the second cylinder chamber end 135B of the second cylinder chamber 135 and toward the first cylinder chamber end 135A of the second cylinder chamber 135.

[0028] In several embodiments, the piston-cylinder actuator 104 includes spring supports 127A and 127B. Spring support 127A is defined on a second side of the second piston 134B. Spring support 127B is defined on a second end 135B of the second cylinder chamber 135. Spring supports 127A and 127B guide a spring 126, holding it in a position concentric with the piston shaft 122, and attach it to the second cylinder chamber 135 and the second piston 134.

[0029] The pneumatic inlet valve and relief valve assembly 101 includes a crank slider 124 disposed within a crank slider chamber 120. A piston-cylinder actuator 104 defines the crank slider chamber 120 between a first cylinder chamber 133 and a second cylinder chamber 135. One end of the crank slider 124 is connected to a butterfly plate 103 of the inlet valve 102, and the second end is connected to a piston shaft 122. The crank slider 124 opens and closes the butterfly plate 103 of the inlet valve 102 according to the position of the piston shaft 122. When the piston shaft 122 moves from an idle state to an actuated state, the butterfly plate 103 rotates accordingly from a closed position to an open position within the inlet valve 102. The pneumatic inlet valve and relief valve assembly 101 also includes a relief valve piston cover 130 disposed within a relief valve 106 and connected to the piston shaft 122. The relief valve piston cover 130 is configured to open and close the relief valve 106 through a relief valve inlet 160. When the piston shaft 122 moves from the idle state to the actuated state, the relief valve piston cover 130 is actuated accordingly from the open position to the closed position within the relief valve 106.

[0030] During operation of the pneumatic inlet valve and vent valve assembly 101, the first piston 132 and the second piston 134 are configured to be actuated between an idle state and an actuated state. Figure 3 In the idle state shown, inlet valve 102 is closed to stop the flow of working fluid into the first host 136, and the vent valve inlet 160 of vent valve 106 is open to depressurize the fluid compressor system 100 through vent valve outlet 162. Figure 4 In the actuated state shown, inlet valve 102 is open to allow working fluid to flow into the first host 136, and vent valve inlet 160 is closed to allow pressure buildup in the fluid compressor system 100.

[0031] In an exemplary embodiment, the fluid compressor system 100 is operated between an unloaded state and a loaded state by energizing a first solenoid valve 110 and a second solenoid valve 108 (not shown) via control electrical signals. When the first solenoid valve 110 and the second solenoid valve 108 are de-energized, the fluid compressor system 100 can remain in an unloaded state (or an idle state). In several embodiments, both the first solenoid valve 110 and the second solenoid valve 108 are energized together to change the state of the fluid compressor system 100 to a loaded state. In other embodiments, the first solenoid valve 110 and the second solenoid valve 108 are energized asynchronously.

[0032] The first solenoid valve 110 of the pneumatic inlet valve and vent valve assembly 101 is connected between the butterfly plate 103 and the first main unit 136 and is connected to the fourth chamber C4 via the first connecting pipe 116, such as Figure 2 As shown. At the start of the loading operation, the pneumatic inlet valve and relief valve assembly 101 is idle, with the butterfly plate 103 of the inlet valve 102 closed. When the motor 140 is energized and reaches its maximum speed, a first-stage vacuum pressure is established below the butterfly plate 103 and upstream of the first main unit 136. The first solenoid valve 110 is energized, allowing the first-stage vacuum pressure to flow into the fourth chamber C4 of the piston-cylinder actuator 104.

[0033] When the first-stage vacuum is supplied to the fourth chamber C4, the compression spring 126 is compressed, pulling the second piston 134 toward the second cylinder chamber end 135B of the second cylinder chamber 135. Therefore, the piston shaft 122 moves the relief valve piston cover 130, the first piston 132, the second piston 134, and the crank slider 124 to the actuated position. The relief valve piston cover 130 closes the relief valve inlet 160, allowing the pressure within the fluid compressor system 100 to increase. Simultaneously, the crank slider 124 rotates the disc 103, opening the inlet valve 102 to allow working fluid to flow into the first main unit 136, thereby compressing the working fluid and supplying interstage pressure.

[0034] When the butterfly plate 103 is fully open, the first-stage vacuum is supplied to the fourth chamber C4 in a reduced amount. The actuated state of the piston-cylinder actuator 104 is maintained by the interstage pressure supplied by the first host 136. In an exemplary embodiment, the interstage pressure tap "B" is located between the interstage moisture separator 144 and the second host 138. In other embodiments, the pressure tap "B" is located between the first host 136 and the second host 138. The interstage pressure is supplied to the first chamber C1 and the third chamber C3 via an inline check valve 164 mounted to the inlet port of the second solenoid valve 108 and further via a quick-release valve 112 and through passage 113. The pressure buildup in the first chamber C1 and the third chamber C3 helps the first piston 132 and the second piston 134 maintain the actuated positions of the second cylinder end 133B of the first cylinder chamber 133 and the second cylinder end 135B of the second cylinder chamber 135, respectively. Figure 4 As shown in the exemplary embodiment, when the fluid compressor system 100 is being loaded, the second piston 134 holds the compression spring 126 in the compressed position.

[0035] In an exemplary embodiment, an in-line check valve 164 is connected between the interstage pressure tap "B" and the second solenoid valve 108 to limit the interstage vacuum effect on the first chamber C1 and the third chamber C3 during startup of the fluid compressor system 100 or when the fluid compressor system 100 changes from unloading operation to loading operation.

[0036] In an exemplary embodiment, the pneumatic inlet valve and relief valve assembly 101 further includes a quick-release valve 112 connected via a second connecting pipe 114 between the second solenoid valve 108 and the first chamber C1 and the third chamber C3. When the fluid compressor system 100 is set to unload operation, the second solenoid valve 108 is de-energized and the quick-release valve 112 rapidly releases the pressure buildup in the first chamber C1 and the third chamber C3, thereby allowing the compression spring 126 to push the second piston 134 back together with the piston shaft 122. Figure 3 The idle state shown is in which the inlet valve 102 is closed and the vent valve 106 is open to discharge the pressure buildup in the fluid compressor system 100 through the second-stage vent line "A".

[0037] In an exemplary embodiment, the piston-cylinder actuator includes a vacuum setting screw 128 for manually adjusting the unloading vacuum for different package combinations of the fluid compressor system 100. The linear adjustment set by the vacuum setting screw 128 progressively pushes the piston shaft 122 forward, thereby moving a crank slider 124, one end of which is connected to a disc 103. The setting of the vacuum setting screw can progressively adjust the angular position of the disc 103 to maintain optimal clearance between the disc 103 and the housing of the inlet valve 102.

[0038] In an exemplary embodiment, interstage pressure is supplied to the first chamber C1 and the third chamber C3 via a second solenoid valve 108 to keep the relief valve 106 closed and the compression spring 126 compressed. In such embodiments, a larger piston-cylinder area can be used to balance the frictional forces on the first piston 132 and the second piston 134 to maintain the actuated state. Depending on the available interstage pressure, an additional piston (not shown) with a similar cylinder arrangement can be provided in the piston-cylinder actuator 104. In an exemplary embodiment, the size of the compression spring 126 is selected based on the size of the second cylinder chamber 135 such that the second piston 134 is fully (e.g., completely) retracted during unloading operations.

[0039] In other exemplary embodiments (not shown), the pneumatic inlet valve and vent valve assembly 101 includes a vacuum-assisted spring reset mechanism. In such embodiments, the second solenoid valve 108 includes a release line connected back to the first-stage vacuum pressure for rapidly returning the pneumatic inlet valve and vent valve assembly to its idle state, wherein the compression spring 126 biases the vent valve piston cap 130 to open the vent valve 106.

[0040] In an exemplary embodiment, the fluid compressor system 100 is an oil-free rotary (OFR) screw compressor. In other exemplary embodiments (not shown), the fluid compressor system may be a contact-cooled rotary (CCR) screw compressor, a rotary vane compressor, a reciprocating compressor, a centrifugal compressor, or an axial compressor. In other exemplary embodiments, the pneumatic inlet valve and vent valve assembly 101 may be combined with or modified with other equipment having compression applications, including but not limited to heating, ventilation, and air conditioning (HVAC) systems, refrigeration systems, gas turbine systems, etc.

[0041] Although the subject matter has been illustrated and described in detail in the accompanying drawings and the foregoing description, it should be considered illustrative rather than restrictive. It should be understood that only preferred embodiments are shown and described, and protection is intended for all modifications and variations falling within the spirit of the subject matter. It should be understood that while the use of terms such as preferred, especially, or more preferred in the foregoing description to indicate such described features may be more appropriate, it may not be necessary, and embodiments lacking such features may be considered within the scope of the subject matter, defined by the appended claims. When reading the claims, unless expressly stated otherwise in the claims, the use of words such as “a,” “at least one,” or “at least a portion” is not intended to limit the claims to only one item. Unless expressly stated otherwise, the use of the language “at least a portion” and / or “a portion” may include a portion and / or the entire item. Unless otherwise specified or limited, the terms “installation,” “connection,” “support,” and “linkage,” and their variations, are widely used and cover direct and indirect installation, connection, support, and linking. Furthermore, “connection” and “linkage” are not limited to physical or mechanical connections or links.

Claims

1. A fluid compressor system for compressing a working fluid, comprising: A first host, the first host being operable to receive and compress the working fluid; A second host, which is operable to receive the working fluid from the first host and further compress the working fluid; as well as Pneumatic inlet valve and relief valve assembly, including: An inlet valve is provided for receiving the working fluid into the fluid compressor system, and the inlet valve is configured to regulate the flow rate of the working fluid entering the first host unit. A relief valve, connected to the discharge port of the second main unit, is configured to release pressure within the fluid compressor system. A piston-cylinder actuator, wherein the piston-cylinder actuator is connected to the inlet valve and the relief valve, the piston-cylinder actuator comprising: The first piston is housed within the first cylinder. A second piston is housed within a second cylinder. The first and second pistons are axially connected via a piston shaft. The first cylinder defines a first chamber on a first side of the first piston and a second chamber on a second side of the first piston. The second cylinder defines a third chamber on a first side of the second piston and a fourth chamber on a second side of the second piston. A compression spring, the compression spring being disposed in the fourth chamber, and A relief valve piston cover is disposed within the relief valve, the piston cover being connected to the piston shaft and configured to open and close the relief valve. The first piston and the second piston are configured to be actuated between an idle state and an actuated state, in which the inlet valve is closed to stop the flow of the working fluid into the fluid compressor system and the vent valve is open to depressurize the fluid compressor system; in the actuated state, the inlet valve is open to allow the working fluid to flow into the first host and the vent valve is closed to allow pressure buildup in the fluid compressor system.

2. The fluid compressor system of claim 1, wherein, The pneumatic inlet valve and vent valve assembly also includes a first solenoid valve connected between the inlet valve and the first host, and the first solenoid valve is in communication with the fourth chamber.

3. The fluid compressor system of claim 2, wherein, The first solenoid valve supplies a first-stage vacuum pressure to the fourth chamber of the piston-cylinder actuator, which compresses the compression spring and actuates the first piston and the second piston from the idle state to the actuated state.

4. The fluid compressor system of claim 3, wherein, The pneumatic inlet valve and relief valve assembly also includes a second solenoid valve connected to an interstage pressure tap between the first host and the second host, and the second solenoid valve is in communication with the first chamber and the third chamber.

5. The fluid compressor system of claim 4, wherein, When energized, the second solenoid valve supplies interstage pressure to the first and third chambers of the piston-cylinder actuator, which holds the first and second pistons in the actuated state when the fluid compressor system is being loaded.

6. The fluid compressor system according to claim 5, wherein, The pneumatic inlet valve and relief valve assembly also includes a quick-release valve connected between the second solenoid valve and the first and third chambers. When the fluid compressor system is unloading, the second solenoid valve is de-energized, the quick-release valve is configured to release the pressure buildup in the first and third chambers, and the compression spring pushes the first and second pistons back to the idle state.

7. The fluid compressor system according to claim 1, wherein, The piston shaft is mechanically connected to a crank-slider mechanism that moves the inlet valve between an open and a closed position.

8. The fluid compressor system of claim 1, wherein, The fluid compressor system is an oil-free rotary (OFR) compressor.

9. A pneumatic inlet valve and relief valve assembly for a fluid compressor system, comprising: An inlet valve is provided through which the working fluid enters the fluid compressor system. The inlet valve regulates the flow rate of the working fluid entering the first main unit, which is operable to receive and compress the working fluid. A relief valve, connected to the discharge port of the second main unit, is configured to release pressure within the fluid compressor system. A piston-cylinder actuator, wherein the piston-cylinder actuator is connected to the inlet valve and the relief valve, the piston-cylinder actuator comprising: The first piston is housed within the first cylinder. A second piston is housed within a second cylinder. The first and second pistons are axially connected via a piston shaft. The first cylinder defines a first chamber on a first side of the first piston and a second chamber on a second side of the first piston. The second cylinder defines a third chamber on a first side of the second piston and a fourth chamber on a second side of the second piston. A compression spring, the compression spring being arranged in the fourth chamber, and The first piston and the second piston are configured to be actuated between an idle state and an actuated state, in which the inlet valve is closed to stop the flow of the working fluid into the fluid compressor system and the vent valve is open to depressurize the fluid compressor system; in the actuated state, the inlet valve is open to allow the working fluid to flow into the first host and the vent valve is closed to allow pressure buildup in the fluid compressor system.

10. The pneumatic inlet valve and relief valve assembly according to claim 9 further includes a first solenoid valve connected between the inlet valve and the first host, the first solenoid valve being in communication with the fourth chamber.

11. The pneumatic inlet valve and relief valve assembly according to claim 10, wherein, The first solenoid valve supplies a first-stage vacuum pressure to the fourth chamber of the piston-cylinder actuator, which compresses the compression spring and actuates the first piston and the second piston from the idle state to the actuated state.

12. The pneumatic inlet valve and relief valve assembly according to claim 11, further comprising a second solenoid valve connected to an interstage pressure tap between the first host and the second host, the second solenoid valve being in communication with the first chamber and the third chamber.

13. The pneumatic inlet valve and bleed valve assembly of claim 12, wherein, When energized, the second solenoid valve supplies interstage pressure to the first and third chambers of the piston-cylinder actuator, which holds the first and second pistons in the actuated state when the fluid compressor system is being loaded.

14. The pneumatic inlet valve and relief valve assembly according to claim 13, further comprising a quick-release valve, the quick-release valve being connected between the second solenoid valve and the first chamber and the third chamber, wherein, When the second solenoid valve is de-energized, the quick-release valve is configured to release the pressure buildup in the first and third chambers, and the compression spring pushes the first and second pistons to the idle state.

15. The pneumatic inlet valve and bleed valve assembly of claim 9, wherein, The piston shaft is mechanically connected to a crank-slider mechanism that moves the inlet valve between an open and a closed position.

16. The pneumatic inlet valve and bleed valve assembly of claim 9, wherein, The fluid compressor system is an oil-free rotary (OFR) compressor.

17. A fluid compressor system for compressing a working fluid, comprising: A first host, the first host being operable to receive and compress the working fluid; A second host, which is operable to receive the working fluid from the first host and further compress the working fluid; as well as Pneumatic inlet valve and relief valve assembly, including: An inlet valve is provided for receiving the working fluid into the fluid compressor system, and the inlet valve is configured to regulate the flow rate of the working fluid entering the first host unit. A relief valve, connected to the discharge port of the second main unit, is configured to release pressure within the fluid compressor system. A piston-cylinder actuator, wherein the piston-cylinder actuator is connected to the inlet valve and the relief valve, the piston-cylinder actuator comprising: The first piston is housed within the first cylinder. A second piston, housed within a second cylinder, is axially connected to the first piston via a piston shaft. The first cylinder defines a first chamber on a first side of the first piston and a second chamber on a second side of the first piston. The second cylinder defines a third chamber on a first side of the second piston and a fourth chamber on a second side of the second piston. A compression spring, wherein the compression spring is disposed in the fourth chamber, The first piston and the second piston are configured to be actuated between an idle state and an actuated state, in which the inlet valve is closed to stop the flow of the working fluid into the fluid compressor system and the vent valve is open to depressurize the fluid compressor system; in the actuated state, the inlet valve is open to allow the working fluid to flow into the first host and the vent valve is closed to allow pressure buildup in the fluid compressor system.

18. The fluid compressor system of claim 17, wherein, The pneumatic inlet valve and vent valve assembly also includes a first solenoid valve connected between the inlet valve and the first host, and the first solenoid valve is in communication with the fourth chamber.

19. The fluid compressor system of claim 18, wherein, The first solenoid valve supplies a first-stage vacuum pressure to the fourth chamber of the piston-cylinder actuator, which compresses the compression spring and actuates the first piston and the second piston from the idle state to the actuated state.

20. The fluid compressor system according to claim 19, wherein, The pneumatic inlet valve and relief valve assembly further includes a second solenoid valve connected to an interstage pressure tap between the first main unit and the second main unit. The second solenoid valve communicates with the first chamber and the third chamber, and wherein, when energized, the second solenoid valve supplies interstage pressure to the first chamber and the third chamber of the piston-cylinder actuator, the interstage pressure holding the first piston and the second piston in the actuated state when the fluid compressor system is being loaded.

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