Flow control valve, for example expansion valve for refrigeration system

Abstract

A pressure-balanced piston-type flow control valve having a mechanical fail-safe function, a balanced passage, and a balanced pilot valve is provided. The invention relates to a flow control valve (1; 100), for example an expansion valve for a refrigeration system, of the pressure-balanced piston type and having a mechanical fail-safe functionality. The valve (1; 100) comprises a valve body (10), a piston (60) and a valve driver (30) for controlling a fluid flow from a fluid inlet (11) through a valve seat (13) to a fluid outlet (15) by displacing the piston (60) relative to the valve seat (13). The piston (60) protrudes into the balancing chamber (20) with a driver-side end portion (61) and includes a balancing passage (70) having a first flow resistance. In order to provide a reliable fail-safe functionality for a valve (1; 100) in a cost-effective manner, the valve comprises: a fluid drain (25) from the inlet pressure chamber (12) and / or the fluid inlet (11) to the equalization chamber (20), the fluid drain (25) being separate from the equalization passage (70) and having a second flow resistance greater than the first flow resistance; and an equalization pilot valve (80) for opening and closing the equalization passage (70).

Description

[0001] The invention relates to a flow control valve, for example an expansion valve for a refrigeration system, which is pressure balanced piston type and has a mechanical fail-safe functionality.

[0002] The cooling system can comprise an evaporator, a condenser, an expansion valve and a compressor for circulating refrigerant. The expansion valve can be such a flow control valve and can be actuated by a motor.

[0003] To require a less powerful motor, the valve can be pressure balanced piston type. An example is shown in US 9,494,253 B2. It comprises a piston for engaging a valve seat. The piston is displaceable by a motor axially along a longitudinal direction. A balancing chamber is formed at the side of the piston opposite the valve seat. An equalization passage is formed between the balancing chamber and a region downstream of the valve seat. The equalization passage allows the balancing pressure in the balancing chamber to adapt to the pressure downstream of the valve seat. The axial force exerted by the balancing chamber onto the piston and the pressure below the valve seat can be partially compensated.

[0004] If the power supply for providing electrical energy fails ("power failure"), the motor is no longer powered. The motor and the valve can remain in a position in which the valve is open. Refrigerant can condense in the cold evaporator to a fluid. When the external power supply is started again, there is a high risk that the compressor sucks in the fluid and is damaged.

[0005] According to a method to avoid these problems, the controller for the motor can comprise an accumulator. The accumulator is used to close the valve in case of a failure of the external power supply. However, this solution is expensive. Further, it can be necessary to replace the accumulator periodically. This leads to additional maintenance work and costs.

[0006] A pressure balanced piston type flow control valve with a mechanical fail-safe functionality is disclosed in US 6,997,430 B2. A pressure spring presses the piston towards the valve seat. To keep the valve reliably closed in case of a power failure, the spring has to be strong. It has to exert enough force to keep the piston in abutment with the valve seat, even if pressure fluctuations occur. The motor has to be relatively strong and requires high power to open the valve.

[0007] Another expansion valve is known from US 4,911,401 A. It utilizes a piston assembly which is balanced to high pressure by a bleed system through the piston. A return spring pushes the piston assembly into engagement with a push rod assembly.

[0008] It is an object of the invention to provide a cost-effective flow control valve with reliable fail-safe functionality.

[0009] This problem is solved by a flow control valve, for example an expansion valve, especially for a refrigeration system, having the features according to claim 1.

[0010] The flow control valve is a pressure balanced piston type and has a mechanical fail-safe functionality. The valve comprises:

[0011] a valve body having a fluid inlet, an inlet pressure chamber fluidly connected with the fluid inlet, a fluid outlet, a valve seat arranged between the inlet pressure chamber and the fluid outlet, and a balance chamber;

[0012] a piston; and

[0013] a valve drive for controlling a fluid flow from the fluid inlet through the valve seat to the fluid outlet by displacing the piston relative to the valve seat in an axial direction, wherein the valve drive comprises a motor and a drive member drivable by the motor for axially driving the piston,

[0014] wherein the piston protrudes with a drive side end portion into the balance chamber and comprises a balance passage from the drive side end portion to an equalization opening fluidly connected with the fluid outlet, the balance passage having a first flow resistance,

[0015] wherein the valve comprises a fluid leak-off from the inlet pressure chamber and / or the fluid inlet to the balance chamber, wherein the fluid leak-off is separate from the balance passage and has a second flow resistance greater than the first flow resistance, and

[0016] wherein the valve comprises an equalization pilot valve for opening and closing the balance passage.

[0017] The invention allows to exploit several synergistic effects. The mechanical fail-safe functionality ensures a high safety.

[0018] When the equalization pilot valve is open, the "equalization" functionality is enabled. The pressure in the balance chamber (the equalization pressure) is at least substantially adapted to the pressure downstream of the valve seat. The second flow resistance is greater than the first flow resistance, ensuring that when the equalization pilot valve is open, the equalization pressure is influenced less by the fluid leak-off than by the balance passage. The valve drive only needs to provide a small force to open and close the valve. Further, due to the balance passage, the valve is less influenced by pulsations of the fluid flow through the valve.

[0019] In the invention, the balance passage is closable. Whenever it is not needed or even disadvantageous, the "equalization" functionality can be deactivated by the equalization pilot valve. Then, the fluid leak-off increases the equalization pressure.

[0020] In conventional pressure-balanced piston-type valves without a balancing pilot valve, the balancing pressure is always substantially the same as the outlet pressure, especially when the valve is closed. The total axial force exerted by the fluid on the piston (towards the valve seat) is generated by multiplying the pressure difference between the inlet and outlet pressures when the valve is closed by the (typically annular) contact area between the valve seat and the piston. In this respect, only this small contact area contributes to the total axial force. Therefore, this total axial force holding the valve closed is quite small, and conventional valves are prone to accidental opening due to pressure fluctuations and valve chatter. With the present invention, for example, when the flow control valve is closed, the balancing pilot valve can be closed. The balancing chamber is then actuated by the inlet pressure through a fluid vent. In this case, the total axial force exerted by the fluid on the piston towards the valve seat is generated by multiplying the pressure difference (between the inlet and outlet pressures) by the sum of the contact area between the valve seat and the piston and the area enclosed by said contact area. The latter enclosed area is typically much larger than the contact area. The valve according to the invention is held in the desired state much more firmly and reliably by increasing the balancing pressure via the vent when the balancing pilot valve is closed. This improves fail-safe functionality. Any device used to push the valve to the desired state (e.g., closed) to provide fail-safe functionality needs to be less powerful. They can be smaller, lighter, and cheaper. Because fail-safe functionality requires less powerful devices, opening and closing the valve (when the equalizing pilot valve is open) requires less driving force. Valve actuators can be less powerful, smaller, lighter, and cheaper.

[0021] In summary, the present invention provides a cost-effective flow control valve with reliable fail-safe functionality.

[0022] Mechanical fail-safe functionality can be configured to automatically close the valve (normally closed valve), automatically open the valve (normally open valve), or automatically bring the valve to another predetermined position / state (e.g., to a predetermined opening degree between the closed state and the fully open state) in the event of a power failure.

[0023] According to one aspect, flow control valves allow for so-called forced opening by a motor in the absence of a pressure differential. The movement of the piston is driven by the motor, rather than by relying on a pressure differential.

[0024] In one embodiment, the motor is an electric motor. Specifically, the motor can be a stepper motor. Stepper motors allow for precise adjustment of the valve opening. Additionally or alternatively, the valve actuator may include a conversion mechanism for converting rotational movement provided by the motor (e.g., a stepper motor) into axial movement of the piston. This allows for the use of a rotary motor type.

[0025] Other types of electric motors may also be used. The electric motor must be configured to be electrically stationary in several positions (e.g., any position between the fully open and closed state of the valve). Optionally, the valve actuator (e.g., an electric motor) may include, for example, a position sensor for detecting the position of the piston.

[0026] (Stepper) motors can be of the type with low positioning torque. In particular, the motor can be a variable reluctance stepper motor. A variable reluctance stepper motor will not produce any positioning torque (at least not a significant one) when not powered. When the rotor is rotated by an external force, especially when the resilient reset element (see below) causes the valve actuator to rewind, there are no permanent magnets in the rotor that generate current in the stator. In other words, the motor does not provide resistance to the rewinding caused by the permanent magnets. Therefore, a weaker resilient reset element can be used. It can be cheaper, smaller, and lighter. If the resilient reset element is weak, a lower-powered motor is sufficient to overcome the force (in normal operation) of the resilient reset element, for example, used to open a valve. The motor can also be cheaper, smaller, lighter, and more efficient.

[0027] Stepper motors with rotors including permanent magnets can also be used. For example, the motor can be a hybrid stepper motor. A balance is maintained between the positioning torque generated by the rewinding speed (and the corresponding rotational speed of the rotor) applied by the elastic reset element, the resistance in the motor controller, and the maximum permissible time for the valve to remain in a predetermined state through mechanical fail-safe functionality in the event of a power failure.

[0028] According to one aspect, at least the rotor of the motor (e.g., a stepper motor) is housed in a motor chamber, which is fluidly connected to a balancing pressure chamber. This improves the efficiency of the valve.

[0029] The stator can be housed within the motor chamber. This further improves efficiency and facilitates manufacturing. Alternatively, the stator is external. During operation, the stator is not exposed to fluids such as refrigerant. The walls of the motor chamber (e.g., thin-walled tubes) separate the external stator from the motor chamber and thus from the fluid.

[0030] Any component exposed to a fluid should be resistant to the fluid.

[0031] In one embodiment, the drive member and the piston form an equalization pilot valve, and the mechanical connection between the drive member and the piston allows for limited relative axial displacement of the drive member relative to the piston for opening and closing the equalization pilot valve.

[0032] Specifically, the equalizing pilot valve can be opened and closed by axial displacement of the drive member relative to the piston. Once the limited relative axial displacement is exhausted, further axial movement of the drive member relative to the piston automatically (in the same direction) drives the piston.

[0033] Mechanical connections between drive components may include hook arrangements between the drive component and the piston.

[0034] In one embodiment, the valve includes a labyrinth seal between the piston and the valve body in the intermediate portion of the piston between the inlet pressure chamber and the balance chamber. The balance piston is typically sealed with a lip seal or piston rings. This results in risks depending on the differential pressure and swelling friction of the polymer, as well as stick-slip behavior. The labyrinth seal provides very low friction. This synergistically contributes to the advantages that the resilient resetter element can be less robust, and that less motor force is required to open and close the valve.

[0035] Labyrinth seals can form part of a fluid venting channel. If a pressure differential exists along the labyrinth seal, some leakage occurs. This is typically considered disadvantageous. The present invention utilizes this leakage in a synergistically beneficial manner to form or at least constitute part of a fluid venting section. In particular, the labyrinth seal can (at least substantially) define a second flow resistance.

[0036] According to one aspect, the valve may include a resilient return element for automatically bringing a piston to a predetermined position when the motor is not powered. For example, the resilient return element can be compressed as the piston moves away from the predetermined position. The compression can increase with the increase in piston displacement from the predetermined position. When the piston is in the predetermined position, the resilient return element can be compressively preloaded. For example, the predetermined position may correspond to the closed state of the valve. The predetermined position is the abutment position of the piston, in which the piston abuts against and seals against the valve seat. The resilient force provided by the resilient return element is configured (e.g., sufficiently high) to bring the piston to the predetermined position in the event of a power failure. Conversely, the motor must have sufficient power to overcome, for example, during valve opening, friction regarding piston movement, axial forces exerted on the piston by the fluid, and the force necessary to compress the resilient return element to open the valve from the closed state. The resilient element may include a spring-like resilient element, such as an axial spring (e.g., a helical spring) and / or a torsion spring (e.g., a flat torsion spring or a circular helical torsion spring).

[0037] The resilient return element can act on a valve actuator. For example, the resilient return element can act on any of the following: a rotor, a motor shaft, a main shaft, and a drive component. At least one end of the resilient return element can be fixed relative to the valve body in a rotational sense and / or axially.

[0038] In one embodiment, the drive member is threadedly engaged with and can be driven by the spindle, which can be rotated by a motor. The drive member may be a nut member.

[0039] The pitch of the threaded connection between the drive component and the spindle can be at least 3 mm per revolution. A high pitch results in greater axial movement of the drive component per spindle revolution. This ensures that if motor force is lost (in the event of a power failure), only a small force is required to rotate the spindle backward.

[0040] The spindle may include a thread having at least one thread lead for threadedly engaging a drive member. In particular, the thread of the spindle may include several thread leads (i.e., a "multi-start thread").

[0041] Rotation of the drive member relative to the valve body can be prevented, for example, by spline engagement with the valve body. The drive member may include anti-rotation fins guided in axial slots within the valve body.

[0042] According to one aspect, the first end of the resilient reset element can be rotatedly coupled (e.g., directly) to the spindle to prevent rotation of the first end relative to the spindle. The second end of the resilient reset element can be rotatedly coupled to the valve body, for example, directly and / or via a drive member.

[0043] According to another aspect, the first end of the resilient reset element can be axially abutted (e.g., directly) against the drive member in the axial direction. The second end of the resilient reset element can be axially abutted (directly) against the valve body.

[0044] In one embodiment, the resilient reset element is a torsion spring that acts directly on the spindle. This ensures exceptionally low friction and easy valve reset to a predetermined state.

[0045] In one respect, the balancing pilot valve opens before the piston moves away from a predetermined position, for example, before the piston is lifted from the valve seat to open the valve. The balancing function is activated before the piston begins axial movement. Only a small valve actuation force (motor force) is required to open the valve.

[0046] According to one aspect, the valve is configured such that (in operation) when the motor is powered to drive the piston away from its predetermined position, the equalizing pilot valve automatically opens. The equalizing pilot valve can open by an initial (e.g., axial) movement of the drive member relative to the piston when the motor is powered to drive the piston away from its predetermined position. Specifically, the equalizing pilot valve can open by an initial (e.g., axial) movement of the drive member relative to the piston before the drive member actuates the piston when the motor is powered to drive the piston away from its predetermined position.

[0047] In one embodiment, the piston includes a protruding portion at its outlet-side end, opposite the drive-side end portion in the axial direction, the protruding portion having an outer circumference corresponding to the inner circumference of the valve seat. The protruding portion may have a (at least substantially) cylindrical basic shape and / or a conical basic shape.

[0048] Furthermore, the protrusion may have at least one grooved portion, wherein, when the piston is removed from the valve seat, a flow passage from the inlet pressure chamber through the valve seat to the fluid outlet is defined between the at least one grooved portion and the valve seat. The size of the flow passage may increase with the increase of piston displacement away from its adjacent position.

[0049] According to one aspect, the piston may include a supplemental balancing passage for establishing a fluid connection between the inlet pressure chamber and the balancing passage when the piston is lifted from the valve seat. The supplemental balancing passage may include a channel opening disposed in a protruding portion of the piston, preferably external to any of the grooved portions. This ensures that the valve actuation force (especially motor force) used to displace the piston is relatively uniform across the piston stroke.

[0050] In one embodiment, within a predetermined range of piston movement in the axial direction, the effective flow cross-section of the supplementary balancing passage gradually increases with increasing axial displacement of the piston toward the drive end side. This feature ensures that the pressure in the balancing passage, and therefore the balancing chamber, increases more rapidly during opening—that is, more rapidly than the pressure at the balancing opening—but in a smooth manner. This helps ensure that even more uniform valve drive force (especially motor force) is required to displace the piston within the predetermined range of piston movement. The grooves may be arranged on the exterior of any of the grooved portions.

[0051] The supplemental equalization passage can have a groove formed in the region including the channel opening on the outer circumference of the protrusion, wherein the groove extends (substantially) along the axial direction and tapers as the cross-sectional diameter increases toward the outlet side. This embodiment is relatively easy to manufacture but still has the desired characteristics.

[0052] In particular, the groove can taper as the depth increases toward the outlet side.

[0053] The external opening of the supplementary equalization passage can be arranged at the outlet end portion of the groove.

[0054] In one embodiment, the valve actuator includes a gearbox between the motor and the drive component. Specifically, the gearbox may be located between the motor and the spindle.

[0055] The gear ratio (revolutionary spindle:revolutionary motor) can be less than 1:1, for example, in the range of 1:1.5 to 1:4, such as 1:2. If the resilient reset element acts on a component downstream of the gearbox in the valve actuator, the motor requires less power to overcome the resilient force of the resilient reset element. The resilient force of the resilient reset element is sufficient to overcome the overall resistance of the valve actuator to resetting to the predetermined position.

[0056] In another embodiment, the spindle is directly coupled to the motor shaft of the motor in a rotational sense. This reduces complexity and facilitates production.

[0057] The spindle, gearbox, and / or rotor may be supported by a guide support. The guide support may be configured to absorb axial loads.

[0058] According to one aspect, the valve is configured such that (in operation) the balancing pilot valve automatically closes the balancing passage at least when the following occurs.

[0059] - The valve is in a predetermined state (e.g., when the piston is not in a predetermined position), and at the same time,

[0060] - The motor is not powered.

[0061] The valve can be configured such that (during operation) the increased balancing pressure when the equalizing pilot valve is closed helps to maintain the valve in a predetermined state (e.g., hold the piston in a predetermined position) when the motor is not powered. It can also be configured such that when the equalizing pilot valve is open, the reduced balancing pressure decreases the motor force required to move the piston axially.

[0062] At least a portion of the equalizing pilot valve may be mechanically coupled to the resilient reset element, for example, via a drive member and / or a spindle. The valve may be configured such that when the motor is not powered, the resilient reset element actuates the equalizing pilot valve to close.

[0063] This problem is further solved by a refrigeration system including a flow control valve according to the invention.

[0064] The embodiments, modifications, and advantages described regarding the flow control valve can be applied accordingly, and vice versa.

[0065] A refrigeration system may be a cooling system or a heat pump. A refrigeration system may include at least one, several, or all of the following: an evaporator, a condenser, an expansion device (e.g., including the disclosed valves), and a compressor.

[0066] The flow control valve according to the present invention can be used as an expansion device.

[0067] Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0068] Figure 1 A longitudinal section of a first embodiment of the flow control valve according to the invention in the closed state is shown;

[0069] Figure 2 It shows the state when fully open. Figure 1 The longitudinal section of the valve;

[0070] Figure 3 It shows that it is in the off state (e.g.) Figure 1 (middle) the balance chamber around Figure 1 and Figure 2 The enlarged longitudinal cross-sectional area of ​​the valve;

[0071] Figure 4 This shows the end of the first stage of valve opening. Figure 3 The area;

[0072] Figure 5 This shows the valve in its fully open state. Figure 3 and Figure 4 The area;

[0073] Figure 6 It shows that it is in the off state (e.g.) Figure 1 (middle) Enlarged longitudinal section area around the valve seat;

[0074] Figure 7 This shows the valve in its fully open state. Figure 6 The area;

[0075] Figure 8 The area around the valve seat during the transition between the closed and fully open states is shown. Figure 1 and Figure 2 The valve has an even larger cross-section;

[0076] Figure 9 The axial displacement of the piston is shown. Figure 1 and Figure 2 The relationship between the effective flow cross sections of the valve's supplementary equalization path;

[0077] Figure 10 It shows Figure 1 and Figure 2 A perspective view of the piston-driven side portion of the valve;

[0078] Figure 11 A longitudinal section of a second embodiment of the flow control valve according to the present invention is shown when it is in the closed state;

[0079] Figure 12 It shows Figure 1 , Figure 2 and Figure 11 A side view of the lower part of the piston of the valve in the middle;

[0080] Figure 13 A longitudinal section of the lower portion of the piston is shown;

[0081] Figure 14 It shows Figure 11 A three-dimensional view of the valve's drive component;

[0082] Figure 15 A cross-sectional view of the driving component is shown;

[0083] Figure 16 It shows a motor and gearbox. Figure 11 A cross-sectional view of the upper part of the valve;

[0084] Figure 17 It shows the use of Figure 11 A circular helical torsion spring in the valve's elastic reset element; and

[0085] Figure 18 An alternative flat torsion spring is shown.

[0086] Figure 19 A longitudinal section of a third embodiment of the flow control valve according to the present invention is shown when it is in a predetermined state with a predetermined opening degree between a closed state and a fully open state.

[0087] Figure 20 The diagram shows the area around the switching mechanism when the valve is fully open, i.e., when the piston is fully retracted. Figure 19 The enlarged cross-section of the valve; and

[0088] Figure 21 The diagram shows the area around the switching mechanism when the piston is adjacent to the valve seat. Figure 19 The enlarged cross-section of the valve.

[0089] Figure 1 and Figure 2 A first embodiment of the flow control valve 1 according to the present invention is shown. Figure 1 This shows that valve 1 is in the closed state. Figure 2 It is shown to be in the fully open position. Valve 1 could be an expansion valve used in a refrigeration system.

[0090] Valve 1 includes a valve body 10 having a fluid inlet 11. Fluid (e.g., refrigerant from a refrigeration system) can flow into the valve body 10 through the fluid inlet 11. The valve body 10 may include a fluid inlet port 11a forming the fluid inlet 11. Further, the valve body 10 has a fluid outlet 15. Fluid can flow out of the valve body 10 through the fluid outlet 15. The valve body 10 may include a fluid outlet port 15a forming the fluid outlet 15 (for regulated flow rates). The flow direction of the fluid can be defined in operation from the fluid inlet 11 to the fluid outlet 15. The valve body 10 may include an inlet pressure chamber 12 (directly fluidly connected to the fluid inlet 11) and / or an outlet pressure chamber 14 (directly fluidly connected to the fluid outlet 15).

[0091] The valve body 10 includes a valve seat 13 disposed between the fluid inlet 11 and the fluid outlet 15 along the flow direction. The valve seat 13 may be disposed between the inlet pressure chamber 12 and the fluid outlet 15, particularly between the inlet pressure chamber 12 and the outlet pressure chamber 14.

[0092] The valve body 10 may include several parts. In this example, it includes a lower housing section 2, a seat insert 3, a guide insert 4, an intermediate housing section 5, and a motor housing section 6. The seat insert 3, guide insert 4, intermediate housing section 5, and motor housing section 6 are fixed relative to the lower housing section 2. They can be releasably fixed relative to the lower housing section 2 to allow for maintenance. For example, the seat insert 3 may be fixed to the guide insert 4, the motor housing section 6 may be fixed to the intermediate housing section 5, and the intermediate housing section 5 may be releasably fixed to the lower housing section 2, thereby holding the guide section 4 and the seat insert 3 in place within the lower housing section 2.

[0093] A fluid inlet port 11a and a fluid outlet port 15a are formed in the lower housing section 2. A seat insert 3 is inserted into the lower housing section 2 and includes a valve seat 13. The valve seat 13 is formed at the downstream sidewall 3a of the seat insert 3. The downstream sidewall 3a separates the outlet pressure chamber 14 and the inlet pressure chamber 12. The valve body 10 (here, the seat insert 3) may include a fluid passage 13a from the valve seat 13 (on the side having the inlet pressure chamber 12) to the outlet pressure chamber 14 (see [link to documentation]). Figure 2 (Referring to the reference numerals in the figures). In this example, the fluid passage 13a has a conical shape. A sealing device may be provided between the seat insert 3 (especially the downstream sidewall 3a) and the lower housing section 2. The valve seat 13 may protrude into the inlet pressure chamber 12 in the axial direction L. The valve seat 13 and / or the fluid passage 13a may have a shape that is rotationally symmetrical about the central axis C of the piston 60 (see Figure 13). Figure 8The central axis C is parallel to the axial direction L. In this embodiment, the valve seat 13 is formed on a protrusion having a tapered outer circumferential surface. The protrusion may have a rotationally symmetric shape about the central axis C.

[0094] Valve 1 includes a piston 60 that is movable in the axial direction L. When valve 1 is closed (in the closed state), piston 60 abuts against and seals against valve seat 13. Figure 1 and Figure 6 This situation is illustrated. Piston 60 is in the "adjacent position." Therefore, direct fluid flow from inlet pressure chamber 12 to outlet 15 (i.e., direct fluid flow from inlet pressure chamber 12 to outlet pressure chamber 14) is prevented. Figure 2 and Figure 7 The fully open state shown is the opposite, with no flow passage 67 between the piston 60 and the valve seat 13.

[0095] When valve 1 is opened, piston 60 is lifted away from valve seat 13. In other words, piston 60 moves and disengages from valve seat 13. Figure 2 , Figure 5 and Figure 7 This pertains to the scenario where valve 1 is in its fully open position. Piston 60 shifts away from its adjacent position along the axial direction L by the maximum stroke MS (see...). Figure 5 ,and Figure 3 (Compared). Piston 60 is in the "fully retracted" position. The maximum stroke MS of piston 60 corresponds to its displacement between its adjacent position and its fully retracted position.

[0096] Valve 1 includes a valve actuator 30 for moving piston 60 along the axial direction L.

[0097] Valve actuator 30 includes motor 31. Figure 1 and Figure 2 In the valve 1 shown, the motor 31 is a stepper motor, more specifically a variable reluctance stepper motor with a soft iron motor. The motor 31 has a motor shaft 35, a rotor 33 fixed to the motor shaft 35 at least in a rotational sense, and a stator 34. The rotor 33 (together with the motor shaft 35) is housed within a motor chamber 32. The motor chamber 32 is in fluid connection to a balance chamber 20. The stator 34 includes coils.

[0098] exist Figure 1 and Figure 2In the illustrated embodiment, the stator 34 is circumferentially arranged around the rotor 33 outside the motor chamber 32. A valve body 10 (i.e., motor housing section 6) separates the stator 34 from the rotor 33. The valve body 10 also separates the stator 34 from the fluid. The stator 34 is located outside the valve body 10. This method is advantageous when the fluid (e.g., refrigerant) is flammable, explosive, and / or corrosive. For example, Figure 1 and Figure 2 The embodiments shown are particularly suitable for refrigeration systems in which the refrigerant includes ammonia (NH3).

[0099] The valve actuator 30 further includes a spindle 40 coupled to the motor 31. Figure 1 and Figure 2 In the embodiment shown, the spindle 40 is directly connected to the motor shaft 35 in a rotational sense.

[0100] The conversion mechanism 45 of the valve actuator 30 converts the rotational movement of the spindle 40 (relative to the valve body 10) into axial movement (relative to the valve body 10). The spindle 40 has a multi-start external thread 41 that threadedly engages with the internal thread 51 of the drive member 50. The drive member 50 is prevented from rotating relative to the valve body 10 by an anti-rotation mechanism 49.

[0101] In this embodiment, piston 60 is at least axially connected to drive member 50 via mechanical coupling 55. If drive member 50 is axially displaced by motor 31 (by rotation of spindle 40), drive member 50 actuates piston 60 at least when the relative axial displacement of drive member 50 relative to piston 60 exceeds a finite relative axial movement. Therefore, piston 60 can be axially displaced by motor 31 via rotation of spindle 40 and corresponding axial displacement of drive member 50.

[0102] The mechanical coupling 55 between the drive member 50 and the piston 60 allows for a limited relative axial displacement of the drive member 50 relative to the piston 60. This limited relative axial displacement can be less than the maximum stroke MS. For example, it may correspond to at most 10% of the maximum stroke MS.

[0103] According to the first embodiment (see...) Figure 1 and Figure 2 The mechanical coupling 55 in valve 1 can be connected to the valve according to the second embodiment (see...). Figure 11 The mechanical connection in valve 100 is the same as that in valve 100. Therefore, it is also considered that... Figure 10 , Figure 14 and Figure 15 The mechanical coupling 55 is described in more detail. This mechanical coupling includes a hook structure 55 at the drive members 50, 150, which engages with a first flange 54 formed at the drive-side end portion 61 of the piston 60. The hook structure 54 includes a receiving recess 54a for receiving the end 61a and the first flange 57 (see [link to relevant documentation]).Figure 14 and Figure 15 The receiving recess 54a is limited by the shoulder 54b. If the proximal displacement of the drive members 50, 150 relative to the piston 60 has reached the end of a limited relative axial movement, the shoulder 54b engages the first flange 57. The piston 60 follows any further proximal movement of the drive member 50 relative to the valve body 10. "Proximal" can mean opposite in the axial direction L and not adjacent to the valve seat 13 (in...). Figures 1 to 8 and Figures 11 to 13 (Central upward). "Distal" can refer to the adjoining point on valve seat 13 in the axial direction L (in... Figures 1 to 8 and Figures 11 to 13 (Middle to bottom).

[0104] The driver-side end portion 61 may further include a second flange 59 and a groove 58, the second flange being spaced apart from the first flange 57, and the groove being formed between the first flange 57 and the second flange 59 (see [link]). Figure 10 The groove 58 is inserted into the slit within the shoulder 54b (see...). Figure 14 and Figure 15 The width of the groove 58 in the axial direction L can be greater than the sum of the limited relative axial movement and the wall thickness of the shoulder 54b along the axial direction L. This ensures a tight seal between the sealing member 53 and the end 61a when the drive member 50 is forced to abut the piston 60 distally, for example due to the motors 31, 131 and / or the reset elements 43, 143, 243.

[0105] Valve 1 is a pressure-balanced piston type. The valve includes a balancing chamber 20. The actuator-side end 61 of piston 60 protrudes into the balancing chamber 20 along the axial direction L. Piston 60 extends along the axial direction L. The end of piston 60 opposite to the balancing chamber 20 along the axial direction L can be referred to as the outlet-side end of piston 60. A protrusion 64 is formed at the outlet-side end. At least when valve 1 is closed, the outlet-side end of piston 60 protrudes through valve seat 13. The protrusion 64 then protrudes through valve seat 13 into fluid passage 13a (see...). Figure 6 ).

[0106] The diameter of the piston 60 contacting the valve seat 13 (nozzle seal diameter) is at least substantially the same as, i.e., nearly the same (e.g., the difference in diameter may be less than 10%) or identical to, the effective diameter of the piston 60 in the balance chamber 20. According to one aspect, the nozzle seal diameter is at least 1%, and possibly up to 10%, larger than the effective diameter of the piston 60 in the balance chamber 20. If the valve 1 is closed, this helps the piston 60 to securely abut against the valve seat 13.

[0107] A balancing passage 70 is formed in the piston 60. The balancing passage extends along the axial direction L from the actuator-side end 61 to the protrusion 64 within the piston 60. The balancing passage has a balancing chamber opening 71 at the actuator-side end 61 and a balancing opening 72 at the protrusion 64. More specifically, the balancing chamber opening 71 is formed in the actuator-side end 61a of the piston 60.

[0108] At least when valve 1 is closed, and possibly at least when piston 60 does not move away from its adjacent position beyond one-third (in some embodiments: three-quarters) of its maximum stroke MS, the equalization opening 72 is located downstream of valve seat 13. The equalization opening 72 is always in fluid communication with fluid outlet 15. If valve 1 is closed, the equalization opening is subjected to the outlet pressure applied at fluid outlet 15.

[0109] The equalization pilot valve 80 of valve 1 is configured to open and close the equalization passage 70, that is, to enable and disable the direct fluid communication between the equalization chamber 20 and the equalization opening 72 (and thus the "direct" pressure adaptation between the equalization chamber 20 and the outlet 15 via the equalization passage 70).

[0110] The equalizing pilot valve 80 is formed by the drive end side portion 61 of the piston 60 and the piston side end (in the axial direction L) of the drive member 50. In valves 1 and 100 according to exemplary embodiments, the drive members 50 and 150 include a sealing member 53, and the equalizing pilot valve 80 is formed between the drive end side end 61a of the piston 60 and the sealing member 53 facing the piston 60. The sealing member 53 may be arranged in a sealing member mount 53a and fixed by a retaining ring 53c that engages with an annular groove 53b formed in the sealing member mount 53a.

[0111] In the closed state of valve 1 (e.g.) Figure 1 and Figure 3 As shown), the drive member 50 abuts the piston 60 distally (i.e., toward the valve seat 13 in the axial direction L), thereby closing the balancing passage 70. In particular, the sealing member 53 abuts the end 61a of the piston 60, seals against the end 61a, and closes the balancing chamber opening 71.

[0112] The piston 60 includes a main rod 60a and a lower portion 60b. The lower portion 60b is fixed to the main rod 60a, for example, by a threaded engagement 60c. The lower portion 60b includes an outlet-side end with a protrusion 64. The main rod 60a includes a driver-side end 61 protruding into the balancing pressure chamber 20. The main rod 60a also includes a middle portion 62 of the piston 60. At least a portion of the middle portion 62 is axially movably guided in a rod guide passage 3b of the valve body 10 (between the balancing chamber 20 and the inlet pressure chamber 12). Here, the rod guide passage 3b is formed in the guide insert 3.

[0113] The intermediate portion 62 guided in the rod guide channel 3b can have a diameter in the range of 3 mm to 12 mm (e.g., 6 mm) (referred to as the piston diameter DP, see [link]). Figure 5 Depending on the required valve size, the diameter can be larger or smaller. The effective area of ​​piston 60 in the balancing chamber 20 is the area that the balancing pressure can be multiplied to calculate the area of ​​the distal force applied to piston 60 by the balancing pressure (possibly if the balancing pilot valve 80 is closed or if the balancing pilot valve 80 is open but the area of ​​the balancing chamber opening 71 is ignored). In this embodiment, the effective area (also known as the balancing area) can be readily obtained from the piston diameter DP. The balancing pressure also acts on the drive member 50 and in the motor chamber 32, such that portions of the valve actuator 30 (especially the motor shaft 35, main shaft 40, and drive member 50) can contribute to applying the "distal force applied to piston 60 by the balancing pressure" (also known as the balancing force) to piston 60, at least when the balancing pilot valve 80 is closed.

[0114] exist Figure 12 and Figure 13 The lower part 60b of the piston 60 can be seen best from the center. Figure 13 The lower part 60b is composed of Figure 12 A cross-sectional view in a plane spanned by the central axis C and the transverse axis CT. It includes the flange section 90, where the outer diameter is greater than the piston diameter DP (see [link]). Figure 5 Flange section 90 includes a seal mount 92. A sealing member 94 is received in the seal mount 92 and secured therein by a retaining ring 95 that engages the inward flange 91 at the outlet side of the flange seal mount 92. When valve 1 is closed, the outlet side of the sealing member 94 abuts the valve seat 13. This prevents fluid flow from the inlet pressure chamber 12 to the fluid passage 13a. The fluid passage 93 provides fluid communication between the interior of the seal mount 92 and the inlet pressure chamber 12.

[0115] The opening area of ​​valve seat 13 can correspond to the effective area of ​​piston 60. The inner diameter of valve seat 13 can correspond to piston diameter DP.

[0116] The sealing area at valve seat 13 is defined by the outer circumference of valve seat 13, and in this embodiment by the nozzle sealing diameter DS of valve seat 13. The sealing area includes the contact area between valve seat 13 and piston 60 (especially sealing member 94) when the valve is closed, and the area surrounded by said contact area. In this example, the sealing area is larger than the equilibrium area, for example, by 2% to 20%. For example, the piston diameter DP is 6 mm, and the nozzle sealing diameter DS is 6.3 mm.

[0117] Figure 3 This shows what happens when valve 1 is closed. Figure 1 An enlarged view of section S1 of the indicated valve 1. The equalizing pilot valve 80 is closed. Figure 6 As shown Figure 1 An enlarged view of section S2 of the indicated valve 1. The piston 60 abuts against and seals against the valve seat 13.

[0118] Valve 1 includes a fluid vent 25 extending from the inlet pressure chamber 12 and / or the fluid inlet 11 to the pressure balancing chamber 20. As an example, the fluid vent 25 is formed by a labyrinth seal 26 between the piston 60 and the rod guide passage 3b. The outer peripheral wall of the intermediate portion 62 of the piston 60 is structured, for example, to have helical grooves (see...). Figure 10 The rod guide channel 3b may have an external thread 27 or multiple annular grooves to form a labyrinth seal 26. The sidewalls of the rod guide channel 3b may be (at least substantially) smooth. In a variation, the sidewalls of the rod guide channel 3b are structured, for example, to have helical grooves or multiple annular grooves to form the labyrinth seal 26. In this case, the outer circumferential wall of the intermediate portion 60 may be (at least substantially) smooth, or it may be structured. The labyrinth seal 26 may include at least 25 annular grooves or at least 50 helical rings.

[0119] The fluid vent 25 allows restricted fluid flow from the inlet pressure chamber 12 to the balancing chamber 20. The fluid vent has a first flow resistance (for this fluid flow). When the balancing pilot valve 80 is closed, the pressure in the balancing chamber 20 (balancing pressure) increases towards the inlet pressure in the inlet pressure chamber 12. The resulting high balancing pressure causes a balancing force on the piston 60. This helps to keep valve 1 reliably closed.

[0120] The protrusion 64 has a basic cylindrical shape. However, the protrusion has at least one grooved portion 66, preferably several grooved portions 66. In this embodiment, there are three grooved portions 66, which are evenly arranged around the circumferential direction.

[0121] The outer peripheral walls of the protrusion 64 are tapered in each grooved portion 66 (e.g., inward, in other words, towards the central axis C along the flow direction). Individual grooved portions 66 may correspond to recesses, which can be described by the intersection of an inclined plane with the basic cylindrical shape of the protrusion 64. The resulting shape of the grooved portions 66 and the flow passage reduces the aerodynamic impact on the piston 60 at all opening degrees.

[0122] When the piston 60 is lifted from the valve seat 13, a corresponding flow passage 67 from the inlet pressure chamber 12 through the valve seat 13 to the fluid outlet 15 is formed at each grooved portion 66, specifically between the conical section of the inner circumferential wall of the valve seat 13 and the outer circumferential wall of the protrusion 64. Figure 7 This shows what happens when valve 1 is fully open. Figure 2 Section S2 is shown in the figure, where piston 60 is in the fully retracted position. Figure 8 A further magnified area around the valve seat is shown, in which the piston 60 has been lifted from the valve seat 13 and is in a position between the adjacent position and the fully retracted position.

[0123] To open valve 1, the equalizing pilot valve 80 is first opened. Because the mechanical connection 55 between the drive member 50 and the piston 60 allows for limited relative axial movement of these components, in the initial / first stage of opening valve 1, the piston 60 remains in its abutment position, and only the drive member 50 moves proximally. This opens the equalizing pilot valve 80. The sealing member 53 is lifted from the end 61a, thereby opening the equalizing chamber opening 71. Direct fluid communication between the equalizing passage 70 and the equalizing chamber 20 is established. Because the pressure at the equalizing opening 72 (downstream of valve seat 13) corresponds to the outlet pressure and is, in this case, lower than the equalizing pressure, fluid escapes from the equalizing chamber 20 through the equalizing passage 70 toward the outlet 15 (not directly through the space between the piston 60 and valve seat 13).

[0124] The balancing passage 70 provides a first flow resistance to the fluid. This first flow resistance is less than a second flow resistance, for example, at most half (possibly one-eighth) of the second flow resistance. Because fluid can escape from the balancing chamber 20 through the balancing passage 70 more easily than it can be re-delivered to the balancing chamber 20 when the balancing pilot valve 80 is open, the balancing pressure decreases. Consequently, the balancing force on the piston 60 decreases considerably, for example, to a minimum.

[0125] Once the limited relative axial movement is exhausted (reaching the end), the mechanical coupling 55 drives the piston 60 to follow the drive member 50 in the same direction (here: towards the proximal side) for further axial movement. Figure 4 It shows the relationship with Figure 3 In comparison, the drive member 50 is axially displaced relative to the piston 60. Figure 4 In the middle, the limited relative axial movement has just been used up, and the shoulder 49b has just engaged the first flange 57. The piston 60 is still in the position with Figure 3 In the same position, that is, in its adjacent position. Figure 4 This indicates the end of the first phase of the opening.

[0126] In the second stage of opening, the drive member 50 actuates the piston 60 via the mechanical coupling 55. From this point onward, the piston 60 follows any further proximal movement of the drive member 50 with a corresponding proximal displacement. Due to the pressure compensation achieved by opening the equalizing pilot valve 80 in the first stage, the actuating force required to begin lifting the piston 60 from the valve seat 13 can be determined solely by multiplying the contact area (i.e., the area not surrounding the contact area) by the pressure difference between the inlet and outlet pressures plus friction. The total distal force exerted by the fluid (i.e., the balancing force and other axial forces on the piston 60 generated by the fluid) can act distally and, in this case, has an absolute value less than the upper limit. In this example, the upper limit is 50 N. The upper limit can depend on the valve size.

[0127] Piston 60 begins to lift off valve seat 13 and move away from its adjacent position. Flow passage 67 between valve seat 13 and the grooved portion 66 of protrusion 64 opens and widens as piston 60 moves proximally relative to valve body 10. As long as piston 60 lifts off valve seat 13 only slightly in the second stage (e.g., 0.2 mm to 0.3 mm), the effect of inlet pressure on protrusion 64 remains small.

[0128] The more the piston 60 shifts away from its adjacent position, the larger the "release portion" 64f of the protrusion 64 becomes (see...). Figure 7 The release portion 64f is located upstream of the valve seat 13 in the inlet pressure chamber 12 and is therefore subjected to the inlet pressure.

[0129] The release portion 64f may include a tapered section that narrows toward the outlet side, for example because the protrusion 64 has at least a substantially conical shape and / or because the at least one grooved portion 66 is tapered, as in this example. The inlet pressure at the release portion 64f will apply an additional proximal force to the piston 60 (particularly at the release section of the grooved portion 66). This additional proximal force increases with the displacement of the piston 60 from its adjacent position, potentially until the protrusion 64 is fully retracted into the pressure inlet chamber 12.

[0130] Piston 60 includes a supplemental equalization passage 73 for establishing a fluid connection between inlet pressure chamber 12 and equalization passage 70 when piston 60 is lifted from valve seat 13. Supplemental equalization passage 73 includes a channel opening 74 disposed in the protrusion 64 of piston 60, outside any of the grooved portions 66. At least over a predetermined range of movement MR of piston 60, the effective flow cross-section of supplemental equalization passage 73 (i.e., from inlet pressure chamber 12 to equalization passage 70) gradually increases, for example linearly, with increasing proximal displacement of piston 60.

[0131] In an exemplary embodiment, the supplementary equalization passage 73 has a groove 75 formed in the region of the outer circumference 65 of the protrusion 64, including the channel opening 74. The groove 75 extends along the axial direction L and tapers as the cross-sectional area increases toward the outlet side. Figure 1 , Figure 2 , Figure 6 , Figure 7 , Figure 8 , Figure 11 and Figure 13 In the cross-sectional view, the groove 75 appears as a triangular cutout in the outer circumference of the protrusion 64. The groove 75 and the channel opening 74 are arranged completely on the outside of the grooved portion in the cross-section of the outer circumference 65, which has a generally conical shape.

[0132] Especially when the displacement of piston 60 from its adjacent position is still small, the fluid flow between valve seat 13 and piston 60 is still small, and the pressure around equalization opening 72 is still relatively low, for example (at least) essentially the initial outlet pressure.

[0133] Without supplemental equalization passage 73, the (main) equalization passage 70 will still completely reduce the equalization pressure to the relatively low pressure around the equalization opening 72. The equalization force on piston 60 (generated by the equalization pressure) will increase more slowly with the increase of piston 60 displacement than the additional proximal force on piston 60 generated by the inlet pressure acting on the release portion 64f. This will generate an undesirable total proximal force on piston 60, which may cause unintended proximal movement of piston 60 and thus cause undesirable capacity jumps in valve 1.

[0134] The additional supplemental balancing passage 73 ensures that the balancing pressure rises more rapidly as the piston 60 shifts away from its adjacent position. The supplemental balancing passage 73 is adapted such that the progression of the balancing force on the piston 60, at least within the range of motion MR, is well matched to the progression of the additional proximal force applied to the release portion by the inlet pressure on the piston 60. This allows for smooth opening and closing of valve 1 with a less powerful motor 31. Because the additional proximal force is well compensated, the resilient resetter element 43 can be less forceful. The force generated for operating valve 1 can be reduced in all positions.

[0135] Figure 9The effective flow cross-section (effective cross-section, given in area, for example, EFC) of the supplementary equalization passage 73 is shown relative to the piston 60 without abutment against the valve seat 13 (axial displacement expressed as a percentage of the maximum stroke MS). When the axial displacement is zero, the effective flow cross-section is practically zero (not shown). Within a predetermined movement range MR, the effective flow cross-section increases linearly with increasing axial displacement. Within the predetermined movement range, the overlap of the groove 75 with the inlet pressure chamber 12 determines the effective flow cross-section. This overlap increases with increasing axial displacement. The pressure increase applied via the supplementary equalization passage 73 (to the equalization passage 70 and the balancing pressure) balances the equalization opening 72. The pressure increase of the balancing pressure can occur at the same rate as the inlet pressure affects the protrusion 64 (e.g., its release portion 64f) in the proximal direction.

[0136] If the axial displacement reaches a certain threshold, the effective flow cross-section becomes saturated. Therefore, the effective flow cross-section of the supplementary balancing passage is determined by the flow cross-section of the channel between opening 74 and / or the (main) balancing passage 70 and opening 74. When the piston 60 moves further toward the fully retracted position, the pressure at the balancing opening 72 may no longer increase significantly.

[0137] Valve 1 includes a resetter element 43 for automatically pushing valve 1 toward a predetermined state when motor 31 is not powered. In other words, valve 1 includes a mechanical fail-safe function. In this example, the predetermined state is the closed state. Valve 1 is a normally closed valve. In a variant (not shown), the predetermined state is the fully open state. In this case, the resilient resetter element 43 must be arranged such that its resilient force ultimately pushes piston 60 toward its fully retracted position.

[0138] In valve 1, a reset element 43 is arranged between the flange section 52 of the drive member 50 and the valve body 10. A first end of the reset element 43 is axially abutted against the flange section 52, and a second end is axially abutted against the valve body or at least axially fixed to an element of the valve body. In this example, the second end abuts against a support plate 6a in the motor housing section 6 for supporting the motor shaft 35. The reset element 43 pushes the drive member 50 directly distally (i.e., towards the valve seat 13 along the axial direction L). Once the maximum relative axial movement between the drive member 50 and the piston 60 is exhausted, the drive member 50 (especially the sealing member 53) directly abuts the piston 60 and thereby seals the equalization passage 70, as explained above. Therefore, the piston 60 follows any further distal movement of the drive member 50 relative to the valve body 10 (and thus towards the valve seat 13). The distal movement of the drive member 50 can be caused by the motor 31 and / or the reset element 43.

[0139] The resetter element 43 can be an elastic element, such as a spring. Figure 1 and Figure 2 In the valve 1 shown, the resetter element 43 is an axial spring, such as a cylindrical helical spring. A

[0140] Figure 11 The valve 100 shown according to the second embodiment has substantially the same structure and functionality as the valve 1 according to the first embodiment. The same reference numerals are used for the same elements. Generally, all explanations given regarding valve 1 and its components correspond to valve 100 and its components, and vice versa. Therefore, only the differences are described in more detail.

[0141] The valve 100 according to the second embodiment has three main differences. All the main differences involve the valve actuator 130.

[0142] First, in valve 100, in addition to rotor 133, stator 134 of motor 131 is also housed in motor chamber 132. This makes motor 131 more efficient and facilitates production. However, valve 1 is better suited for use with certain refrigerants as described above. Motor 131 can be a stepper motor, for example, a variable reluctance stepper motor in this embodiment.

[0143] Secondly, the valve actuator 130 of valve 100 is further included in a gearbox 136 between the motor 131 and the valve actuator 130. This allows for the use of a less powerful and therefore smaller, lighter and more efficient motor 131.

[0144] In this example, gearbox 136 includes a plurality of gears 137a, 137b, and 137c. Figure 16 The motor cross-section of valve 100 is shown. The first gear 136a is fixed to the motor shaft 135, at least in a rotational sense. The last gear 136c is fixed, at least in a rotational sense, and possibly axially fixed to the main shaft 40. The last gear 137c is supported by ball bearings 138. Ball bearings 138 are fitted into the intermediate housing section 105. The gear ratio (revolving main shaft 40 / revolving motor shaft 35) is greater than 1:1, for example, 1:0.5 (two rotations of motor shaft 135 result in one rotation of main shaft 40). This facilitates the rewinding of motor 31 via resilient resetter elements 143, 243 in the event of a power failure.

[0145] Third, in valve 100, a torsion spring directly engaged with spindle 40 serves as an elastic resetter element 143, 243. The first end (inner end) 243a of torsion springs 143, 243 is directly fixed to spindle 40. The second end (outer end) 243b, 243b of torsion springs 143, 243 is directly fixed to valve body 10 and is prevented from rotating relative to valve body 10. In this example, the second end 143b, 243b engages one of slots 49b.

[0146] exist Figure 11 In the middle, the elastic resetter element 143 is as follows Figure 17 The circular helical torsion spring shown. Alternatively, such as... Figure 18 The flat torsion spring shown can be used as an elastic resetter element 243.

[0147] In a variation of valve 100 (not shown), torsion springs 143, 243 act directly on motor shaft 135 or on any of gears 137a, 137b, 137c. Gearbox 136 may also include additional gears for connecting torsion springs 143, 243 to valve actuator 130.

[0148] In the event of a power failure, the resilient retainer elements 43, 143, and 243 initially displace the drive element 50 distally relative to the piston 60 until the equalizing pilot valve 80 closes. As the equalizing pilot valve 80 closes, the fluid venting increases the balancing pressure. This increased balancing pressure helps push the piston 60 distally into its adjacent position. Further distal movement of the drive element 50 caused by the retainer element 50 ensures that the equalizing pilot valve 80 remains closed and actuates the piston 60. However, the primary driving force for closing the valve is the resilient force of the retainer elements 43, 143, and 243. Valves 1 and 100 will also be able to close without a pressure differential.

[0149] Regarding both valves 1 and 100, the threaded engagement between the spindle 40 and the drive members 50 and 150 can be non-locking. Specifically, the pitch of the threaded engagement between the spindle 40 and the drive members 50 and 150 can be at least 3 mm per revolution, for example, in the range of 3.5 mm to 6 mm per revolution. This ensures that the resistance of the valve actuator 30 to the elastic force of the resetter elements 43, 143, and 243 is small in the event of a power failure. The resetter elements 43, 143, and 143 can be less robust. Accordingly, since the motors 31 and 131 must overcome the smaller elastic force of the resetter elements 43 and 143 to open valves 1 and 100, the motors 31 and 131 can be less powerful and therefore lighter, cheaper, and more efficient. Furthermore, the large pitch allows for a faster transition between the closed and fully open states at the same rotational speed of the motors 31 and 131.

[0150] The anti-rotation mechanism 49 may include at least one spline 49a (e.g., an anti-rotation wing) at one of the drive members 50, 150 and the valve body 10, and a corresponding slot 49b (or groove) at the other of the drive members 50, 150 and the valve body 10, the corresponding slot for guiding the at least one spline 49a along the axial direction L. In the embodiment shown in the figures, the drive members 50, 150 include two splines 49a, which engage with a corresponding axially extending slot 49b formed in the valve body 49 (to...). Figure 5 , Figure 11 , Figure 14 and Figure 15 (Compared). In the valve 1 according to the first embodiment, spline 49a is arranged on the outer circumference of the flange section 52.

[0151] In valves 1 and 100 according to exemplary embodiments, an axially extending slot 49b is formed on the sidewall of the balance chamber 20. The sidewall of the balance chamber 20 corresponds to the portion of the guide inserts 4 and 104 that avoids the inner circumferential wall portion of the balance chamber 20.

[0152] Guide pin 68 may be formed at the distal end of protrusion 64 (see...) Figure 13 The guide pin 68 helps to prevent lateral vibration of the protruding part 64.

[0153] Valves 1 and 100 can be configured such that the total force applied to piston 60 by the fluid always points to the distal side (i.e., toward the adjoining side of valve seat 13) at any opening of valves 1 and 100.

[0154] Figure 19 A flow control valve 300 according to a third embodiment of the present invention is shown. Valve 300 has substantially the same structure and functionality as valves 1 and 100. The same reference numerals are used for the same elements. Generally, the explanations given with respect to valves 1 and 100 and their components apply correspondingly to valve 300. Only the differences are described below.

[0155] Valve 300 includes a reset mechanism with two resilient reset elements 343a and 343b, which automatically bring piston 60 to a predetermined state when motor 31 is not powered. In this embodiment, the predetermined state is neither a closed state nor a fully open state, but a partially open state of valve 300. In other words, in the predetermined state, valve 300 has a predetermined opening degree less than the maximum opening degree. Figure 19 The diagram shows valve 300 in a predetermined state, in which piston 60 is in a predetermined position, displaced a predetermined distance PD without abutting valve seat 13 (i.e., away from its adjacent position). The predetermined distance is less than the adjacent position of piston rod 60 compared to its fully retracted position. Figure 19 Not shown in the diagram, but related to valve 1Figure 5 The maximum stroke MS is shown in the figure.

[0156] In this embodiment, the drive member 350 additionally includes a washer flange 346 at its outer circumference. Furthermore, the drive member 350 corresponds to... Figure 1 The driving component 50 in it has the same functionality.

[0157] The reset mechanism includes a washer flange 346, a first elastic reset element 343a, a first washer 344a, a second elastic reset element 343b, a second washer 344b, and a stop 307. Both elastic reset elements 343a and 343b are axial springs, more specifically, cylindrical helical springs.

[0158] A first resilient reset element 343a is disposed between a first washer 344a and a support plate 6a. A second resilient reset element 343b is disposed between a second washer 344b and a spring cup 308. The spring cup 308 is fixed relative to the valve body 10 (at least axially), for example, to the intermediate housing section 5. Furthermore, a stop 307 is fixed relative to the valve body 10 (at least axially), for example, also to the intermediate housing section 5.

[0159] The first washer 344a and the second washer 344b are axially movable relative to the valve body 10. A stop 307 restricts the axial movement of the first washer 344a and the second washer 344b. Specifically, the stop restricts the distal axial movement of the first washer 344a relative to the valve body 10 and the proximal axial movement of the second washer 344b relative to the valve body.

[0160] When valve 300 Figure 19 When the piston 60 is in a predetermined state, the first spring 343a pushes the first washer 344a to abut against the washer flange 346 (motor side) and the stop 307. Simultaneously, the second spring 343b pushes the second washer 344 to abut against the washer flange 346 (piston side) and the stop 307. For example, the stop 307 may be an inward flange or a protrusion. Accordingly, the piston 60 is held in its predetermined position at a predetermined distance PD from the abutment on the valve seat 13. The groove 75 partially opens into the inlet pressure chamber 12.

[0161] When the valve actuator 30 (with motor 31) moves the drive member 350 proximally relative to a predetermined state (i.e., as...), Figure 20 As shown, in Figure 19When the valve moves upward, the washer flange 346 displaces the first washer 344a, disengaging it from the stop 307 and moving it proximally away from the stop. The first resilient reset element 343a is further compressed. Once the motor 31 is no longer powered, the elastic force of the first resilient reset element 343a pushes the first washer 344a distally back into contact with the stop 307. Thus, it pushes the valve 300 back to its predetermined state. As long as the washer flange 346 is separated from the second washer 344b, the second resilient member 343b will not affect the drive member 350.

[0162] When the valve actuator 30 (with motor 31) moves the drive member 350 to the distal side relative to a predetermined state (i.e., as... Figure 21 As shown, in Figure 19 When the valve moves downward, the washer flange 346 displaces the second washer 344b, disengaging it from the stop 307 and displacing it distally away from the stop. The second resilient reset element 343b is further compressed. When the motor 31 is no longer powered, the elastic force of the second resilient reset element 343b pushes the second washer 344b proximally back into contact with the stop 307. Thus, it pushes the valve 300 back to its predetermined state. As long as the washer flange 346 is separated from the first washer 344a, the first resilient member 343a will not affect the drive member 350.

[0163] List of reference numerals in the attached diagram:

[0164] 1; 100 valve

[0165] 2 Lower shell section

[0166] 3-seat insert

[0167] 3a downstream sidewall

[0168] 3b rod guide channel

[0169] 4; 104 guide insert

[0170] 5; 105 Intermediate Shell Section

[0171] 6; 106 Motor housing section

[0172] 6a support plate

[0173] 10 Valve Body

[0174] 11 (fluid) inlet

[0175] 11a Entry Port

[0176] 12 Inlet Pressure Chamber

[0177] 13 valve seat

[0178] 13a fluid pathway

[0179] 14 Outlet Pressure Chamber

[0180] 15 (Fluid) Outlet

[0181] 15a Export Port

[0182] 20 balance chambers

[0183] 25 Fluid Discharge Section

[0184] 26 Labyrinth Seals

[0185] 27 External Thread

[0186] 30; 130 valve actuator

[0187] 31; 131 motor

[0188] 32; 132 (motor) chamber

[0189] 33; 133 rotor

[0190] 34; 134 stator

[0191] 35 and 135 motor shafts

[0192] 40 spindle

[0193] 41 External Thread

[0194] 43; 143; 243 Resetter Components

[0195] 45 Conversion Mechanism

[0196] 49 Anti-rotation mechanism

[0197] 49a spline

[0198] 49b (axial) slot

[0199] 50; 150; 350 drive components

[0200] 51 internal thread

[0201] 52 Flange Section

[0202] 53 Sealing components

[0203] 53a sealing component installation parts

[0204] 53b Annular Groove

[0205] 53c retaining ring

[0206] 54-hook structure

[0207] 54a receiving recess

[0208] 54b shoulder

[0209] 55 Mechanical Connectors

[0210] 57 First flange

[0211] 58 grooves

[0212] 59 Second flange

[0213] 60 piston

[0214] 60a (piston) main rod

[0215] 60b (piston) lower part

[0216] 60c threaded joint

[0217] 61 Driver-side end portion

[0218] 61a end

[0219] 62 Middle Part

[0220] 64 protrusions

[0221] 65 (outer) circumference

[0222] 66 slotted section

[0223] 67 flow pathways

[0224] 68 Guide Sales

[0225] 70 Balanced Pathways

[0226] 71 Balance Chamber Opening

[0227] 72 Equal Opening

[0228] 73 Supplemental Balanced Pathways

[0229] 74-channel opening

[0230] 75 groove

[0231] 80 Equalization Pilot Valve

[0232] 90 flange section

[0233] 91 Inward flange

[0234] 92 Sealing Installation Part

[0235] 93 fluid pathways

[0236] 94 Sealing Components

[0237] 95 retaining ring

[0238] 136 Gearbox

[0239] 137a (First) Gear

[0240] 137b gear

[0241] 137c (Final) Gear

[0242] 138 ball bearing

[0243] 143a; 243a First end (inner end)

[0244] 243b; 243b second end (outer end)

[0245] 307 stop parts

[0246] 308 Spring Cup

[0247] 343a First elastic resetter element

[0248] 343b Second Elastic Reset Element

[0249] 344a First Washer

[0250] 344b Second Washer

[0251] 346 washer flange

[0252] AX (horizontal coordinate) (axial shift)

[0253] C Central Axis

[0254] EFS (Effective Flow Section)

[0255] DP piston diameter

[0256] DS Nozzle Sealing Diameter

[0257] MR travel range

[0258] MS maximum stroke

[0259] PD Pre-shift

[0260] L-axis direction.

Claims

1. A flow control valve (1; 100), for example, an expansion valve for a refrigeration system, the flow control valve being a pressure-balanced piston type and having a mechanical fail-safe function, the valve (1; 100) comprising: The valve body (10) has a fluid inlet (11), an inlet pressure chamber (12) fluidly connected to the fluid inlet (11), a fluid outlet (15), a valve seat (13) disposed between the inlet pressure chamber (12) and the fluid outlet (15), and a balance chamber (20). Piston (60), and A valve actuator (30) is used to control the flow of fluid from the fluid inlet (11) through the valve seat (13) to the fluid outlet (15) by displacing the piston (60) relative to the valve seat (13) in the axial direction (L), wherein, The valve actuator (30) includes a motor (31; 131) and a drive member (50; 150; 350), which can be driven by the motor (31; 131) to axially drive the piston (60). The piston (60) protrudes into the balancing chamber (20) with its actuator-side end portion (61), and includes a balancing passage (70) from the actuator-side end portion (61) to a balancing opening (72) fluidly connected to the fluid outlet (15), the balancing passage having a first flow resistance. The valve (1; 100) includes a fluid discharge section (25) from the inlet pressure chamber (12) and / or the fluid inlet (11) to the balance chamber (20), wherein the fluid discharge section (25) is separate from the balancing passage (70) and has a second flow resistance greater than the first flow resistance, and The valve (1; 100) includes a balance pilot valve (80) for opening and closing the balance passage (70).

2. The valve (1; 100) according to claim 1, wherein, The motor (31; 131) is a stepper motor, and the valve driver (30) includes a conversion mechanism (45) for converting the rotational movement provided by the stepper motor (31; 131) into axial movement of the piston (60).

3. The valve (1; 100) according to claim 2, wherein, The motor (31; 131) is a variable reluctance stepper motor.

4. The valve (1; 100) according to any one of the preceding claims, wherein, At least one rotor (33; 133) of the motor (31; 131) is housed in a motor chamber (32; 132) that is fluidly connected to the balancing chamber (20).

5. The valve (1; 100) according to any one of the preceding claims, wherein, The drive member (50; 150; 350) and the piston (60) form the equalization pilot valve (80), wherein the mechanical coupling (55) between the drive member (50; 150; 350) and the piston (60) allows the drive member (50; 150; 350) to make limited relative axial displacement relative to the piston (60) for opening and closing the equalization pilot valve (80).

6. The valve (1; 100) according to any one of the preceding claims, wherein, The valve (1; 100) includes a labyrinth seal (26) between the piston (60) and the valve body (10) at the intermediate portion (62) between the inlet pressure chamber (12) and the balance chamber (20), wherein the labyrinth seal (26) forms part of the fluid venting section (25).

7. The valve (1; 100) according to any one of the preceding claims, wherein, The valve (1; 100) includes resilient reset elements (43; 143; 343a, 343b) for automatically bringing the piston (60) to a predetermined position when the motor (31) is not powered.

8. The valve (1; 100) according to any one of the preceding claims, wherein, The drive member (50; 150; 350) is threadedly engaged with and driven by the spindle (40), which is rotatable by the motor (31; 131), wherein the pitch (42) of the threaded engagement between the drive member (50; 150; 350) and the spindle (40) is at least 3 mm per revolution.

9. The valve (100) according to claims 7 and 8, wherein, The elastic reset element (143) is a torsion spring and acts directly on the main shaft (40).

10. The valve (1; 100) according to any one of the preceding claims, wherein, The equalizing pilot valve (80) opens before the piston (60) is lifted from the valve seat (13) to open the valve (1; 100).

11. The valve (1; 100) according to any one of the preceding claims, wherein, The piston (60) includes a protruding portion (64) at the outlet end opposite to the actuator-side end portion (61) in the axial direction (L). The protruding portion has an outer circumference (65) corresponding to the inner circumference of the valve seat (13). The protruding portion (64) has at least one grooved portion (66). When the piston (60) is lifted from the valve seat (13), a flow passage (67) from the inlet pressure chamber (12) through the valve seat (13) to the fluid outlet (15) is defined between the at least one grooved portion (66) and the valve seat (13).

12. The valve (1; 100) according to claim 11, wherein, The piston (60) includes a supplemental equalization passage (73) for establishing a fluid connection between the inlet pressure chamber (12) and the equalization passage (70) when the piston (60) is removed from the valve seat (13), wherein the supplemental equalization passage (73) includes a channel opening (74) disposed in the protrusion (64) of the piston (60) on the outside of any of the grooved portions (66).

13. The valve (1; 100) according to claim 12, wherein, Within a predetermined range (MR) of movement of the piston (60) along the axial direction (L), the effective flow cross section (76) of the supplementary equalization passage (73) gradually increases as the piston (60) moves axially toward the drive end side.

14. The valve (1; 100) according to claim 12 or 13, wherein, The supplemental equalization passage (73) has a groove (75) formed in the region of the outer circumference (65) of the protrusion (64) including the channel opening (74), wherein the groove (75) extends along the axial direction (L) and tapers as the cross-sectional area increases toward the outlet side.

15. The valve (1; 100) according to any one of the preceding claims, wherein, The valve actuator (30) includes a gearbox (136) between the motor (131) and the drive member (150).

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