Biasing device

Abstract

A biasing device for biasing a biasing member with a predetermined force is provided. The biasing device comprises an actuation means, a pressure transducing means, an elastic member, and the biasing member. The pressure transducing means comprises a first cylinder including a first piston configured to reciprocate within the first cylinder in a working direction of the first cylinder, and a second cylinder including a second piston configured to reciprocate within the second cylinder in a working direction of the second cylinder. An interior of the first cylinder communicates with the interior of the second cylinder via a communication path. The actuation means is configured to reciprocate the first piston in the working direction of the first cylinder upon operation, and the elastic member is interposed between the biasing member and the second piston so as to exert an urging force to the biasing member and to the second piston in a compressed state.

Description

[0001] DESCRIPTION

[0002] Title of the invention

[0003] Biasing device

[0004] Technical field to which the invention relates

[0005] The present invention relates to a biasing device, and in particular, to a biasing device for biasing a biasing member with a predetermined force. In addition, the present invention relates to a pressure regulator comprising the biasing device.

[0006] Indication of background art

[0007] In, for example, a hydrogen dispenser of a hydrogen refuelling station, a pressure regulator is used to adjust the refuelling pressure during the refuelling process according to certain specifications. Such pressure regulators are typically called ramp regulators and are conventionally pneumatically driven.

[0008] By using the pressure regulator, an outlet pressure of the pressure regulator can be adjusted to a specific value regardless to an (higher) inlet pressure supplied to the pressure regulator. In the conventional pressure regulator, a pre-loaded spring is provided for biasing a valve disc with a predetermined force. The valve disc cooperates with a valve seat to selectively allow an inlet port to communicate with an outlet port of the pressure regulator. The biasing force of the spring is in balance with a force applied to a sensor piston and generated by the current outlet pressure acting on a pressure-effective surface area of the sensor piston. If the outlet pressure decreases (e.g., when the refuelling process starts or a fluid consumption of the downstream consumers increases), the resulting pressure force on the senor piston decreases and the pre-loaded spring elongates. The resulting axial movement is transmitted to the valve disc, which thereby lifts off the valve seat and allows fluid to flow from the inlet port to the outlet port of the pressure regulator until the resulting pressure force acting on the sensor piston increases such that the spring is compressed and the valve disc returns to its initial position closing the valve seat. The pre-load of the spring is conventionally implemented by an air transducer operated with compressed air.

[0009] Pneumatic components provide simple solutions that are well known and easy to use. However, the pneumatic components used in the hydrogen dispenser require costly recurring maintenance resulting in long downtimes during which the station cannot be used. As a result, more and more components have recently been replaced by electrically driven or controlled components.

[0010] However, until now it has not been possible to replace the pneumatically driven pressure regulators with corresponding electrically driven components.

[0011] Therefore, it is still necessary to provide the infrastructure for the supply of compressed air within the hydrogen refuelling station, with the associated drawbacks.

[0012] Therefore, there is a need for a biasing device whose operation involves less maintenance and, consequently, less costs.

[0013] Technical problem to be solved

[0014] In view of the above, it is the object of the present invention to provide a biasing device capable of reducing maintenance and associated costs.

[0015] Disclosure of the invention

[0016] The object is achieved by a biasing device having the features of independent claim 1. A pressure regulator comprising the biasing device according to the invention is subject-matter of claim 15. Further advantageous developments are set out in the dependent claims.

[0017] According to the invention a biasing device for biasing a biasing member with a predetermined force comprises an actuation means, a pressure transducing means, an elastic member, and the biasing member. The pressure transducing comprises a first cylinder including a first piston configured to reciprocate within the first cylinder in a working direction of the first cylinder and a second cylinder including a second piston configured to reciprocate within the second cylinder in a working direction of the second cylinder. An interior of the first cylinder communicates with the interior of the second cylinder via a communication path. The actuation means is configured to reciprocate the first piston in the working direction of the first cylinder upon operation. The elastic member is interposed between the biasing member and the second piston so as to exert an urging force to the biasing member and to the second piston in a compressed state.

[0018] The biasing force applied to the biasing member can be adjusted by operation of the actuation means reciprocating the first piston within the first cylinder. By providing the pressure transducing means including the first and second cylinders communicating with each other via the communication path, a desired transmission ratio between the force applied to the first piston and the force applied to the second piston can be implemented. Thus, by appropriately designing the pressure transducing means, the biasing force required by the biasing member can be achieved almost independently of the force provided by the actuation means. This allows a high degree of flexibility in the selection of the appropriate actuation means, and particularly low-maintenance actuation means can be used, reducing the maintenance of the overall system in which the biasing device is used.

[0019] The interior of the first cylinder, the interior of the second cylinder, and the interior of the communication path may form a fluid-tight space filled with a fluid. As a result, a movement of the first piston in the working direction of the first cylinder directly results in a variation of a force generated by the pressure of the fluid and applied to the second piston in the working direction of the second cylinder.

[0020] The fluid may be an incompressible fluid. Consequently, a movement of the first piston in the working direction of the first cylinder directly results in a movement of the second piston in the working direction of the second cylinder. Thus, a rigid coupling is established between the first piston and the second piston.

[0021] A pressure-effective surface area of the first piston in a plane perpendicular to the working direction of the first cylinder may be smaller than a pressureeffective surface area of the second piston in a plane perpendicular to the working direction of the second cylinder. Thus, the force applied to the first piston by the actuation means is amplified by the pressure transducing means and the amplified force is applied to the biasing member via the second piston and the elastic member. As a result, also actuation means can be used that provides less force than is required for biasing the biasing member.

[0022] The working direction of the first cylinder may be inclined to the working direction of the second cylinder. Accordingly, the dimensions of the biasing device can be adapted to the intended use and the available installation space.

[0023] The working direction of the first cylinder may be perpendicular to the working direction of the second cylinder. This allows a short design of the biasing device with respect to the effective direction of the biasing force.

[0024] The working direction of the first cylinder may coincide with the working direction of the second cylinder. This allows a slim design of the biasing device.

[0025] The first cylinder may be at least partially formed inside the second cylinder such that the second cylinder circumferentially surrounds the first cylinder. The elastic member may be formed radially outwardly of the first cylinder so as to at least partially circumferentially surround the first cylinder. As a result, a short design of the biasing device with respect to the effective direction of the biasing force is achieved, while still maintaining a relatively slim design of the biasing device.

[0026] The second piston may comprise a recessed central portion recessed towards a working direction of the second cylinder and the first cylinder may be formed within the recessed central portion of the second piston. By providing the second piston with the recessed central portion accommodating the first cylinder a relatively large transmission ratio of the pressure transducing means can be achieved. This is because the entire cross-sectional area of the second cylinder is substantially used as the pressure-effective surface area of the second piston.

[0027] The second piston may comprise a protruding central portion protruding towards the working direction of the second cylinder and the elastic member may be arranged radially outwardly of the protruding central portion so as to at least partially circumferentially surround the protruding central portion of the second piston. The protruding central portion may at least partially include the recessed central portion of the second piston. Therefore, in addition to the short design of the biasing device, excellent guidance of the elastic member can be achieved.

[0028] The actuation means may be an electrically actuated linear actuator comprising an electric motor. The use of an electrically operated actuator therefore eliminates the need for pneumatic components to operate the biasing device.

[0029] This eliminates the need for a compressed air supply infrastructure, resulting in a lower level of maintenance can be achieved for the system using the biasing device.

[0030] The electric motor of the electrically actuated linear actuator may be a stepper motor. Accordingly, the biasing device can achieve excellent characteristics in adjusting the biasing force exerted by the biasing member.

[0031] The electrically actuated linear actuator may comprise a leadscrew coupled to the first piston and configured to reciprocate upon operation of the electric motor. Accordingly, by providing the leadscrew, the rotary motion of the electric motor can be converted into a linear motion to reciprocate the first piston.

[0032] According to the invention, a pressure regulator comprises an inlet port, an outlet port, a pressure adjusting means, and the above-mentioned biasing device. The inlet port is configured to communicate with a pressure source providing a pressurized fluid. The outlet port is configured to supply the pressurized fluid to a working means at a specific pressure level. The pressure adjusting means adjusts the specific pressure level. The biasing member of the biasing device applies a biasing force to the pressure adjusting means corresponding to the specific pressure level.

[0033] The pressure regulator comprises the biasing device for adjusting the specific pressure level of the fluid supplied by outlet port. The biasing device is operated by the actuation means having a high degree of flexibility in the selection of the appropriate operating energy. As a result, an appropriate actuation means can be selected to operate the biasing device and the pressure regulator, respectively, to achieve a reduced maintenance of the overall system using the pressure regulator. Accordingly, the maintenance of the overall system and the costs associated with it can be kept to a minimum.

[0034] Further benefits and advantages of the present invention will become apparent from the following detailed description of at least one exemplary embodiment for carrying out the present invention with reference to the accompanying drawings.

[0035] Brief description of drawings

[0036] In the drawings:

[0037] Figure 1 is a schematic sectional view of a biasing device according to a first embodiment of the present invention.

[0038] Figure 2 is a schematic sectional view of a biasing device according to a second embodiment of the present invention.

[0039] Description of at least one way of carrying out the invention

[0040] First embodiment

[0041] A first embodiment of the present invention is described below with reference to figure 1.

[0042] Figure 1 illustrates a schematic sectional view of a biasing device 1 according to the first embodiment of the present invention. Figure 1 exemplifies a pressure regulator 200 for the use of the biasing device 1. However, the use of the biasing device according to the present invention is not limited to pressure regulators. Rather, the biasing device 1 can be used in various fields where the application of a specific biasing force is required.

[0043] In the following, the structure of the biasing device 1 according to the first embodiment is described in detail.

[0044] As illustrated in figure 1, the biasing device 1 serves for actuation of the pressure regulator 200. The biasing device 1 comprises a housing 2 accommodating a first cylinder 10 and a second cylinder 20. The first cylinder 10 extends in a first axial direction Al corresponding to a working direction of the first cylinder 10. The second cylinder 20 extends in a second axial direction A2 corresponding to a working direction of the second cylinder 20. According to the first embodiment, the first cylinder 10 is arranged coaxially with the second cylinder 20 so that the first axial direction Al coincides with the second axial direction A2. The first and second axial directions Al, A2 thus correspond to an axial direction A of the housing 2. However, the present invention is not limited thereto. According to the invention, the first and second cylinders 10, 20 may be arranged non- coaxially such that the first axial direction Al is offset with respect to the second axial direction A2. In addition, the first and second cylinders 10, 20 may be arranged such that the first axial direction Al and the second axial direction A2 are angled at any suitable angle to each other, depending, for example, on what the installation situation requires.

[0045] The first cylinder 10 accommodates a first piston 11. The first piston 11 is slidably arranged in the first cylinder 10 so as to be able to reciprocate in the first axial direction Al, i.e., the working direction of the first cylinder 10. The first piston 11 delimits the interior (a working space) of the first cylinder 10 in a fluid- tight manner with respect to the first axial direction Al. The first piston 11 comprises a pressure effective surface SI, which substantially corresponds to the cross-sectional area of the first cylinder. The first piston 11 is coupled to an electrically actuated linear actuator 60. The linear actuator 60 comprises an electric stepper motor 61 and a leadscrew 62. One end of the leadscrew 62 in the first axial direction Al is coupled to the first piston 11. Upon operation of the stepper motor 61, the leadscrew 62 is reciprocated and, therefore, the first piston 11 reciprocates integrally with the leadscrew 62 in the first axial direction Al.

[0046] According to the first embodiment, the first cylinder 10 and the second cylinder 20 are designed one inside the other. That is, the first cylinder 10 is formed inside the second cylinder 20 such that the second cylinder 20 circumferentially surrounds the first cylinder 10. In other words, the first cylinder 10 protrudes into the interior of the second cylinder 20.

[0047] The second cylinder 20 accommodates a second piston 21. The second piston 21 is slidably arranged in the second cylinder 20 so as to be able to reciprocate in the second axial direction A2, i.e., the working direction of the second cylinder 20. The second piston 21 delimits the interior (a working space) of the second cylinder 20 in a fluid-tight manner with respect to the second axial direction A2.

[0048] The second piston 21 includes a recessed central portion 22 recessed towards the second axial direction A2. In particular, the recessed central portion 22 is recessed from a surface of the second piston 21 facing the interior of the second cylinder 20 towards a side opposite to the interior of the second cylinder 20. The recessed central portion 22 at least partially accommodates the first cylinder 10.

[0049] Furthermore, the second piston 21 includes a protruding central portion 23 protruding towards the second axial direction A2. In particular, the recessed central portion 22 protrudes from a surface of the second piston 21 opposite to the interior of the second cylinder 20. The protruding central portion 23 at least partially includes the recessed central portion 22.

[0050] The second piston 21 comprises a pressure effective surface S2, which substantially corresponds to the cross-sectional area of the second cylinder 20. The pressure effective surface S2 of the second piston 21 is larger than the pressure effective surface SI of the first piston 11.

[0051] The interior of the first cylinder 10 communicates with the interior of the second cylinder 20 via a communication path 30. The interior of the first cylinder 10, the interior of the second cylinder 20, and the communication path 30 form a fluid- tight space. This fluid-tight space is filled, for example, with a suitable incompressible working fluid. It should be noted that the term "incompressible fluid" refers to fluids with a bulk modulus K > 0,1 GPa. In the present embodiment, for example, common hydraulic oils can be used as the working fluid. A fluid pressure P in the fluid-tight space corresponds to a fluid pressure Pl in the first cylinder 10 and a fluid pressure P2 in the second cylinder 20 (P = Pl = P2). When using an incompressible working fluid, a movement of the first piston 11 results in a movement of the second piston 21.

[0052] The first cylinder 10 including the first piston 11, the second cylinder 20 including the second piston 21, and the communication path 30 allowing the first cylinder 10 to communicate with the second cylinder 20 form a pressure transducing means. In the present embodiment, the pressure-effective surface area SI of the first piston 11 exposed to the fluid pressure Pl in the first cylinder 10 (i.e., a projected surface area SI of a surface of the first piston 11 exposed to the fluid pressure Pl projected onto a plane perpendicular to the first axial direction Al) is smaller than a pressure-effective surface area S2 of the second piston 21 exposed to the fluid pressure P2 in the second cylinder 20 (i.e., a projected surface area S2 of a surface of the second piston 21 exposed to the fluid pressure P2 projected onto a plane perpendicular to the second axial direction A2). This results in force amplification as the fluid pressure P (= Pl = P2) acts on surface areas SI, S2 of different sizes. A force F2 exerted on the second piston 21 generated by the fluid pressure P is larger than a force Fl exerted on the first piston 11 generated by the fluid pressure P. Thus, according to the present embodiment, the pressure transducing means can also be referred to as a force intensifier. Basically, the pressure transducing means functions as a hydraulic transmission. That is, a relatively large deflection of the first piston 11 in the first axial direction Al caused by a relatively small force results in a relatively small deflection of the second piston 21 in the second axial direction A2 accompanied by a relatively large force applied to the second piston 21.

[0053] The housing 2 of the biasing device 1 further accommodates a biasing member 50. The biasing member 50 is disposed spaced apart from the second piston 21 in the second axial direction A2. In particular, the biasing member 50 is arranged on a side of the second piston 21 opposite to the side exposed to the fluid in the second cylinder 20. The biasing member 50 is substantially formed in a disc-like shape. An axial direction of the biasing member 50 coincides with the second axial direction. However, the design of the biasing member 50 is not particularly limited and can be designed appropriately, e.g., depending on the intended use and the respective installation situation. The biasing member 50 is accommodated in the housing 2 so as to be slidable in the axial direction A (in particular, the second axial direction A2).

[0054] A coil spring 40 constituting an elastic member is axially interposed between the biasing member 50 and the second piston 21. Thus, a movement of the second piston 21 in the second axial direction A2 is transmitted via the coil spring 40 to the biasing member 50. If movement of the biasing member 50 in the second axial direction A2 is restricted and the second piston 21 is moved towards the biasing member 50, the coil spring 40 is compressed and exerts an urging force to the biasing member 50 and to the second piston 21 due to the elastic restoring force of the coil spring 40. In a similar way, if movement of the second piston 21 is restricted and the biasing member 50 is moved towards the second piston 21, the coil spring 40 is compressed and exerts an urging force to the biasing member 50 and to the second piston 21 due to the elastic restoring force of the coil spring 40.

[0055] According to the first embodiment, the coil spring 40 is arranged radially outwardly of the protruding central portion 23 of the second piston 21 so as to circumferentially surround the protruding central portion 23 of the second piston 21 and the first cylinder 10 accommodated in the recessed central portion 22 of the second piston 21. As a result, the first cylinder 10, the second cylinder 20, and the coil spring 40 are arranged in a radially overlapping manner. By this structure, the required installation space for the biasing device 1 can be kept small.

[0056] In the present embodiment the coil spring 40 has been exemplified as an elastic member. However, the present invention is not limited thereto. Also, any other suitable elastic members may be used, for example, a disc spring, a plurality of disc springs arranged in series, a rubber member, etc.

[0057] In the following, the use of the biasing device 1 according to the above embodiment as an actuation unit of the pressure regulator 200 is described in detail with reference to figure 1.

[0058] The pressure regulator 200 comprises an inlet port 201 and an outlet port 202. The inlet port 201 is configured to communicate with, for example, a fuel supply source that supplies fuel, such as hydrogen, at a relatively high pressure. The outlet port 202 is configured to communicate with, for example, a fuel consumer which is supplied with fuel or is refuelling fuel. The pressure at which the fuel is discharged at the outlet port 202 can be adjusted with the pressure regulator 200. Consequently, a pressure at the outlet port side of the pressure regulator 200 can be set to a lower pressure than the pressure at the inlet port side of the pressure regulator 200.

[0059] Therefore, the pressure regulator 200 comprises a valve seat 203 and a valve disc 204 movable in an axial direction A3 of the pressure regulator 200 for selectively opening and closing the valve seat 203. According to the first embodiment, the axial direction A3 of the pressure regulator 200 coincides with the first and second axial directions Al, A2. The valve seat 203 is provided in a communication path between the inlet port 201 and the outlet port 202. Thus, by opening and closing the valve seat 203, the inlet port 201 can be selectively allowed or prevented to communicate with the outlet port 202.

[0060] The valve disc 204 is coupled to a sensor piston 205 having a pressure-effective surface area S3. According to the first embodiment, the sensor piston 205 is integrally formed with the biasing member 50 of the biasing device 1. However, the present invention is not limited thereto. The sensor piston 205 and the biasing member 50 may be formed as separate members.

[0061] The sensor piston 205 constitutes a pressure level adjusting means of the pressure regulator 200. The surface area S3 of the sensor piston 205 is exposed to the pressure at the outlet port side of the pressure regulator 200. The sensor piston 205 is integrally movable with the valve disc 204 in the axial direction. The pressure at the outlet port side of the pressure regulator 200 urges the sensor piston 205 in the axial direction A3 (in an upward direction in figure 1) so as to urge the valve disc 204 coupled to the sensor piston 205 in a position closing the valve seat 203.

[0062] The biasing device 1 is attached to the pressure regulator so that the second axial direction A2 of the second cylinder 20 coincides with the axial direction A3 of the pressure regulator and the biasing member 50 contacts the sensor piston 205.

[0063] When the first piston 11 is moved by actuation of the linear actuator 60 (e.g., by supplying electric power to the stepper motor 61) towards the interior of the first cylinder 10, the second piston 21 is moved towards the biasing member 50. Accordingly, the sensor piston 205 contacting the biasing member 50 is moved together with the valve disc 204 in the axial direction A3 until the valve disc 204 reaches a fully open position. When the fully open position of the valve disc 204 is reached, the movement of the sensor piston 205 and the biasing member 50 towards the valve seat 203 is restricted. Thus, when the first piston 11 is further moved towards the interior of the first cylinder 10, the coil spring 40 interposed between the second piston 21 and the biasing member is compressed. As a result, the coil spring 40 exerts a biasing force to the sensor piston 205 via the biasing member 50 generated by the elastic restoring force of the coil spring 40. The biasing force corresponds to a degree of compression of the coil spring 40. The compression of the coil spring 40 is dependent on the extent of the movement of the second piston 21 toward the biasing member. Since fluid filled in the fluid-tight space formed by the first cylinder 10, second cylinder 20, and the communication path 30 is substantially incompressible, the extent of movement of the second piston 21 corresponds to the extent of movement of the first piston 11. Therefore, the biasing force applied to the sensor piston 205 by the biasing member 50 can be adjusted by reciprocating the first piston 11 in the first cylinder 10.

[0064] When the force applied to the sensor piston 205, which is generated by the outlet port side pressure and is directed in a opposite direction as the biasing force applied to the sensor piston 205 by the biasing member 50, is smaller than the biasing force, the valve disc is maintained in the open position and the inlet port 201 is allowed to communicate with the outlet port 202. When the pressure at the outlet port side exceeds a specific pressure, which is defined by the biasing force and the pressure-effective surface of the sensor piston 205, the force applied to the sensor piston 205 due to the pressure at the outlet port side exceeds the biasing force. Thus, the sensor piston 205 is moved towards the second piston 21 against the biasing force thereby further compressing the coil spring. At the same time, the valve disc 204, which moves integrally with the sensor piston 205, is moved from the open position to a closed position so as to close the valve seat 203. Therefore, the inlet port 201 is prevented from communicating with the outlet port 202 until the outlet port side pressure falls below the specific pressure and the biasing force urges the valve disc 204 together with the sensor piston 205 back to the open position.

[0065] Second embodiment

[0066] A second embodiment of the present invention is described below with reference to figure 2.

[0067] The second embodiment differs from the first embodiment in that the first axial direction Al of the first cylinder 10 does not coincide with the second axial direction A2 of the second cylinder 20. According to the second embodiment, the first axial direction Al of the first cylinder 10 is perpendicular to the second axial direction A2 of the second cylinder 20. 440 Additionally, according to the second embodiment, the second piston 21 does not include a recessed central portion and a protruding central portion and the first cylinder 10 and the second cylinder 20 are designed separate rather than one inside the other.

[0068] 445 According to the second embodiment, although the structure of the biasing device is kept simple, a relatively short design of the biasing device 1 can be realized by arranging the first cylinder 10 perpendicularly to the second cylinder 20. 450 Further modifications of the embodiments

[0069] In the first embodiment, the biasing device 1 is exemplified by the first cylinder 10 and the second cylinder 20 being arranged coaxially one inside the other. However, the present invention is not limited thereto. By appropriate design of 455 the communication path 30, the first and second cylinders 10, 20 may be arranged independently of each other, for example, coaxially one above the other, parallel side by side, or angled at any suitable angle to each other.

[0070] In the first and second embodiments, the first and second cylinders 10, 20 are 460 accommodated in the same housing 2. However, the first cylinder and the second cylinder may be accommodated in separate housings.

[0071] The above-described embodiments of the present invention can be appropriately modified or combined. The above description is not exhaustive, and the present

[0072] 465 invention is not limited to the above embodiments. The skilled person will recognize that various modifications and combinations of the features included in the above embodiments are possible within the scope of the invention. Accordingly, the scope of the invention should be determined from the accompanying claims.

[0073] 470

[0074] Reference sign list

[0075] 1 biasing device 2 housing

[0076] 10 first cylinder

[0077] 11 first piston

[0078] 20 second cylinder

[0079] 21 second piston

[0080] 22 recessed central portion

[0081] 23 protruding central portion

[0082] 30 communication path

[0083] 40 coil spring (elastic member)

[0084] 50 biasing member

[0085] 60 linear actuator (actuation means)

[0086] 61 electric motor

[0087] 62 leadscrew

[0088] 200 pressure regulator

[0089] 201 inlet port

[0090] 202 outlet port

[0091] 203 valve seat

[0092] 204 valve disc

[0093] 205 sensor piston

[0094] 51 pressure-effective surface area (first piston)

[0095] 52 pressure-effective surface area (second piston)

[0096] 53 pressure-effective surface area (sensor piston)

Claims

CLAIMS1. Biasing device (1) for biasing a biasing member (50) with a predetermined force, comprising an actuation means (60), a pressure transducing means, an elastic member (40), and the biasing member (50), the pressure transducing means comprising a first cylinder (10) including a first piston (11) configured to reciprocate within the first cylinder (10) in a working direction (Al) of the first cylinder (10), a second cylinder (20) including a second piston (21) configured to reciprocate within the second cylinder (20) in a working direction (A2) of the second cylinder (20), wherein an interior of the first cylinder (10) communicates with the interior of the second cylinder (20) via a communication path (30), the actuation means (60) is configured to reciprocate the first piston (11) in the working direction (Al) of the first cylinder (10) upon operation, and the elastic member (40) is interposed between the biasing member (50) and the second piston (21) so as to exert an urging force to the biasing member (50) and to the second piston (21) in a compressed state.

2. Biasing device (1) according to claim 1, wherein the interior of the first cylinder (10), the interior of the second cylinder (20), and the interior of the communication path (30) form a fluid-tight space filled with a fluid.

3. Biasing device (1) according to claim 2, wherein the fluid is an incompressible fluid.

4. Biasing device (1) according to any one of claims 1 to 3, whereina pressure-effective surface area (SI) of the first piston (11) in a plane perpendicular to the working direction (Al) of the first cylinder (10) is smaller than a surface area (S2) of the second piston (21) in a plane perpendicular to the working direction (A2) of the second cylinder (20).

5. Biasing device (1) according to any one of claims 1 to 4, wherein the working direction (Al) of the first cylinder (10) coincides with the working direction (A2) of the second cylinder (20).

6. Biasing device (1) according to any one of claims 1 to 4, wherein the working direction (Al) of the first cylinder (10) is inclined to the working direction (A2) of the second cylinder (20).

7. Biasing device (1) according to claim 6, wherein the working direction (Al) of the fist cylinder (10) is perpendicular to the working direction (A2) of the second cylinder (20).

8. Biasing device (1) according to any one of claims 1 to 5, wherein the first cylinder (10) is at least partially formed inside the second cylinder (20) such that the second cylinder (20) at least partially circumferentially surrounds the first cylinder (10).

9. Biasing device (1) according to claim 8, wherein the elastic member (40) is formed radially outwardly of the first cylinder (10) so as to at least partially circumferentially surround the first cylinder (10).

10. Biasing device (1) according to claims 8 or 9, wherein the second piston (21) comprises a recessed central portion (22) recessed towards a working direction (A2) of the second cylinder (20), the first cylinder (10) is formed within the recessed central portion (22) of the second piston (21).

11. Biasing device (1) according to any one of claims 1 to 10, whereinthe second piston (21) comprises a protruding central portion (23) protruding towards a working direction (A2) of the second cylinder (20), and the elastic member (40) is arranged radially outwardly of the protruding central portion (23) so as to circumferentially surround the protruding central portion (23) of the second piston (21).

12. Biasing device (1) according to claim 11, wherein the protruding central portion (23) of the second piston (21) at least partially includes the recessed central portion (22) of the second piston (21).

13. Biasing device (1) according to any one of claims 1 to 12, wherein the actuation means (60) is an electrically actuated linear actuator comprising an electric motor (61).

14. Biasing device (1) according to claim 13, wherein the electric motor (61) is configured to reciprocate a leadscrew (62) coupled to the first piston (11).

15. Pressure regulator (200), comprising an inlet port (201) configured to be in communication with a pressure source providing a pressurized fluid, an outlet port (202) configured to supply the pressurized fluid to a working means at a specific pressure level, a pressure level adjusting means (205) for adjusting the specific pressure level, and the biasing device (1) according to any one of the preceding claims, wherein the biasing member (50) of the biasing device (1) applies a biasing force to the pressure level adjusting means (205) corresponding to the specific pressure level.

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