Construction machine

Patent metadata

Field	Value
Publication number	US-10829908-B2
Application number	US-201716338519-A
Country	US
Kind code	B2
Filing date	Nov 16, 2017
Priority date	Nov 24, 2016
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

This construction machine includes a first hydraulic drive device that is driven by a first prime mover and a second hydraulic drive device that is driven by a second prime mover. The first hydraulic drive device has a first closed circuit that connects a first hydraulic actuator and a first closed-circuit pump and a first assist flow path that connects the first closed circuit and a first open-circuit pump and that supplies pressure oil from the first open-circuit pump to the first closed circuit. The second hydraulic drive device is provided with a second closed circuit that connects a second hydraulic actuator and a second closed-circuit pump. The present invention also includes a first emergency flow path that branches from the first assist flow path and connects to the second closed circuit and that supplies pressure oil from the first open-circuit pump to the second closed circuit.

First claim

The invention claimed is:

1. A construction machine comprising:
a first prime mover;
a first hydraulic drive device that has a first closed-circuit pump and a first open-circuit pump being driven by the first prime mover;
a first hydraulic actuator that operates with pressure oil supplied from at least one of the first closed-circuit pump and the first open-circuit pump;
a second prime mover;
a second hydraulic drive device that has a second closed-circuit pump and a second open-circuit pump being driven by the second prime mover; and
a second hydraulic actuator that operates with pressure oil supplied from at least one of the second closed-circuit pump and the second open-circuit pump, wherein
the first hydraulic drive device has:
a first closed circuit that connects the first hydraulic actuator and the first closed-circuit pump; and
a first assist flow path that connects the first closed circuit and the first open-circuit pump and that supplies pressure oil from the first open-circuit pump to the first closed circuit, the second hydraulic drive device is provided with:
a second closed circuit that connects the second hydraulic actuator and the second closed-circuit pump, and
the construction machine further comprises:
a first emergency flow path that branches from the first assist flow path and connects to the second closed circuit and that supplies pressure oil from the first open-circuit pump to the second closed circuit;
a first assist switching device for guiding pressure oil flowing through the first assist flow path to the first emergency flow path; and
a control device that controls operation of the first assist switching device; and
if the second prime mover is inoperative, the control device switches the first assist switching device to supply pressure oil from the first open-circuit pump to the second closed circuit through the first emergency flow path to operate the second hydraulic actuator and to operate the first hydraulic actuator with pressure oil supplied from the first closed-circuit pump.

2. The construction machine according to claim 1 , wherein
the second hydraulic drive device has:
a second assist flow path that connects the second closed circuit and the second open-circuit pump and that supplies pressure oil from the second open-circuit pump to the second closed circuit,
the construction machine further comprises:
a second emergency flow path that branches from the second assist flow path and connects to the first closed circuit and that supplies pressure oil from the second open-circuit pump to the first closed circuit; and
a second assist switching device for guiding pressure oil flowing through the second assist flow path to the second emergency flow path, and
the control device controls operation of the second assist switching device.

3. The construction machine according to claim 2 , further comprising:
a first emergency closed circuit that connects the second hydraulic actuator and the first closed-circuit pump and that circulates pressure oil between the second hydraulic actuator and the first closed-circuit pump;
a first closed-circuit switching device for guiding, to the first emergency closed circuit, the pressure oil supplied from the first closed-circuit pump and flowing through the first closed circuit;
a second emergency closed circuit that connects the first hydraulic actuator and the second closed-circuit pump and that circulates pressure oil between the first hydraulic actuator and the second closed-circuit pump; and
a second closed-circuit switching device for guiding, to the second emergency closed circuit, the pressure oil supplied from the second closed-circuit pump and flowing through the second closed circuit, wherein the control device controls operations of the first closed-circuit switching device and the second closed-circuit switching device.

4. The construction machine according to claim 3 , wherein
the control device includes an engine failure detection section that detects a failure in the first prime mover and the second prime mover,
if it is detected by the engine failure detection section that the second prime mover is inoperative,
the control device controls the operation of the first assist switching device to perform switching such that the pressure oil flowing through the first assist flow path is guided to the first emergency flow path, and also controls the operation of the first closed-circuit switching device to perform switching such that the pressure oil supplied from the first closed-circuit pump and flowing through the first closed circuit is guided to the first emergency closed circuit, so that the pressure oil is supplied to the first hydraulic actuator and the second hydraulic actuator by the first closed-circuit pump and the first open-circuit pump, and the operations of the hydraulic actuators are enabled, and
if it is detected by the engine failure detection section that the first prime mover is inoperative,
the control device controls the operation of the second assist switching device to perform switching such that the pressure oil flowing through the second assist flow path is guided to the second emergency flow path, and also controls the operation of the second closed-circuit switching device to perform switching such that the pressure oil supplied from the second closed-circuit pump and flowing through the second closed circuit is guided to the second emergency closed circuit, so that the pressure oil is supplied to the first hydraulic actuator and the second hydraulic actuator by the second closed-circuit pump and the second open-circuit pump, and the operations of the hydraulic actuators are enabled.

5. The construction machine according to claim 4 , further comprising:
a hydraulic oil tank that stores hydraulic oil;
a first hydraulic oil return flow path that returns, to the hydraulic oil tank, the pressure oil supplied from the first open-circuit pump to the second hydraulic actuator through the first emergency flow path; and
a second hydraulic oil return flow path that returns, to the hydraulic oil tank, the pressure oil supplied from the second open-circuit pump to the first hydraulic actuator through the second emergency flow path.

6. The construction machine according to claim 5 , further comprising:
a travel base;
a hydraulic motor that drives the travel base;
an upperstructure that is turnably disposed on the travel base; and
a working device that has a boom, a boom cylinder for driving the boom, an arm, an arm cylinder for driving the arm, a bucket, and a bucket cylinder for driving the bucket, wherein
a plurality of first hydraulic actuators include the boom cylinder and the arm cylinder,
a plurality of second hydraulic actuators include the bucket cylinder and the hydraulic motor, and
if it is detected by the engine failure detection section that the second prime mover is inoperative, the control device controls the operations of the first assist switching device and the first closed-circuit switching device so that the boom cylinder and the hydraulic motor are operated by a plurality of first closed-circuit pumps and the arm cylinder and the bucket cylinder are operated by a plurality of first open-circuit pumps.

7. The construction machine according to claim 6 , further comprising an operating device for operating the working device, wherein
the control device controls the operations of the first assist switching device, the second assist switching device, the first closed-circuit switching device, and the second closed-circuit switching device in accordance with manipulated variables of the operating device.

Assignees

• Hitachi Construction Mach Co

Inventors

• SAITOH Teppei
• Hiraku Kenji
• Shimizu Juri
• Takahashi Hiromasa

Classifications

• F15B20/00 Primary

  Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems · CPC title

• E02F9/22

  Hydraulic or pneumatic drives {(for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22)} · CPC title

• E02F9/2242 Primary

  including an electronic controller · CPC title

• F15B2211/86

  Control during or prevention of abnormal conditions · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title