Nabtesco

A drive system for an excavator, which is a work machine, includes an electric motor, a speed reducer, a control device, and a temperature sensor TS. The speed reducer is coupled to the electric motor. The speed reducer is configured to amplify torque of the electric motor and output the amplified torque to a driven object. The control device supplies electric power to the electric motor. The temperature sensor TS detects a temperature of the speed reducer. When the temperature detected by the temperature sensor TS is equal to or lower than a prescribed temperature, the control device executes a warm-up process to supply electric power to the electric motor. The control device executes the warm-up process while maintaining a rotation angle of an output shaft of the speed reducer within a predetermined range.

One object is to reduce a moment load acting on an electric actuator that drives an attachment. An excavator includes: a swing bracket rotatable about a swing axis relative to an upper body; a swing actuator configured to rotate the swing bracket; an electric actuator mounted to the swing bracket and configured to output a torque about an axis intersecting the swing axis; an attachment driven by the electric actuator; and a control device configured to perform specific control in which the swing actuator is controlled so as to maintain a constant rotational position of the swing bracket. When a load torque, which is a torque about the swing axis acting on the swing bracket during the specific control, has reached or exceeded a critical torque, the control device controls the swing actuator so as to reduce the load torque.

A processing device configured to execute: a first acquisition process of acquiring an input phase that is a rotational phase of a rotation input portion of a speed reducer, the rotation input portion rotating based on torque input to the speed reducer; a second acquisition process of acquiring an output phase that is a rotational phase of a rotation output portion of the speed reducer, the output portion rotating based on torque from the rotation input portion; a third acquisition process of acquiring an estimated phase based on a reduction ratio and the input phase; and a fourth acquisition process of acquiring a phase difference that is a difference between the output phase and the estimated phase; and an output process of outputting a backlash amount based on the phase difference.

It is desired to provide a working machine with improved work efficiency and power efficiency. A drive system of the working machine includes a rotating member configured to rotate relative to a connection portion; and an electric motor configured as a power source for the rotating member. The electric motor has a plurality of windings connected to an AC power source, and the drive system includes a switching circuit configured to switch a connection state of the windings between a first connection state and a second connection state in which the electric motor rotates at lower torque and higher rotational speed than in the first connection state.

It is desired to reduce power consumption of electric actuators. An excavator includes a first electric actuator configured to drive a first movable member, a second electric actuator configured to drive a second movable member connected to the first movable member, a brake device configured to apply a braking force to a first output shaft of the first electric actuator, and a control device. If reaction torque acting on the first output shaft as the second electric actuator outputs torque is greater than a threshold, the control device controls the first electric actuator such that the first output shaft outputs the torque in a direction opposite to the reaction torque. If the reaction torque is no more than the threshold, the control device causes the brake device to apply a braking force to the first output shaft and suspends power supply to the first electric actuator.

One object is to restrict a circumferential speed of a distal end of an attachment. An excavator includes: an attachment having a first movable member and a second movable member; and a drive unit having a first electric actuator having a first output shaft for rotating the first movable member and a second electric actuator having a second output shaft for rotating the second movable member. A control device performs: a first process to calculate an upper-limit rotational frequency of the first output shaft; and a second process to control the first electric actuator such that the rotational frequency of the first output shaft is lower than or equal to the upper-limit rotational frequency, and the first process is performed such that the upper-limit rotational frequency is lower as a distance from the first output shaft to a distal end of the attachment is longer.

A drive system of a working machine includes: an attachment including first and second members; a drive unit configured to drive the attachment, and a control device configured to control the drive unit. The control device stores positional relationship information indicating relationship between (i) first and second angular positions of the first and second members and (ii) positional relationship between a vehicle body and the attachment. The control device performs: an acquisition process in which the first and second angular positions are acquired; a calculation process in which positional relationship is calculated by applying the first and second angular positions to the positional relationship information; and a coping process in which a measure is taken to avoid interference between the attachment and the vehicle body if the positional relationship indicates that the shortest distance between the attachment and the vehicle body is less than a predetermined value.

An actuator system for a work machine includes an electromagnetic brake with an excitation coil and a control device controlling energization of an electric motor and the excitation coil. The electromagnetic brake brakes a drive shaft of the electric motor when the excitation coil is in a non-excited state and to release the brake on when the excitation coil is in an excited state. The control device executes processes of: deenergizing the electric motor and the excitation coil; obtaining a transition of an angular position of the drive shaft from a time point at which execution of the first process is completed; calculating a rotation amount and direction of the drive shaft from an initial position; and when the rotation amount of the drive shaft becomes greater than a predetermined value, controlling the energization of the electric motor to apply a torque to the drive shaft in the opposite rotation direction.

The invention relates to a steering system (1) comprising an electric motor (2) and a steering gear device (3), which has a first steering gear input shaft (4) that is couplable to a steering shaft, a second steering gear input shaft (5) that is drivably coupled to the electric motor (2), and a steering gear output shaft (6), wherein the torque path from the first steering gear input shaft (4) to the steering gear output shaft (6) comprises at least two gear stages connected in series, and wherein a first of the gear stages is formed by a cycloidal gear (21) comprising at least one externally toothed cycloidal disc (23, 24) which is in engagement with roller pins (25) arranged along a circumferential circle, wherein movement of the cycloidal disc (23, 24) is generated by a plurality of eccentrically arranged eccentric shafts (26) driven to rotate, each of which is rotatably supported about its own axis. The steering system (1) is characterized in that each eccentric shaft (26) has an eccentric shaft gear (28), which is a component of a second gear stage of the at least two gear stages connected drivably in series.

The invention relates to a steering system (1) consisting of steering system components including at least one electric motor (2), and a steering gear device (3) having a first steering gear input shaft (4) couplable to a steering shaft and a second steering gear input shaft (5) drivably coupled to the electric motor (2), and having a steering gear output shaft (6), and a steering gear device housing (7) which has fastening elements (8) for fastening the steering gear device housing (7) to a higher-level structure, in particular a vehicle body. The steering system (1) is characterized in that the steering gear device housing (7) is designed such that, with this housing (7), a steering system (1) that is mirror-symmetrical to the steering system (1) with respect to a mirror plane, in particular a vertical mirror plane, at least with regard to the arrangement and orientation of the first and second steering gear input shafts (4, 5), the steering gear output shaft (6), and the fastening elements (8), can be manufactured.