US 2017/0370382 A1Published application

Hydraulic drive system

AssigneeKawasaki Jukogyo Kabushiki Kaisha

InventorsAkihiro KONDO, Makoto ITO

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Abstract

A hydraulic drive system includes control valve and operating devices, a variable displacement pump, and a flow regulator. When an operating lever inclination angle becomes a value, a control valve opening area becomes a reference. When the operating lever inclination angle maximizes, the opening area maximizes. The flow regulator: until the operating lever inclination angle becomes the value, increases the pump discharge flow rate with the inclination angle, so a differential pressure between pump discharge and actuator load pressures is constant; when the operating lever inclination angle becomes the value, controls the pump discharge flow rate, so a control valve passing flow rate is an actuator maximum flow rate when the differential pressure is constant; and when the operating lever inclination angle is between the value and the maximum, defines a maximum pump discharge flow rate, so the pump discharge flow rate is kept to the actuator maximum flow rate.

Claims10

Dependent claims

A hydraulic drive system comprising:

a control valve device including a control valve that controls supply and discharge of a hydraulic oil to and from an actuator;
an operating device including an operating lever, the operating device moving the control valve device;
a variable displacement pump connected to the control valve by a supply line;
and
a flow regulator that controls a discharge flow rate of the pump, wherein
the control valve device is configured such that when an inclination angle of the operating lever becomes a predetermined value approximating a maximum value, an opening area of the control valve becomes a reference opening area, and when the inclination angle of the operating lever increases from the predetermined value to the maximum value, the opening area increases from the reference opening area to a maximum opening area, and
the flow regulator:
until the inclination angle of the operating lever becomes the predetermined value, increases the discharge flow rate of the pump in accordance with the inclination angle of the operating lever, such that a differential pressure between a discharge pressure of the pump and a load pressure of the actuator is constant;
when the inclination angle of the operating lever becomes the predetermined value, controls the discharge flow rate of the pump, such that a passing flow rate of the control valve is an actuator maximum flow rate in a case where the differential pressure is constant;
and
when the inclination angle of the operating lever is between the predetermined value and the maximum value, defines a maximum discharge flow rate of the pump, such that the discharge flow rate of the pump is kept to the actuator maximum flow rate.

8 more elements

A hydraulic drive system comprising:

a first control valve device including a first control valve that controls supply and discharge of a hydraulic oil to and from a first actuator;
a second control valve device including a second control valve that controls supply and discharge of the hydraulic oil to and from a second actuator;
a first operating device including an operating lever, the first operating device moving the first control valve device;
a second operating device including an operating lever, the second operating device moving the second control valve device;
a variable displacement pump connected to the first control valve and the second control valve by a supply line;
a flow regulator that controls a discharge flow rate of the pump;
a solenoid proportional valve that outputs a secondary pressure to the flow regulator;
and
a controller that controls the solenoid proportional valve, wherein
each of the first control valve device and the second control valve device includes solenoid units each being configured to change a pilot pressure intended for moving the control valve in accordance with an electrical signal fed from the controller, and each control valve device is configured such that, in a case where the corresponding operating device is operated singly, when an inclination angle of the operating lever of the operating device becomes a predetermined value approximating a maximum value, an opening area of the control valve of the control valve device becomes a reference opening area, and when the inclination angle of the operating lever increases from the predetermined value to the maximum value, the opening area increases from the reference opening area to a maximum opening area,
each of the first operating device and the second operating device is an electrical joystick that outputs an electrical signal whose magnitude corresponds to the inclination angle of the operating lever to the controller,
the flow regulator:
until the inclination angle of the operating lever of one of the first operating device and the second operating device, the one operating device corresponding to an actuator with a load higher than that of the other actuator, becomes the predetermined value, increases the discharge flow rate of the pump in accordance with the inclination angle of the operating lever, such that a differential pressure between a discharge pressure of the pump and a load pressure of the actuator corresponding to the one operating device is constant;
and
when the inclination angle of the operating lever of the one operating device becomes the predetermined value, controls the discharge flow rate of the pump, such that a passing flow rate of the corresponding control valve is an actuator maximum flow rate in a case where the differential pressure is constant, and
the controller:
when the inclination angle of the operating lever of the first operating device is between the predetermined value and the maximum value and the inclination angle of the operating lever of the second operating device is between zero and the predetermined value, feeds an electrical signal to one of the solenoid units of the first control valve device, the electrical signal causing the opening area of the first control valve to be the reference opening area, and feeds an electrical signal corresponding to the inclination angle of the operating lever of the second operating device to one of the solenoid units of the second control valve device;
and
when the inclination angle of the operating lever of the second operating device is between the predetermined value and the maximum value and the inclination angle of the operating lever of the first operating device is between zero and the predetermined value, feeds an electrical signal to one of the solenoid units of the second control valve device, the electrical signal causing the opening area of the second control valve to be the reference opening area, and feeds an electrical signal corresponding to the inclination angle of the operating lever of the first operating device to one of the solenoid units of the first control valve device.

16 more elements

A hydraulic drive system comprising:

a first control valve device including a first control valve that controls supply and discharge of a hydraulic oil to and from a first actuator;
a second control valve device including a second control valve that controls supply and discharge of the hydraulic oil to and from a second actuator;
a first operating device including an operating lever, the first operating device moving the first control valve device;
a second operating device including an operating lever, the second operating device moving the second control valve device;
a variable displacement pump connected to the first control valve and the second control valve by a supply line;
a flow regulator that controls a discharge flow rate of the pump;
a solenoid proportional valve that outputs a secondary pressure to the flow regulator;
and
a controller that controls the solenoid proportional valve, wherein
each of the first control valve device and the second control valve device includes solenoid units each being configured to change a pilot pressure intended for moving the control valve in accordance with an electrical signal fed from the controller, and each control valve device is configured such that, in a case where the corresponding operating device is operated singly, when an inclination angle of the operating lever of the operating device becomes a predetermined value approximating a maximum value, an opening area of the control valve of the control valve device becomes a reference opening area, and when the inclination angle of the operating lever increases from the predetermined value to the maximum value, the opening area increases from the reference opening area to a maximum opening area,
each of the first operating device and the second operating device is an electrical joystick that outputs an electrical signal whose magnitude corresponds to the inclination angle of the operating lever to the controller,
the flow regulator:
until the inclination angle of the operating lever of one of the first operating device and the second operating device, the one operating device corresponding to an actuator with a load higher than that of the other actuator, becomes the predetermined value, increases the discharge flow rate of the pump in accordance with the inclination angle of the operating lever, such that a differential pressure between a discharge pressure of the pump and a load pressure of the actuator corresponding to the one operating device is constant;
and
when the inclination angle of the operating lever of the one operating device becomes the predetermined value, controls the discharge flow rate of the pump, such that a passing flow rate of the corresponding control valve is an actuator maximum flow rate in a case where the differential pressure is constant, and
the controller:
when the inclination angle of the operating lever of the first operating device is between the predetermined value and the maximum value and the inclination angle of the operating lever of the second operating device is between zero and the predetermined value, feeds an electrical signal corresponding to the inclination angle of the operating lever of the first operating device to one of the solenoid units of the first control valve device, and feeds an electrical signal that has been corrected in accordance with the inclination angle of the operating lever of the second operating device to one of the solenoid units of the second control valve device;
and
when the inclination angle of the operating lever of the second operating device is between the predetermined value and the maximum value and the inclination angle of the operating lever of the first operating device is between zero and the predetermined value, feeds an electrical signal corresponding to the inclination angle of the operating lever of the second operating device to one of the solenoid units of the second control valve device, and feeds an electrical signal that has been corrected in accordance with the inclination angle of the operating lever of the first operating device to one of the solenoid units of the first control valve device.

16 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/543,873Filed 9 Dec 2016
Priority: JP 2015-24076210 Dec 2015
Published: 28 Dec 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification29 codes

F15B 11/166
With sensing of servomotor demand or load: controlling a pilot pressure in response to the load, i.e. supply to at least one user is regulated by…
E02F 9/2004
Drives; Control devices: control mechanisms, e.g. control levers
E02F 9/2232
Control of flow rate; Load sensing arrangements: using one or more variable displacement pumps
E02F 9/2285
Hydraulic circuits: pilot-operated systems

Family

US 10,260,531 B2Related patent
US 2017/0370382 A1This patent

From the US filing history. Foreign family members aren’t listed.

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