A method for controlling movement of a movably mounted body (14) of a mechanical system (2, 56, 62). The mechanical system (2, 6, 62) includes a drive unit (4, 64), which is operated by a medium, and also a control valve (20, 22). The movably mounted body (14) is driven by the drive unit (4, 64). A drive movement of the drive unit (4, 64) is controlled with the aid of the control valve (20, 22). In order to avoid or reduce excitation of undesired vibrations in the mechanical system (2, 56, 62), it is proposed that the control valve (20, 22) be actuated using a control signal (u(t)) which comprises a first and also a further switching pulse (S.sub.1, S.sub.3) each having a prespecified pulse duration. The pulse duration of the first switching pulse (S.sub.1) is equal to the pulse duration of the further switching pulse (S.sub.3). A time difference (Δt.sub.1-3) between the start of the first pulse (S.sub.1) and the start of the further switching pulse (S.sub.3) is matched to a natural period duration of the mechanical system (2, 56, 62).

An accumulator for storing fluid that includes a shell that defines an interior volume of the accumulator. The shell includes at least one port for providing fluid to a fluid system. The accumulator also includes an accumulator shaft disposed in the interior volume and extending at least partially across the interior volume from a first interior surface of the shell along a longitudinal axis of the shell, e.g., a central axis. The accumulator includes a piston-plate disposed in the interior volume such that the piston-plate and a second interior surface of the shell define a chamber in the interior volume. The accumulator further includes a motor disposed in the interior volume. The accumulator is configured such that rotational movement of the motor translates to linear movement of the piston-plate along the accumulator shaft.

In a hydraulic brake system, which includes: a hydraulic pump which is driven by an electric motor and has the purpose of generating a fluid volume flow for the hydraulic brake system; and a solenoid valve for controlling the fluid volume flow from the hydraulic pump to a wheel brake, a method includes actuating the solenoid valve in such a way that by this means a fluid pulsation at the wheel brake is counteracted. Furthermore, the method may be implemented in a corresponding device.

A hydraulic pressure supply device includes: a hydraulic pump capable of changing a discharge capacity; an electric motor capable of changing a rotational frequency; a discharge capacity adjustment mechanism capable of adjusting the discharge capacity of the pump between a maximum and minimum discharge capacity; a pressure detector configured to detect pressure of an operating liquid discharged from the pump; a rotational frequency detector configured to detect the rotational frequency of the motor; and a controller configured to control operations of the motor and adjustment mechanism based on the rotational frequency, detected by the detector, to keep pressure of an actuator at arbitrary pressure, wherein, the controller controls the operation of the adjustment mechanism so the discharge capacity of the pump becomes a set lower limit discharge capacity. The set lower limit discharge capacity is set to be larger than the minimum discharge capacity and be adjustable by the controller.

[Object] To provide a noise reduction apparatus, an aircraft, and a noise reduction method capable of increasing the amount of noise reduction.

[Solving Means] The noise reduction apparatus 1 includes a porous plate 2 disposed to face a fluid flow, the porous plate 2 including a bend region 5 bent toward an upstream side of the fluid flow. The bend region 5 is provided at the end portion 6 of the porous plate 2, and has a concave R-shape on an upstream side of the fluid flow. Although the direction of the fluid flow is typically deflected toward the outside from the center of the porous plate 2 due to the porous plate 2, the deflected fluid easily passes through the porous plate 2 since the porous plate has the bend region 5. Thus, the shear layer of the fluid flow is weakened, the noise induced by the vortex is reduced, and it is possible to increase the reduction amount of noise.

In one aspect, a system for controlling an operation of an actuator mounted on a seed planting implement may include an actuator configured to adjust a position of a row unit of the seed planting implement relative to a toolbar of the seed planting implement. The system may also include a flow restrictor fluidly coupled to a fluid chamber of the actuator, with the flow restrictor being configured to reduce a rate at which fluid is permitted to exit the fluid chamber in a manner that provides damping to the row unit. Furthermore, the system may include a valve fluidly coupled to the flow restrictor in a parallel relationship such that the valve is configured to permit the fluid exiting the fluid chamber to flow through the flow restrictor and the fluid entering the fluid chamber to bypass the flow restrictor.

A work vehicle has a chassis, and a member connected to the chassis for movement with respect to the chassis. An actuator is connected to the chassis and to the member to move the member with respect to the chassis. A hydraulic circuit is connected to the actuator and a pump pressurizes fluid in the hydraulic circuit. An adjustable quarter wave tuner is connected to the hydraulic circuit. The adjustable quarter wave tuner has a length that is adjustable within a range of lengths to thereby reduce noise caused by the pump across a corresponding range of frequencies. In some embodiments, the member is a linear actuator, such as a hydraulic cylinder. In other embodiments, the member is a rotary actuator, such as a hydraulic motor.

A damping device, in particular for damping or preventing pressure surges, such as pulsations, in hydraulic supply circuits, preferably in the form of a silencer, having a damping housing (2) encompassing a damping chamber (10), wherein said damping housing (2) has at least one fluid inlet (6) and at least one fluid outlet (8) as well as a fluid receiving chamber extending between the fluid inlet (6) and the fluid outlet (8), wherein during operation of the device a fluid flow coming from the fluid inlet (6) passes through the damping chamber (10) towards the fluid outlet (8) and wherein a wall part of the fluid receiving chamber extends as a guide element (16) in at least one direction of extension transverse to the direction of the fluid flow, is characterized in that in the damping chamber (10) several guide elements (16) are provided, against which the fluid can flow and which alter the flow velocity in certain areas.

The invention relates to a control device for a hydraulic consumer (22), susceptible to vibrations, comprising a valve (24) having a control spool (40), which can be controlled by means of an actuating device (46), wherein the valve (24) has a pressure supply port (P), to which a pressure compensator valve can be connected, which can be supplied with pressure fluid from a pressure supply device, wherein the actuating device (46) has a motor (74) and wherein a load-pressure-dependent force on the control spool (40) can be generated by means of a control device (66). In accordance with the invention, this force at the control spool (40) acts on an electronic motor controller (208) of the DC motor (74), which detects a change of the force and acts as a damping of the vibrations of the consumer (22) against this change of force.

A damping device for fluids subject to pressure pulsations, having at least one hydraulic accumulator (2), the accumulator housing (4, 6) of which contains a movable separating element (18), which separates a gas side (14) from a fluid room (16) and can be pressurized by a fluid present in the fluid room (16), is characterized in that a damper housing (34) having a second fluid room (38) is provided as a component of the accumulator housing (4, 6), wherein through said second fluid room (38) the fluid subject to pressure pulsations can flow and the second fluid room (38) contains a second movable separating element (40), which separates the second fluid room (38) from the first fluid room (16) of the hydraulic accumulator (2) without dead space.