Electrohydraulic motor and hydraulic driving method

• US 6,772,671 B2
• Filed: 11/07/2002
• Issued: 08/10/2004
• Est. Priority Date: 11/07/2001
• Status: Expired due to Fees

• Current Assignee: Teijin Seiki Co., Ltd. (Nabtesco Corporation)
• Original Assignee: TS Corp. (Japan) (Nabtesco Corporation)
• Inventors: Shimizu, Nobuaki, Asano, Youji
• Primary Examiner(s): Lazo, Thomas E.
• Application Number:
  US10/289,567
• Publication Number:
  US 20030084781A1
• Time in Patent Office: 642 Days
• Field of Search: 911/80, 913/62, 913/63.R, 913/80, 915/03
• US Class Current: 91/363.00R
• CPC Class Codes: E02F 9/2232 using one or more variable displacement pumps
• CPC Class Codes: F15B 11/165 for adjusting the pump output or bypass in response to demand
• CPC Class Codes: F15B 2211/20538 constant capacity
• CPC Class Codes: F15B 2211/30505 Non-return valves, i.e. check valves
• CPC Class Codes: F15B 2211/3051 Cross-check valves
• CPC Class Codes: F15B 2211/3052 Shuttle valves
• CPC Class Codes: F15B 2211/30525 Directional control valves, e.g. 4/3-directional control valve
• CPC Class Codes: F15B 2211/31576 having a single pressure source and a single output member
• CPC Class Codes: F15B 2211/326 with follow-up action
• CPC Class Codes: F15B 2211/327 electrically or electronically
• CPC Class Codes: F15B 2211/40507 with constant throttles or orifices
• CPC Class Codes: F15B 2211/413 the positions being continuously variable, e.g. as realised by proportional valves
• CPC Class Codes: F15B 2211/41509 being connected to a pressure source and a directional control valve
• CPC Class Codes: F15B 2211/428 actuated by fluid pressure
• CPC Class Codes: F15B 2211/45 Control of bleed-off flow, e.g. control of bypass flow to the return line
• CPC Class Codes: F15B 2211/50518 using pressure relief valves
• CPC Class Codes: F15B 2211/50554 the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve
• CPC Class Codes: F15B 2211/5151 being connected to a pressure source and a directional control valve
• CPC Class Codes: F15B 2211/5158 being connected to a pressure source and an output member
• CPC Class Codes: F15B 2211/6051 having valve means between output member and the load sensing circuit
• CPC Class Codes: F15B 2211/6057 : using directional control valves
• CPC Class Codes: F15B 2211/6355 : having valve means
• CPC Class Codes: F15B 2211/7058 : Rotary output members
• CPC Class Codes: F15B 2211/715 : having braking means
• CPC Class Codes: F15B 9/12 : in which both the controlling element and the servomotor control the same member influencing a fluid passage and are connected to that member by means of a differential gearing
• CPC Class Codes: F15B 9/14 : with rotary servomotors

Abstract

There is provided an electrohydraulic motor that has a spool valve 110 for switching from each of drive positions (111, 112), in each of which a corresponding one of a main oil passage 230 and a return oil passage 240 is connected to a hydraulic actuator 130, to a neutral position, in which the hydraulic actuator 130 and each of the main oil passage 230 and the return oil passage 240 are disconnected, and vice versa. There is also provided a connection switch valve 140, which is connected to the main oil passage 230 and the return oil passage 240, for changing the connection between the main oil passage 230 and the return oil passage 240 in the neutral position 113. In response to an operation of the spool valve 110, the connection switch valve 140 connects the main oil passage 230 to the return oil passage 240 in the neutral position 113 and also disconnects the main oil passage 230 from the return oil passage 240 in the drive positions (111, 112).

Claims

1. An electrohydraulic motor, comprising:

hydraulic drive means for rotating an output shaft by a pressure of operation oil;

electric drive means for rotating a drive shaft according to an inputted electric signal;

drive switch means, connected to said hydraulic drive means, to a main oil passage for leading operation oil supplied from the exterior, and to a return oil passage for leading operation oil to the exterior, for switching connection between said hydraulic drive means and each of said main oil passage and said return oil passage; and

connection switch means, connected to said main oil passage and said return oil passage, for changing connection between said main oil passage and said return oil passage,

wherein said drive switch means responds to rotation of said drive shaft to thereby switch between a drive position, in which each of said main oil passage and said return oil passage is connected to said hydraulic drive means, and a neutral position in which connection between said hydraulic drive means and each of said main oil passage and said return oil passage is disconnected, and

wherein said connection switch means is adapted to connect said main oil passage to said return oil passage in response to an operation of said drive switch means, and also adapted to break the connection between said main oil passage and said return oil passage.

2. The electrohydraulic motor according to claim 1, which further comprises cavitation preventing means connected to a communicating oil passage for passing operation oil through between said drive switch means and said hydraulic drive means, and to said return oil passage, and adapted to supply operation oil from said return oil passage to said communicating oil passage when a pressure of said communicating oil passage is lower than that of said return oil passage.

3. An electrohydraulic motor comprising:

a hydraulic actuator for rotating an output shaft by a pressure of operation oil;

an electric drive motor for rotating a drive shaft according to an inputted electric signal;

a spool valve, connected to said hydraulic actuator, to a main oil passage for leading operation oil supplied from the exterior, and to a return oil passage for leading operation oil to the exterior, for switching connection between said hydraulic actuator and each of said main oil passage and said return oil passage by responding to rotation of said drive shaft;

a first threaded shaft connected to said spool valve;

a second threaded shaft connected to said output shaft and engaged with said first threaded shaft so that said first threaded shaft is perpendicular to said second threaded shaft; and

a separation wall provided in such a manner as to surround said second threaded shaft,

wherein a part of said separation wall, which part is provided at the side of said second threaded shaft, serves as a drain oil passage, and wherein a part of said separation wall, which part is provided at a side opposite to the side of said second threaded shaft, serves as said return oil passage.