Construction machine

Patent metadata

Field	Value
Publication number	US-11499296-B2
Application number	US-202017417812-A
Country	US
Kind code	B2
Filing date	Feb 12, 2020
Priority date	Feb 28, 2019
Publication date	Nov 15, 2022
Grant date	Nov 15, 2022

Abstract

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller (51) controls a cap-side selector valve (46) and a rod-side selector valve (47) such that a particular open-circuit pump (15) not connected to a single rod hydraulic cylinder (3) is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve (49) provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor (7) are driven simultaneously.

First claim

The invention claimed is:

1. A construction machine, comprising:
a tank that stores hydraulic operating fluid;
a plurality of closed-circuit pumps including bidirectionally-tiltable hydraulic pumps;
a plurality of open-circuit pumps including unidirectionally-tiltable hydraulic pumps, the number of the unidirectionally-tiltable hydraulic pumps being same as the number of the plurality of closed-circuit pumps;
a plurality of hydraulic actuators including at least one single rod hydraulic cylinder, and at least one hydraulic motor;
an operation device for giving an instruction about operation of the plurality of hydraulic actuators;
a plurality of closed-circuit selector valves that connect the plurality of closed-circuit pumps to the plurality of hydraulic actuators such that closed circuits are formed;
a plurality of cap-side selector valves that connect delivery ports of the plurality of open-circuit pumps to a cap chamber of the single rod hydraulic cylinder;
a plurality of proportional valves that are provided on flow lines that connect the delivery ports of the plurality of open-circuit pumps to the tank;
a cap pressure sensor that senses a pressure in the cap chamber;
a rod pressure sensor that senses a pressure in a rod chamber of the single rod hydraulic cylinder;
a controller that controls the plurality of closed-circuit selector valves and the plurality of cap-side selector valves, and controls a delivery flow rate of each of the plurality of closed-circuit pumps and the plurality of open-circuit pumps, and opening areas of the plurality of proportional valves, on a basis of inputs from the operation device, the cap pressure sensor, and the rod pressure sensor; and
a plurality of rod-side selector valves that connect the delivery ports of the plurality of open-circuit pumps to the rod chamber,
a cap-side discharge flow line that connects the cap chamber to the tank; and
a meter-out valve provided on the cap-side discharge flow line,
wherein the controller is configured to, in a case where the single rod hydraulic cylinder and the hydraulic motor are driven simultaneously,
control the plurality of cap-side selector valves and the plurality of rod-side selector valves such that a particular open-circuit pump in the plurality of open-circuit pumps that is not connected to the single rod hydraulic cylinder gets connected with the single rod hydraulic cylinder, and
control an opening area of a particular proportional valve provided on a flow line that connects a delivery port of the particular open-circuit pump to the tank;

wherein the controller is configured to, in a case where the hydraulic motor is driven at a same time that the single rod hydraulic cylinder is operated toward a contraction side,
control the plurality of cap-side selector valves and the plurality of rod-side selector valves such that the particular open-circuit pump is connected to the rod chamber, close the particular proportional valve, and open the meter-out valve;
wherein the construction machine further comprises:
a charge pump;
a charge line connected to a delivery port of the charge pump;
a charge relief valve provided on the charge line; and
a charge pressure sensor that senses a pressure in the charge line,
wherein the controller is further configured to, in a case where the hydraulic motor is driven at a same time that the single rod hydraulic cylinder is driven toward the contraction side in a state where the pressure in the cap chamber is higher than the pressure in the rod chamber,
control the plurality of cap-side selector valves and the plurality of rod-side selector valves such that the particular open-circuit pump gets connected to the rod chamber,
close the particular proportional valve,
open the meter-out valve, and
reduce an opening area of the meter-out valve when the pressure in the charge line falls below a predetermined pressure set lower than a set pressure of the charge relief valve.

2. A construction machine, comprising:
a tank that stores hydraulic operating fluid;
a plurality of closed-circuit pumps including bidirectionally-tiltable hydraulic pumps;
a plurality of open-circuit pumps including unidirectionally-tiltable hydraulic pumps, the number of the unidirectionally-tiltable hydraulic pumps being same as the number of the plurality of closed-circuit pumps;
a plurality of hydraulic actuators including at least one single rod hydraulic cylinder, and at least one hydraulic motor;
an operation device for giving an instruction about operation of the plurality of hydraulic actuators;
a plurality of closed-circuit selector valves that connect the plurality of closed-circuit pumps to the plurality of hydraulic actuators such that closed circuits are formed;
a plurality of cap-side selector valves that connect delivery ports of the plurality of open-circuit pumps to a cap chamber of the single rod hydraulic cylinder;
a plurality of proportional valves that are provided on flow lines that connect the delivery ports of the plurality of open-circuit pumps to the tank;
a cap pressure sensor that senses a pressure in the cap chamber;
a rod pressure sensor that senses a pressure in a rod chamber of the single rod hydraulic cylinder;
a controller that controls the plurality of closed-circuit selector valves and the plurality of cap-side selector valves, and controls a delivery flow rate of each of the plurality of closed-circuit pumps and the plurality of open-circuit pumps, and opening areas of the plurality of proportional valves, on a basis of inputs from the operation device, the cap pressure sensor, and the rod pressure sensor; and
a plurality of rod-side selector valves that connect the delivery ports of the plurality of open-circuit pumps to the rod chamber,
a cap-side discharge flow line that connects the cap chamber to the tank; and
a meter-out valve provided on the cap-side discharge flow line,
wherein the controller is configured to, in a case where the single rod hydraulic cylinder and the hydraulic motor are driven simultaneously,
control the plurality of cap-side selector valves and the plurality of rod-side selector valves such that a particular open-circuit pump in the plurality of open-circuit pumps that is not connected to the single rod hydraulic cylinder gets connected with the single rod hydraulic cylinder, and
control an opening area of a particular proportional valve provided on a flow line that connects a delivery port of the particular open-circuit pump to the tank;

wherein the controller is configured to, in a case where the hydraulic motor is driven at a same time that the single rod hydraulic cylinder is operated toward a contraction side,
control the plurality of cap-side selector valves and the plurality of rod-side selector valves such that the particular open-circuit pump is connected to the rod chamber, close the particular proportional valve, and open the meter-out valve;
wherein the construction machine further comprises:
a charge pump;
a charge line connected to a delivery port of the charge pump;
a charge relief valve provided on the charge line; and
a charge pressure sensor that senses a pressure in the charge line,
wherein the controller is further configured to, in a case where the hydraulic motor is driven at a same time that the single rod hydraulic cylinder is driven toward the contraction side in a state where the pressure in the cap chamber is higher than the pressure in the rod chamber,
control the plurality of cap-side selector valves and the plurality of rod-side selector valves such that the particular open-circuit pump gets connected to the rod chamber,
close the particular proportional valve,
open the meter-out valve, and
increase a delivery flow rate of the particular open-circuit pump in a case where the pressure in the charge line falls below a predetermi

Assignees

• Hitachi Construction Mach Co

Inventors

• KAI Takamasa
• Shimizu Juri
• Hiraku Kenji
• Takahashi Hiromasa
• Saitou Teppei

Classifications

• F15B2211/7135

  Combinations of output members of different types, e.g. single-acting cylinders with rotary motors · CPC title

• F15B13/024

  Pressure relief valves · CPC title

• F15B2211/426

  electrically or electronically · CPC title

• F15B2211/20576

  with multiple pumps · CPC title

• F15B13/0416

  with means or adapted for load sensing · CPC title