Device comprising plurality of tools each having at least one hydraulic chamber for hydraulic fluid

Abstract

The invention relates to a device (1) comprising: a plurality of tools (2), each having at least one hydraulic chamber (6) for hydraulic fluid; and a hydraulic manifold (4) configured for storing pressurized hydraulic fluid and for supplying hydraulic fluid to the plurality of tools (2) wherein each tool (2) comprises a communication duct (7) extending between a hydraulic chamber (6) and the hydraulic manifold (4), the hydraulic chamber (6) having a varying volume during operation of the tools (2). The device (1) is characterized in that each tool (2) comprises a hydraulic buffer unit (8) for preventing the propagation of hydraulic pulsations between the tool (2) and the hydraulic manifold (4) in response to a varying volume of the hydraulic chamber (6), where the hydraulic buffer unit (8) has a buffer chamber (9) having a volume that varies in response to a varying volume of the hydraulic chamber (6).

Description

Technical Field

[0001] The present invention generally relates to an apparatus comprising a plurality of tools, wherein each tool comprises at least one hydraulic chamber having a varying volume during operation of the tool.

[0002] The invention relates in particular to an apparatus comprising a plurality of tools, each tool having at least one hydraulic chamber for hydraulic fluid, and comprising a hydraulic manifold configured for storing pressurized hydraulic fluid and for supplying hydraulic fluid to the plurality of tools, wherein each tool comprises a communication conduit extending between a hydraulic chamber and the hydraulic manifold, the hydraulic chamber having a varying volume during operation of the tool.

[0003] Such an installation consists, for example, of a combustion engine assembly and a machine with a hydraulic drive / tool. Background Art

[0004] The present invention is based on the fact that many known applications / devices in various technical fields utilize hydraulic fluid flow, and the utilization of hydraulic fluid flow is related to the operation of the device, that is, hydraulic fluid flows between different locations in the device in order to cause the device to perform a useful task or in response to the device performing a useful task.

[0005] Thus, many applications / apparatus in various fields of technology utilize internal elements / components that are in motion during operation of the equipment, wherein pressurized hydraulic fluid is used for / in the operation of the equipment. Such applications / apparatus with rapid displacement of internal elements / components often experience undesirable pulsations of the hydraulic fluid that can counteract optimal operation. In certain circumstances, such pulsations can also be detrimental to the equipment. Pulsations in the hydraulic fluid are particularly undesirable in equipment with multiple hydraulically interconnected tools / devices.

[0006] In a camless combustion engine, a pressurized fluid is used to achieve the displacement / opening of one or more gas exchange valves. This means that the camshaft and related equipment used by a conventional combustion engine to open the gas exchange valves to let air in and correspondingly let the exhaust gases out of the combustion chamber have been replaced by a less volume demanding and more controllable system utilizing pneumatic / hydraulic operated actuators. During each cycle of the actuator, pressurized fluid is supplied and discharged, and hydraulic fluid is supplied and returned. Such an engine can run at higher speeds / cycles, for example 6rpm to 8000rpm, and can include eight or more pneumatic / hydraulic interconnected actuators, leading to extreme situations where pulsations in the hydraulic fluid are propagated between the actuators.

[0007] There is a need in the art for a simple and reliable solution for an apparatus having multiple tools which prevents pulsations in the hydraulic fluid from propagating between the tools in a reliable manner.

[0008] Purpose of the Invention

[0009] The present invention aims to obviate the above-mentioned disadvantages and drawbacks of previously known devices and to provide an improved device. A main object of the invention is to provide an improved device of the initially defined type, wherein the operation of each tool does not adversely affect the operation of other tools. Another object of the invention is to provide a device which prevents pulsations in the hydraulic fluid from being adversely propagated between a plurality of tools without adversely affecting the operation of each tool. Another object of the invention is to provide a device which prevents pulsations in the hydraulic fluid from being adversely propagated also when the hydraulic fluid pressure in the hydraulic manifold changes. Summary of the invention

[0010] According to the present invention, at least the primary object is achieved by the initially defined device having the features defined in the independent claim. Preferred embodiments of the invention are further defined in the dependent claims.

[0011] According to the invention, there is provided an apparatus of the initially defined type, characterised in that each tool comprises a hydraulic buffer unit for preventing the propagation of hydraulic pulsations between the tool and the hydraulic manifold in response to a varying volume of a hydraulic chamber, wherein the hydraulic buffer unit has a buffer chamber having a volume that varies in response to the varying volume of the hydraulic chamber.

[0012] The invention is therefore based on the recognition that by associating a local hydraulic buffer unit with each individual tool, the unfavorable propagation of pulsations in the hydraulic fluid in the hydraulic manifold due to the operation of the individual tools is prevented. A central hydraulic buffer located in the hydraulic manifold and serving a plurality of tools will not prevent the unfavorable propagation of pulsations in the hydraulic manifold.

[0013] According to various embodiments of the present invention, the hydraulic buffer unit includes a cylinder accommodating a piston, which separates a buffer chamber and a pressure chamber from each other, wherein the piston can be reciprocated in the cylinder, wherein the pressure chamber accommodates a pressure fluid and a spring, wherein the spring is used to shift the piston toward the buffer chamber so as to reduce the volume of the buffer chamber, and wherein the buffer chamber is connected to a connecting pipe fluid, and pressurized hydraulic fluid is used to shift the piston toward the pressure chamber so as to increase the volume of the buffer chamber.

[0014] According to various embodiments of the invention, the piston is associated with a rest position between two end positions in the cylinder, when the piston is in said rest position, the pressure in the communication duct is equal to the sum of the pressure of the pressure fluid in the pressure chamber of the cylinder and the spring force of the spring. Therefore, when the piston is displaced with the operation of the tool and the local pressure in the communication duct is different from the total pressure in the hydraulic manifold, since the liquid communication with the hydraulic manifold is slower than the volume change of the hydraulic chamber of the tool during operation, the piston will always try to return to the rest position when the tool is not in operation.

[0015] According to various embodiments of the present invention, the pressure in the hydraulic manifold is adjustable, and the pressure level in the hydraulic manifold is adjusted based on the pressure level in the pressure chamber of the cylinder. In this way, the pressure level in the pressure chamber of the cylinder of the hydraulic buffer unit will change in response to changes in the operating state of the equipment, that is, increase or decrease, and the pressure level in the hydraulic manifold will change accordingly to ensure the normal operation of the equipment / tool.

[0016] According to various embodiments of the invention, the device is constituted by a combustion engine and each tool is constituted by an actuator configured for operating a gas exchange valve of the combustion engine.

[0017] According to various embodiments of the invention, a combustion engine includes a cylinder head and a head cover which together define a head chamber, an actuator is arranged in the head chamber, and pressure chambers of cylinders of a hydraulic buffer unit are in fluid communication with the head chamber.

[0018] According to various embodiments of the present invention, such an actuator comprises an actuator piston arranged to shift the gas exchange valve, and wherein the actuator comprises at least one inlet opening for a pressure fluid and at least one outlet opening for a pressure fluid, wherein the at least one outlet opening is fluidly connected to the cylinder head chamber, and the displacement of the actuator piston is implemented by means of the pressure fluid.

[0019] Further advantages and features of the present invention will become apparent from the other dependent claims and from the following detailed description of preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other features and advantages of the present invention will be more fully understood through the following detailed description of the preferred embodiments in conjunction with the accompanying drawings, in which:

[0021] Figure 1 is a schematic cross-sectional side view of a portion of the apparatus of the present invention,

[0022] Figure 2 is a schematic cross-sectional side view of a portion of a combustion engine,

[0023] Figures 3 to 6schematic cross-sectional side views showing the actuator / tool ​​in different operating states, and

[0024] Figure 7 is a partial schematic cross-sectional perspective view of a cylinder head of a combustion engine. DETAILED DESCRIPTION

[0025] First reference Figure 1 , which is a schematic diagram of a portion of the apparatus of the present invention, generally designated 1. The apparatus 1 utilizes hydraulic fluid in connection with the operation of the apparatus 1, i.e., the hydraulic fluid flows between different locations in the apparatus so as to cause the apparatus 1 to perform a useful task or in response to the apparatus performing a useful task. The apparatus 1 includes a plurality of tools, generally designated 2, having elements / components 3 that are in motion during operation of the apparatus 1. The plurality of tools 2 are hydraulically interconnected. The apparatus 1 includes a hydraulic manifold 4, which is configured for storing pressurized hydraulic fluid and supplying hydraulic fluid to the plurality of tools 2.

[0026] The hydraulic manifold 4 may be constituted by a conduit provided in the body 5 of the device 1 , or by a separate pipe / component being part of the device 1 .

[0027] According to various embodiments, the hydraulic manifold 4 of the device 1 is also configured to receive hydraulic fluid from a plurality of tools 2. Therefore, according to other embodiments, the hydraulic fluid is supplied from the manifold 4 to the tools 2, and then the hydraulic fluid is discharged to a suitable location inside or outside the device 1, such as to an oil sump or a compressor (not disclosed), and then returned to the manifold 4. A combination can also be envisioned, that is, a portion of the hydraulic fluid is discharged from the tools 2, and a portion of the hydraulic fluid is directly returned to the manifold 4.

[0028] Each tool 2 comprises at least one hydraulic chamber 6 for containing hydraulic fluid, wherein the hydraulic chamber 6 has a changing volume during operation of the tool 2, ie in response to or in connection with a displacement / movement of the element 3. The displacement / movement of the element 3 may be, for example, a reciprocating or a rotating movement.

[0029] Each tool 2 comprises a communication conduit 7 extending between a hydraulic chamber 6 and a hydraulic manifold 4. A portion of the communication conduit 7 may be located outside the tool 2, for example in the body 5 of the device 1.

[0030] Importantly, each tool 2 includes a hydraulic buffer unit, generally designated 8. The buffer unit 8 is configured to prevent the propagation of hydraulic pulsations between the tool 2 and the hydraulic manifold 4 in response to the changing volume of the hydraulic chamber 6. Thus, the buffer unit 8 is configured so that the operation of each tool 2 does not adversely affect the operation of another tool 2, which involves the supply of hydraulic fluid from the manifold 4.

[0031] The hydraulic buffer unit 8 includes a buffer chamber 9 having a volume that changes in response to a changing volume of the hydraulic chamber 6. Therefore, when the volume of the hydraulic chamber 6 of the tool 2 increases, the volume of the buffer chamber 9 decreases, that is, at least a portion of the hydraulic fluid supplied to the hydraulic chamber 6 of the tool 2 is supplied from the buffer chamber 9 of the buffer unit 8 as the tool 2 is operated, so as to reduce the pulsation effect in the hydraulic manifold 4. According to various embodiments, when the volume of the hydraulic chamber 6 of the tool 2 decreases, the volume of the buffer chamber 9 increases, that is, at least a portion of the hydraulic fluid returned from the hydraulic chamber 6 of the tool 2 is returned to the buffer chamber 9 of the buffer unit 8 as the tool 2 is operated, so as to reduce the pulsation effect in the hydraulic manifold 4. The buffer chamber 9 of the buffer unit 8 may, for example, include a flexible bellows / membrane, one or more displaceable walls, and the like.

[0032] The buffer chamber 9 is in fluid communication with the communication conduit 7 , and the pressurized hydraulic fluid is used to increase the volume of the buffer chamber 9 .

[0033] According to various embodiments, for example Figure 1 In the disclosed embodiment, the hydraulic buffer unit 8 includes a cylinder 10 accommodating a piston 11, wherein the piston 11 can be reciprocally displaced in the cylinder 10. The piston 11 separates the buffer chamber 9 and the pressure chamber 12 in the cylinder 10 from each other. The pressure chamber 12 of each buffer unit 8 is preferably connected to a pressure fluid manifold 13 including a pressurized pressure fluid (e.g., gas / air). Therefore, the pressure chamber 12 accommodates a pressure fluid, which is used to displace the piston 11 toward the buffer chamber 9 so as to reduce the volume of the buffer chamber 9. The buffer chamber 9 is in fluid communication with the connecting conduit 7, and the pressurized hydraulic fluid is used to displace the piston 11 toward the pressure chamber 12 so as to increase the volume of the buffer chamber 9.

[0034] The pressure level in the pressure fluid manifold 13 is preferably adjustable to suit the operating conditions of the device 1, i.e. the higher the rpm / frequency of the device 1, the higher the pressure in the pressure fluid manifold 13. Alternatively, the pressure chamber 12 of each buffer unit 8 may also be a closed chamber.

[0035] Preferably, in addition to the pressure fluid, the pressure chamber 12 also accommodates a spring 14 for displacing the piston 11 toward the damping chamber 9 in order to reduce the volume of the damping chamber 9 .

[0036] In response to the volume of the hydraulic chamber 6 of the tool 2 temporarily not changing during the operation of the tool 2, the piston 11 is preferably displaced toward a rest position located between the two end positions in the cylinder 10. Therefore, when the tool 2 does not receive hydraulic fluid or does not return hydraulic fluid to the hydraulic manifold 4, as long as there is a pressure difference between the pressure chamber 12 and the buffer chamber 9, the buffer chamber 9 is still in fluid communication with the hydraulic manifold 4, and the piston 11 will be displaced toward the rest position (i.e., the equilibrium position in the cylinder 10). Therefore, when the pressure in the buffer chamber 9 of the cylinder 10 is equal to the pressure in the pressure chamber 12 of the cylinder 10, the piston 11 is located in the rest position between the two end positions in the cylinder 10.

[0037] According to various embodiments, when the piston 11 is in said rest position, the maximum variation in volume of the hydraulic chamber 6 of the tool 2 is equal to or less than the idle volume of the buffer chamber 9 of the cylinder 10. Therefore, in these cases, unfavorable pulsations of the hydraulic fluid are not propagated to the hydraulic manifold 4.

[0038] According to various embodiments, when piston 11 is in said rest position, the maximum variation in volume of hydraulic chamber 6 of tool 2 is equal to or less than the free volume of pressure chamber 12 of cylinder 10. Thus, in these conditions, unfavorable pulsations of the hydraulic fluid are not propagated to hydraulic manifold 4.

[0039] According to the embodiment in which the pressure chamber 12 includes a spring 14 , the piston 11 is located at the rest position when the pressure in the buffer chamber 9 is equal to the sum of the pressure of the pressure fluid in the pressure chamber 12 of the cylinder 10 and the spring force of the spring 14 .

[0040] When the element 3 of the tool 2 is displaced during operation of the tool 2, i.e., when the volume of the hydraulic chamber 6 changes, the volume of the buffer chamber 9 changes rapidly in response to the changing volume of the hydraulic chamber 6. Thereafter, when the element 3 of the tool 2 is stationary, i.e., when the volume of the hydraulic chamber 6 is unchanged / fixed, the volume of the buffer chamber 9 is allowed to change in order to return the piston 11 to the rest position.

[0041] According to various embodiments, the pressure in the hydraulic manifold 4 is adjustable, wherein the pressure level in the hydraulic manifold 4 is adjusted based on the prevailing pressure level in the pressure chamber 12 of the cylinder 10. Thus, in some embodiments based on the prevailing pressure level in the pressure fluid manifold 13.

[0042] A buffer unit 8 is associated with each tool 2, i.e., it is part of the tool 2 or is positioned in direct connection with the tool. According to the disclosed embodiment, the hydraulic buffer unit 8 is located at the interface between the tool 2 and the body 5 of the device 1, i.e., on top of the tool 2 or between the tool 2 and the body 5 of the device.

[0043] Reference now Figures 2 to 7, wherein the device 1 is constituted by a combustion engine, and wherein the tool 2 is constituted by an actuator configured for operating a gas exchange valve 15 of the combustion engine. Therefore, in this document, the term "combustion engine" shall be considered equivalent to the device and have the same reference numerals, and the term "actuator" shall be considered equivalent to the tool and have the same reference numerals.

[0044] Figure 2 A schematic diagram of a portion of a combustion engine 1 of the present invention is disclosed. The combustion engine 1 comprises a cylinder block 16 having at least one cylinder 17. The cylinder block 16 may comprise one or more cylinders 17. In the disclosed embodiment, one cylinder 17 is described, however it should be appreciated that in embodiments where the combustion engine comprises more cylinders, the equipment described below with respect to the illustrated cylinder 17 preferably applies to all cylinders of the combustion engine 1.

[0045] Furthermore, the combustion engine 1 comprises a piston 18 axially displaceable in said cylinder 17. The movement, axial reciprocating displacement, of the piston 18 is transmitted in a conventional manner to a connecting rod 19 connected to the piston 18, which in turn is connected to a crankshaft (not shown) and drives the crankshaft in rotation.

[0046] The combustion engine 1 further comprises a cylinder head 20 which, together with the cylinder 17 and the piston 18, delimits a combustion chamber 21. In the combustion chamber 21, ignition of the mixture of fuel and air takes place in a conventional manner, which will not be described further herein. The cylinder head 20 comprises a first controllable engine valve 15, also called a gas exchange valve.

[0047] In the disclosed embodiment, the cylinder head further comprises a second controllable engine valve 22. In the embodiment shown, the first engine valve 15 constitutes an inlet valve arranged to be selectively opened / closed to supply air to the combustion chamber 21. In the embodiment shown, the second engine valve 22 constitutes an air outlet valve or exhaust valve arranged to be selectively opened / closed to discharge exhaust gases from the combustion chamber 21.

[0048] The combustion engine 1 further comprises a first valve actuator 2, which is operatively connected to the first engine valve 15 and is arranged in a closed pressure fluid circuit of the combustion engine 1. The first valve actuator 2 comprises at least one inlet opening 23 for a pressure fluid and at least one outlet opening 24 for a pressure fluid. The pressure fluid may be a gas or a gas mixture, preferably air or nitrogen. Alternatively, the pressure fluid may also be a hydraulic fluid. In the embodiment shown, the combustion engine 1 further comprises a second valve actuator 2, which is operatively connected to the second engine valve 22 and is arranged in parallel with the first valve actuator 2 in the closed pressure fluid circuit.

[0049] Each valve actuator 2 can be operatively connected to one or more gas exchange valves. For example, the combustion engine may include two inlet valves driven by the same valve actuator. However, each valve actuator can also drive an engine valve to achieve the maximum possible control over the operation of the combustion engine 1.

[0050] The combustion engine 1 further comprises a cylinder head chamber 25 which forms part of the closed pressure fluid circuit and is delimited by the cylinder head 20 and a cylinder head cover 26. In the embodiment shown, the cylinder head cover 26 is divided into two elements. The outlet opening 24 of the actuator 2 is in fluid communication with the cylinder head chamber, i.e. the pressure fluid leaving the actuator 2 flows out into the cylinder head chamber via the at least one outlet opening 24.

[0051] Preferably, the entire actuator 2 is arranged in the cylinder head chamber 25, and also preferably, the actuator 2 is directly or indirectly connected in a releasable manner to the cylinder head cover 26. In this embodiment, the actuator 2 is thus "suspended" in the cylinder head cover 26 without contacting the cylinder head 20. In an exemplary alternative embodiment, the actuator 2 can be directly or indirectly connected in a releasable manner to the cylinder head 20 in the cylinder head chamber 25.

[0052] Now the main reference Figures 3 to 6 , which disclose the actuator 2 in different operating states.

[0053] The actuator 2 comprises an actuator piston disc 27 and an actuator cylinder 28 which delimits a cylinder volume which is open downwards, at least partially. The actuator piston disc 27 divides the cylinder volume into a first upper portion 29 and a second lower portion 30 and is axially displaceable in the actuator cylinder 28. The actuator piston disc 27 constitutes part of an actuator piston which is equivalent to the moving element 3 of the tool 2. The actuator piston 3 is arranged to contact and drive the engine valve 15.

[0054] The lower part 30 of the cylinder volume of the actuator 2 is in fluid communication with said cylinder head chamber 25. In this way it is ensured that when the actuator piston 3 is in the upper turn position, the same pressure acts on the actuator piston disc 27 from the first / upper part 29 of the cylinder volume and from the second / lower part 30 of the cylinder volume, respectively.

[0055] According to various embodiments, the actuator 2 comprises a first controllable inlet valve 31 and a second controllable inlet valve 32, which are arranged in an inlet channel 33 and are arranged to open / close the inlet channel 33, a controllable outlet valve 34, which is arranged in an outlet channel 35 and is arranged to open / close the outlet channel 35, a hydraulic circuit, generally referenced 36, which in turn comprises a non-return valve 37 arranged to allow filling of the hydraulic circuit 36, and a controllable drain valve 38, which is arranged to control the draining of the hydraulic circuit 36. The inlet channel 33 is arranged between the pressure fluid inlet opening 23 and the first part 29 of the cylinder volume of the cylinder 28. The outlet channel 35 is arranged between the pressure fluid outlet opening 24 and the first part 29 of the cylinder volume of the cylinder 28.

[0056] The portion of the hydraulic circuit 36 ​​defined by the non-return valve 37 and the controllable drain valve 38 is equivalent to the hydraulic chamber 6 of the tool 2. The actuator 2 comprises a hydraulic buffer unit 8, which is configured as described above. The pressure chamber 12 of the cylinder 10 of the buffer unit 8 is in fluid communication with the cylinder head chamber 25. Therefore, in this case, the pressure fluid manifold 13 is constituted by the cylinder head chamber 25.

[0057] The hydraulic manifold 4 is arranged in the cylinder head cover 26. In this case, therefore, the main body 5 of the device is constituted by the cylinder head cover 26. The communication duct 7 is part of the hydraulic circuit 36.

[0058] The actuator piston 3 further comprises an actuator piston rod 39, wherein the actuator piston rod 39 is arranged to guide the actuator piston 3 during axial displacement. The actuator 2 comprises an actuator piston rod opening 40 receiving said actuator piston rod 39, wherein an upper end 41 of the actuator piston rod 39 is arranged to be displaced in axial direction relative to said hydraulic circuit 36 ​​in relation to an axial displacement of the actuator piston disc 27 within the cylinder volume.

[0059] It should be noted that these controllable valves in the valve actuator 2 are schematically depicted and can be composed of, for example, sliding valves, seat valves, etc. In addition, a plurality of the controllable valves described above can be composed of a single body. Each valve can also be electrically controlled directly or indirectly. "Directly electrically controlled" means that the position of the valve is directly controlled by, for example, an electromagnetic device, and "indirectly electrically controlled" means that the position of the valve is controlled by a pressure fluid, which in turn is controlled by, for example, an electromagnetic device.

[0060] exist Figure 3 In the embodiment, the actuator 2 is in the inactive state and is ready to be set to the active state. The second controllable inlet valve 32, the outlet valve 34 and the drain valve 38 of the hydraulic circuit 36 ​​are closed. The first controllable inlet valve 31 is open. The actuator piston plate 27 is correspondingly in the upper position, and the actuator piston 3 is ready to open the engine valve ( Figure 2-6 Not shown, see Figure 1 ). The controllable drain valve 38 and the controllable outlet valve 34 can be controlled simultaneously. The controllable drain valve 38 and the controllable outlet valve 34 can be operated by a single electromagnetic solenoid 42. The first controllable inlet valve 31, the second controllable inlet valve 32, the controllable outlet valve 34 and the controllable drain valve 38 can be controlled by a control unit. Figure 3 In the embodiment of the present invention, the first controllable inlet valve 31 is inactive in its open position, while the second controllable inlet valve 32, the controllable outlet valve 34 and the controllable drain valve 38 are inactive in their closed positions. This arrangement can help save energy consumed by the actuator 2 when it is in operation.

[0061] exist Figure 4 In the embodiment, the second controllable inlet valve 32 has been opened to allow the pressure fluid with high pressure to fill the upper part 29 of the cylinder volume, after which the actuator piston plate 27 starts to move as shown in FIG. Figure 4 31 , i.e., it is displaced downward. The check valve 37 of the hydraulic circuit 36 ​​allows the hydraulic fluid to be sucked into the hydraulic chamber 6 and replace the volume left by the actuator piston 3. When the first controllable inlet valve 31 and the second controllable inlet valve 32 are opened at the same time, i.e., overlapped, the pressure fluid can only fill the upper part 29 of the cylinder volume. The first controllable inlet valve 31 and the second controllable inlet valve 32 can be in the open position at the same time during the so-called overlap period. The overlap period is short compared to the opening time of the first controllable inlet valve 31 and is also short compared to the opening time of the second controllable inlet valve 32. It should be noted that the first controllable inlet valve 31 and the second controllable inlet valve 32 do not need to be fully opened during the overlap period, i.e., the first controllable inlet valve 31 and / or the second controllable inlet valve 32 can be partially opened during the overlap period. "Partially open" refers to a specific valve in a movement from fully closed to fully open or from fully open to fully closed. The final action position of the piston disc 3 is defined by the overlap period and the pressure of the pressure fluid. The first controllable inlet valve 31 is operated by an electromagnetic solenoid 43. The second controllable inlet valve 32 is operated by an electromagnetic solenoid 44. The overlapping period is typically less than 3 ms. In various example embodiments, the overlapping period is in the range of 1 ms to 2 ms.

[0062] When the actuator piston 3 is displaced downward and the volume of the hydraulic chamber 6 increases, the piston 11 of the damping unit 8 is displaced toward the damping chamber 9 .

[0063] exist Figure 5, the first controllable inlet valve 31 has been closed in order to stop the supply of pressure fluid to the upper part 29 of the cylinder volume. Thereafter, the second controllable inlet valve 32 has also been closed in order to return to its default / initial position. The pressure fluid in the upper part 29 of the cylinder volume cannot displace the actuator piston disc 27 further. By keeping the drain valve 38 of the hydraulic circuit 36 ​​closed simultaneously with the non-return valve 37 which automatically closes the hydraulic circuit 36, the actuator piston disc 27 is kept in place (locked) in its lower position for a desired amount of time.

[0064] When the actuator piston 3 is stationary, the piston 11 of the damping unit 8 is displaced towards the pressure chamber 12 and towards the rest position.

[0065] According to the disclosed embodiment, before the first inlet valve 31 is opened, the second inlet valve 32 is set to a fully closed position (i.e. Figure 5 ), thereafter, the first inlet valve 31 is opened (i.e. Figure 6 ).

[0066] exist Figure 6 In the embodiment, the outlet valve 34 is opened to allow the discharge of the pressurized fluid from the upper part 29 of the cylinder volume, and in addition, the drain valve 38 of the hydraulic circuit 36 ​​is also opened, after which the actuator piston plate 27 is as shown in FIG. Figure 6 As a result, the hydraulic fluid is discharged from the hydraulic chamber 6 of the hydraulic circuit 36, and the pressure fluid is discharged from the upper part 29 of the cylinder volume to the cylinder head chamber 25.

[0067] When the actuator piston 3 is displaced upward and the volume of the hydraulic chamber 6 is reduced, the piston 11 of the damping unit 8 is displaced toward the pressure chamber 12 .

[0068] The hydraulic fluid is preferably oil, most preferably the same type of oil as the normal motor oil of the combustion engine 1 .

[0069] Reference now Figure 7 , which schematically shows the cylinder head 20 and the cylinder head cover 26 .

[0070] The cylinder head cover 26 comprises a pressure fluid manifold 45, which is connected to at least one inlet opening 23 of the actuator 2. The pressure fluid manifold 45 extends along the axial length of the cylinder head cover 26. The pressure fluid manifold 45 forms a part of a main pressure fluid channel 46, which extends from a compressor 47 to the at least one inlet opening 23 of the actuator 2. The compressor 47 is arranged to supply the valve actuator with pressure fluid under high pressure. In addition, a secondary pressure fluid channel 48 (see also Figure 1 ) extends from the cylinder head chamber 25 to the compressor 47.

[0071] The compressor 47 has a variable compressor capacity / displacement, or has an output that can be regulated by other means, and is usually driven by the crankshaft of the combustion engine 1. At high speeds and high torque outputs, a higher pressure fluid is required in the main pressure fluid passage 46, while at low speeds and low torque outputs, a lower pressure fluid is required in the main pressure fluid passage 46.

[0072] The cylinder head cover 26 also comprises a hydraulic fluid manifold 4, which is connected to the communication duct 7 of the hydraulic circuit 36 ​​of the valve actuator 2. The hydraulic fluid manifold 4 extends along the axial length of the cylinder head 26 and is parallel to the pressure fluid manifold 45. A pump 49 or similar device is arranged to supply pressurized hydraulic fluid to the hydraulic fluid manifold 4 via a duct 50.

[0073] The cylinder head cover 26 may also include all necessary electrical infrastructures (not shown), in particular electrical infrastructures for the control valve actuators 2 , electrical infrastructures for various sensors and the like.

[0074] Possible modifications of the invention

[0075] The present invention is not limited to the embodiments described above and shown in the drawings, which are mainly for illustration and example. This patent application is intended to cover all adjustments and modifications of the preferred embodiments described herein, so the present invention is defined by the attached claims and their equivalents, and the equipment can be modified in all conceivable ways within the scope of the attached claims.

[0076] It should also be noted that all information on / related to terms such as above, below, up, down, etc. should be interpreted / read with respect to the device according to the orientation of the drawings, and the orientation of the drawings allows the reference numerals to be read in the correct manner. Therefore, such terms only represent the mutual relationships in the illustrated embodiments, and these relationships may be changed if the device of the present invention is provided with another structure / design.

[0077] It should also be noted that even if it is not explicitly stated that features of a specific embodiment can be combined with features of another embodiment, it should be deemed that the combination should be deemed / considered to be obvious when the combination is feasible.

Claims

1. A device (1), comprising: - a plurality of tools (2), each tool having at least one hydraulic chamber (6) for hydraulic fluid, a hydraulic manifold (4) configured to store pressurized hydraulic fluid and to supply the plurality of tools (2), Each tool (2) comprises a communication conduit (7) extending between the hydraulic chamber (6) and the hydraulic manifold (4), the hydraulic chamber (6) having a variable volume during operation of the tool (2), Characterized in that each tool (2) includes a hydraulic buffer unit (8) for preventing hydraulic pulsations from propagating between the tool (2) and the hydraulic manifold (4) in response to a changing volume of the hydraulic chamber (6), wherein the hydraulic buffer unit (8) has a buffer chamber (9) having a volume that changes in response to a changing volume of the hydraulic chamber (6).

2. The device (1) according to claim 1, wherein: The hydraulic buffer unit (8) comprises a cylinder (10) accommodating a piston (11), wherein the piston (11) separates the buffer chamber (9) and the pressure chamber (12) from each other, wherein the piston (11) is reciprocally displaceable in the cylinder (10). - wherein the pressure chamber (12) contains a pressure fluid, the pressure fluid being used to displace the piston (11) toward the buffer chamber (9) so as to reduce the volume of the buffer chamber (9), and - wherein the buffer chamber (9) is in fluid communication with the communication duct (7), and the pressurized hydraulic fluid is used to displace the piston (11) toward the pressure chamber (12) so as to increase the volume of the buffer chamber (9).

3. The device (1) according to claim 2, wherein: The pressure chamber (9) accommodates the pressure fluid and a spring (14), and the spring (14) is used to displace the piston (11) toward the buffer chamber (9) so as to reduce the volume of the buffer chamber (9).

4. The device (1) according to claim 2 or 3, wherein: In response to the volume of the hydraulic chamber (6) not changing temporarily during operation of the tool (2), the piston (11) is displaced towards a rest position located between two end positions within the cylinder (10).

5. The device (1) according to any one of claims 2 to 4, wherein: The piston (11) is associated with a rest position located between two end positions in the cylinder (10), and when the piston (11) is in the rest position, the pressure in the buffer chamber (9) of the cylinder (10) is equal to the pressure in the pressure chamber (12) of the cylinder (10).

6. The device (1) according to any one of claims 2 to 5, wherein: The pressure in the hydraulic manifold (4) is adjustable, and the pressure level in the hydraulic manifold (4) is adjusted based on the pressure level in the pressure chamber (12) of the cylinder (10) of the hydraulic buffer unit (8).

7. The device (1) according to any one of claims 2 to 6, wherein: The piston (11) is associated with a rest position located between two end positions in the cylinder (10), and wherein, when the piston (11) is in the rest position, the maximum volume change of the hydraulic chamber (6) of the tool (2) is equal to or less than the free volume of the buffer chamber (9) of the cylinder (10).

8. The device (1) according to any one of claims 2 to 7, wherein: The piston (11) is associated with a rest position located between two end positions in the cylinder (10), and wherein, when the piston (11) is in the rest position, the maximum volume change of the hydraulic chamber (6) of the tool (2) is equal to or less than the free volume of the pressure chamber (12) of the cylinder (10).

9. The device (1) according to any preceding claim, wherein: The hydraulic buffer unit (8) of each tool (2) is located at the interface between the tool (2) and the body (5) of the device (1) including the hydraulic manifold (4).

10. The device (1) according to any preceding claim, wherein: The device (1) is constituted by a combustion engine, and wherein the means (2) is constituted by an actuator configured for operating a gas exchange valve (15) of the combustion engine.

11. The device according to claim 10, wherein: The combustion engine (1) comprises a cylinder head (20) and a cylinder head cover (26), the cylinder head and the cylinder head cover together defining a cylinder head chamber (25), the actuator (2) being arranged in the cylinder head chamber (25), and the pressure chamber (12) of the cylinder (10) of the hydraulic buffer unit (8) being in fluid communication with the cylinder head chamber (25).

12. The device (1) according to claim 11, wherein The hydraulic manifold (4) is arranged in the cylinder head cover (26).

13. The device (1) according to claim 11 or 12, wherein: The actuator (2) comprises an actuator piston (3) arranged to displace the gas exchange valve (15), and wherein the actuator (2) comprises at least one inlet opening (23) for a pressure fluid and at least one outlet opening (24) for the pressure fluid, the at least one outlet opening (24) for the pressure fluid being in fluid communication with the cylinder head chamber (25), and the displacement of the actuator piston (3) is performed by the pressure fluid.

14. The device (1) according to claim 13, wherein: The cylinder head cover (26) comprises a pressure fluid manifold (45) which is connected to the at least one inlet opening (23) for pressure fluid of the actuator (2).

Images