Hydraulic system

Patent metadata

Field	Value
Publication number	US-10837473-B2
Application number	US-201716085797-A
Country	US
Kind code	B2
Filing date	Mar 24, 2017
Priority date	Mar 24, 2016
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

This hydraulic system is provided with a hydraulic pump, a control valve, and a pilot pressure supply unit. The pilot pressure supply unit has: an electromagnetic proportional valve that has a detent-type emergency manual operation function with which a pilot oil passage can be opened manually and generates pilot pressure for a control valve; a controller that controls the degree of opening of the electromagnetic proportional valve in accordance with the operation of an operation lever; and a pilot pressure switching unit that switches the oil pressure state of the pilot pressure supply unit between an on-loading state and an unloading state. The pilot pressure switching unit performs control to implement the unloading state when the electromagnetic proportional valve is being opened manually and performs control to implement the on-loading state after the electromagnetic proportional valve has been opened manually.

First claim

The invention claimed is:

1. A hydraulic system comprising: a hydraulic pump; a control valve for supplying an operating pressure from the hydraulic pump to an actuator of a working machine; and a pilot pressure supply unit for supplying a pilot pressure to the control valve, wherein
the pilot pressure supply unit includes:
an electromagnetic proportional valve that has a detent-type emergency manual operation function capable of manually opening a pilot oil passage and generates the pilot pressure to the control valve;
a controller for controlling a degree of opening of the electromagnetic proportional valve in accordance with an operation of an operation lever; and
a pilot pressure switching unit that switches the electromagnetic proportional valve between an on-loading state and an unloading state based on control of the controller or an operation of an operator; and
an emergency operation selection switch that switches a power supply system to the pilot pressure switching unit between a first control system in a normal state and a second control system during an emergency operation based on an operation of the operator.

2. The hydraulic system according to claim 1 , wherein the pilot pressure switching unit includes:
a pilot pressure unloading solenoid valve for switching the electromagnetic proportional valve between the on-loading state and the unloading state; and
an emergency operation activation switch that is provided in the second control system to manually control an energization state of the pilot pressure unloading solenoid valve.

3. The hydraulic system according to claim 2 , wherein the emergency operation activation switch is a momentary type switch.

4. The hydraulic system according to claim 2 , wherein the emergency operation activation switch is disposed in a cab of the working machine.

5. The hydraulic system according to claim 1 , wherein the hydraulic pump makes a supply amount of a working oil during the emergency operation smaller than a supply amount of the working oil in the normal state in accordance with the switching of the emergency operation selection switch.

Assignees

• Tadano Ltd

Inventors

• Kawabuchi Naoto
• Yoshida Naofumi
• Masuda Naotaka
• Fukumori Yasuhiro

Classifications

• B66C13/20 Primary

  for non-electric drives (transmitting control pulses B66C13/40) · CPC title

• F15B20/002 Primary

  Electrical failure · CPC title

• F15B13/043

  with electrically-controlled pilot valves · CPC title

• B66C23/88

  Safety gear (for cranes in general B66C15/00; for rope, cable, or chain winding mechanisms B66D1/54) · CPC title