Method and device for controlling construction machine

• US 6,108,948 A
• Filed: 11/10/1998
• Issued: 08/29/2000
• Est. Priority Date: 03/10/1997
• Status: Expired due to Fees

• Current Assignee: Caterpillar Sarl (Caterpillar Incorporated)
• Original Assignee: Shin Caterpillar Mitsubishi Ltd. (Caterpillar Incorporated)
• Inventors: Tozawa, Shoji, Ono, Tomoaki
• Primary Examiner(s): PEZZUTO, ROBERT ERIC
• Application Number:
  US09/180,551
• Time in Patent Office: 658 Days
• Field of Search: 37/348, 60/413, 60/414, 60/417, 60/454, 91/511, 172/2, 172/3, 172/4, 172/4.5, 172/7, 172/9, 172/431, 172/435, 701/50
• US Class Current: 37/348
• CPC Class Codes: E02F 3/435 for dipper-arms, backhoes or the like
• CPC Class Codes: E02F 9/2025 Particular purposes of control systems not otherwise provided for E02F3/16, E02F3/26, sub-groups of E02F3/43, E02F3/651, sub-groups of E02F3/84, E02F3/907, E02F5/145 take precedence
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump

Abstract

A control method and apparatus for construction machine. A joint type arm mechanism is provided on a construction machine which is driven by a cylinder type actuator, which is itself connected to a fluid pressure circuit having a pump. The cylinder type actuator'"'"'s delivery pressure is variable in response to the movement of an operation member and is operated by the delivery pressure from the pump. The delivery pressure of the pump is maintained greater than or equal to a predetermined value even when the operation member is in a neutral position for the cylinder type actuator, so that, even immediately after the movement of the arm mechanism is initiated, a response delay of the pump or an increase of the dead zone can be suppressed and the accuracy of the completed movement of a working member can be enhanced.

Claims

1. A control method for a construction machine including (i) a joint type arm mechanism, (ii) a cylinder type actuator being operatively connected to a hydraulic circuit to drive the joint type arm mechanism, and (iii) a pump disposed in the hydraulic circuit and operable to vary delivery pressure in response to a request of an operator via an operation member, the cylinder type actuator being operable to actuate the joint type arm machine and driven by using the delivery pressure of the pump, said method comprising:

(a) detecting whether the operation member is set at a neutral position in which a driving force of the pump is no longer transmitted to the cylinder type actuator;

(b) triggering, in response to a request, of the operator, a control signal to vary the delivery pressure of the pump;

(c) monitoring a current value of loading at the cylinder type actuator; and

(d) maintaining, if the operation member is set in said neutral position as the result of said detecting and in respond to said triggering, the delivery pressure of the pump at a level equal to or higher than at least one reference pressure value selected from various reference pressure values, in accordance with said monitored value of loading at the cylinder type actuator.

2. A control apparatus for a construction machine including (i) a construction main body, (ii) a joint type arm mechanism pivotally connected at one end to the construction machine body and having a working member at the other end portion, (iii) a cylinder type actuator mechanism, operatively connected with the joint type arm mechanism, for actuating the joint type arm mechanism extending and shrinking action of the actuator, (iv) an operation member, to be operated by the operator for operating the joint type arm mechanism via cylinder type actuator mechanism, (v) a hydraulic circuit having a pump being operable to vary delivery pressure to extend and shrink the cylinder type actuator upon receipt a request of the operator via the operation member, said control apparatus comprising:

(a) a detecting device for detecting whether the operation member is set at a neutral position in which a driving force of the pump is no longer transmitted to the cylinder type actuator;

(b) a triggering device for triggering, in response to a request of the operator, a control signal to vary the delivery pressure of the pump;

(c) a monitoring device for monitoring a current value of loading at the cylinder type actuator; and

(d) a pump control device, operable if the operation member is set in said neutral position as the result of detection by said detecting device and responsive to the triggering by said triggering device, for maintaining the pressure value of said pump equal to or higher than at least one reference pressure value selected from various reference pressure values, in accordance with said current value of loading monitored at said monitoring device.

3. A control apparatus for a construction machine as set forth in claim 2, wherein said pump control device includes a storage device for storing various reference pressure values from which said at least one reference pressure value is to be selected by said pump control device.