Control device for an electric actuator

• US 9,617,713 B2
• Filed: 05/11/2011
• Issued: 04/11/2017
• Est. Priority Date: 05/20/2010
• Status: Expired due to Fees

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Take, Hiroaki, Kawaguchi, Tadashi, Morinaga, Jun
• Primary Examiner(s): Fennema, Robert
• Assistant Examiner(s): Stevens, Thomas
• Application Number:
  US13/583,972
• Publication Number:
  US 20130073111A1
• Time in Patent Office: 2,162 Days
• Field of Search: 700301, 60431
• CPC Class Codes: E02F 9/123 Drives or control devices specially adapted therefor E02F9/125 and E02F9/128 take precedence
• CPC Class Codes: E02F 9/2095 Control of electric, electro-mechanical or mechanical equipment not otherwise provided for, e.g. ventilators, electro-driven fans control of hydraulic driven equipment E02F9/22
• CPC Class Codes: E02F 9/2221 Control of flow rate; Load sensing arrangements E02F9/2203 take precedence over E02F9/2221
• CPC Class Codes: F15B 2211/20553 with pilot circuit, e.g. for controlling a swash plate
• CPC Class Codes: F15B 2211/275 Control of the prime mover, e.g. hydraulic control
• CPC Class Codes: F15B 2211/50527 using cross-pressure relief valves
• CPC Class Codes: F15B 2211/6316 the pressure being a pilot pressure
• CPC Class Codes: F15B 2211/7058 Rotary output members

Abstract

A control device of an electric actuator adapted to perform a forward-reverse movement includes a control unit adapted to be operated in a forward direction or a reverse direction in accordance with the forward-reverse movement of the electric actuator. It also includes a pilot circuit, which is connected to the control unit and which generates a forward pilot pressure or a reverse pilot pressure in accordance with the forward operation or the reverse operation of the control unit. The control device has a differential pressure acquiring unit that acquires a differential pressure between a pilot pressure corresponding to an operation direction of the control unit and a pilot pressure, in a direction opposite to the operation direction, and it has a control command generator that generates a control command for controlling the electric actuator based on the differential pressure acquired by the differential pressure acquiring unit. The control device includes a drive controller for controlling a drive of the electric actuator based on the generated control command.

Claims

1. Hybrid work equipment comprising:

an electric actuator that is adapted to perform a forward-reverse movement;

a control unit that is adapted to be operated by an operator in a forward direction or a reverse direction to drive the electric actuator;

a pilot circuit that is connected with the control unit, the pilot circuit being configured to generate a forward pilot pressure or a reverse pilot pressure in accordance with the forward operation or the reverse operation of the control unit; and

a control device configured to receive the forward pilot pressure and the reverse pilot pressure generated by the pilot circuit and to output a drive command to the electric actuator, the forward-reverse movement of the electric actuator being commanded by the drive command,

wherein the control device comprises;

a differential pressure acquiring unit that is configured to acquire a differential pressure between a pilot pressure of the pilot circuit corresponding to the operation direction of the control unit and a pilot pressure of the pilot circuit in a direction opposite to the operation direction;

a control command generator that is configured to generate a control command to the electric actuator based on the differential pressure of the pilot circuit acquired by the differential pressure acquiring unit; and

a drive controller that is configured to control a drive of the electric actuator based on the control command generated by the control command generator.

2. The hybrid work equipment according to claim 1, wherein the differential pressure acquiring unit comprises:

a forward pressure detector that is configured to detect the forward pilot pressure of the pilot circuit;

a reverse pressure detector that is configured to detect the reverse pilot pressure of the pilot circuit; and

a differential pressure calculating section that is configured to calculate a differential pressure between the forward pilot pressure detected by the forward pressure detector and the reverse pilot pressure detected by the reverse pressure detector.

3. The hybrid work equipment according to claim 1, wherein the pilot circuit comprises:

a first pilot valve connected to the control unit and configured to be operated based on the control unit being operated in the forward direction;

a second pilot valve connected to the control unit and configured to be operated based on the control unit being operated in the reverse direction; and

a pipe line defining a closed circuit from the first pilot valve to the second pilot valve in which a pressure oil flows.

4. The hybrid work equipment according to claim 1, wherein the differential pressure acquiring unit is configured to judge, based on the differential pressure being positive, that the control unit is operated in the forward direction and to judge, based on the differential pressure being negative, that the control unit is operated in the reverse direction.

5. The hybrid work equipment according to claim 1, wherein the electric actuator is configured to electrically drive a drive system of the hybrid work equipment.