A servo valve unit capable of precisely controlling the position of a pneumatic cylinder that does not require a servo amplifier and a small sized and/or high durability servo valve unit are disclosed. The servo valve unit comprises a unit body having a first end portion and a second end portion, a first valve portion, a second valve portion, a first seal member that opens and closes the first valve portion, a second seal member that opens and closes the second valve portion, a first drive mechanism that drives the first seal member by a first electric pulse, a second seal member that drives the second seal member by a second electric pulse, a supply flow path that extends between the first end and the first valve, an exhaust flow path that extends between the second end and the second valve, a common flow path connected to the supply flow path and the exhaust flow path via the first valve portion and the second valve portion, and a drive flow path connected to the pneumatic actuator. The first drive mechanism and the second drive mechanism are arranged in a drive mechanism arrangement portion located between the first end portion and the second end portion. The drive air flow path can branch from a branch portion located between the drive mechanism arrangement portion and the first end portion and extends to the first end portion. Alternatively drive air flow path can branch from the common flow path from a branch portion located between the drive mechanism arrangement portion and the second end portion and extends to the second end portion.

Disclosed herein are embodiments of a lift apparatus and systems containing a support and at least one lift apparatus for moving a substrate between the support and a transfer plane, using a servo-control system. Further disclosed herein are methods for servo control of a lift apparatus and lifting a substrate off of a support or lowering the substrate onto the support.

Disclosed herein are embodiments of a lift apparatus and systems containing a support and at least one lift apparatus for moving a substrate between the support and a transfer plane, using a servo-control system. Further disclosed herein are methods for servo control of a lift apparatus and lifting a substrate off of a support or lowering the substrate onto the support.

To utilize and protect a mechanical load torque range of a servo drive in combination with a pump, a control unit is given a target system pressure as a reference variable and an actual system pressure as a control variable. An electric motor torque acting on a pump of the servo drive is specified by the control unit to an electric motor of the servo drive, a volume flow at the hydraulic load is generated by the pump, by which a mechanical load torque sets it at the electric motor and the actual system pressure is produced in the hydraulic load via the volume flow. A dynamic system variable of the hydraulic system is transmitted to the limiting unit. The limiting unit limits the motor torque transmitted by the control unit to the electric motor as a function of the value of the system variable.

To utilize and protect a mechanical load torque range of a servo drive in combination with a pump, a control unit is given a target system pressure as a reference variable and an actual system pressure as a control variable. An electric motor torque acting on a pump of the servo drive is specified by the control unit to an electric motor of the servo drive, a volume flow at the hydraulic load is generated by the pump, by which a mechanical load torque sets it at the electric motor and the actual system pressure is produced in the hydraulic load via the volume flow. A dynamic system variable of the hydraulic system is transmitted to the limiting unit. The limiting unit limits the motor torque transmitted by the control unit to the electric motor as a function of the value of the system variable.

A hydraulic module including a cylinder (2) which accommodates a piston (3) which delimits a chamber (4) which receives the brake fluid. The piston (3) is connected to the electric motor (5) of the module (1) by a recirculating ball screw (6), whose core (61) is fixedly connected to the piston (3) which itself is guided by needles (21) which are parallel to the axis (xx) of the piston (3) and with which notches (351) on the circumference of the piston (3) interact. The piston (3) is a piece, which is formed from a cylindrical body (32) made from anodized aluminum and an outer ring (35) made from steel, which is forcibly mounted on the edge (34) of the piston and is provided with notches (351) with a cross section which corresponds to the effective cross section of the needles (21).

In one aspect, a system for rephasing fluid-driven actuators includes a plurality of fluid-driven actuators fluidly coupled together in series. A controller is configured to monitor a position differential existing between current positions of rods of the actuators relative to a differential threshold based on sensor measurements. The actuators are out-of-phase when the monitored differential exceeds the threshold. The controller is also configured to initiate a flow of fluid to the actuators to rephase the actuators when the monitored differential exceeds the threshold. The controller is further be configured to continue to monitor the differential following initiation of the flow of fluid to the actuators. Additionally, the controller is configured to implement a control action associated with terminating the rephasing of the actuators when the monitored differential remains constant after a first time period has elapsed following initiation of the flow of fluid.

In one aspect, a system for rephasing fluid-driven actuators includes a plurality of fluid-driven actuators fluidly coupled together in series. A controller is configured to monitor a position differential existing between current positions of rods of the actuators relative to a differential threshold based on sensor measurements. The actuators are out-of-phase when the monitored differential exceeds the threshold. The controller is also configured to initiate a flow of fluid to the actuators to rephase the actuators when the monitored differential exceeds the threshold. The controller is further be configured to continue to monitor the differential following initiation of the flow of fluid to the actuators. Additionally, the controller is configured to implement a control action associated with terminating the rephasing of the actuators when the monitored differential remains constant after a first time period has elapsed following initiation of the flow of fluid.

Pressure compensating valves not fully closing at the stroke end are employed, and upon the operator's operation for the traveling, pilot primary pressure is reduced and supplied to remote control valves 34c-34h of non-travel operating devices. Thus, the inflow of the hydraulic fluid into non-travel actuators is suppressed and a necessary amount of hydraulic fluid for travel motors is secured in travel combined operation. Accordingly, when saturation occurs in a construction machine's hydraulic drive system performing the load sensing control due to combined operation with a great load pressure difference between two actuators, deceleration/stoppage of an actuator on the low load pressure side is prevented by preventing full closure of the pressure compensating valve on the low load pressure side, while also preventing deceleration/stoppage of a high load pressure actuator by securing a necessary amount of hydraulic fluid for the high load pressure actuator.

Pressure compensating valves not fully closing at the stroke end are employed, and upon the operator's operation for the traveling, pilot primary pressure is reduced and supplied to remote control valves 34c-34h of non-travel operating devices. Thus, the inflow of the hydraulic fluid into non-travel actuators is suppressed and a necessary amount of hydraulic fluid for travel motors is secured in travel combined operation. Accordingly, when saturation occurs in a construction machine's hydraulic drive system performing the load sensing control due to combined operation with a great load pressure difference between two actuators, deceleration/stoppage of an actuator on the low load pressure side is prevented by preventing full closure of the pressure compensating valve on the low load pressure side, while also preventing deceleration/stoppage of a high load pressure actuator by securing a necessary amount of hydraulic fluid for the high load pressure actuator.