Kawasaki Jukogyo Kabushiki Kaisha

Akihiro Kondo

Hideyasu Muraoka

Yoshiyuki Tode

Naoki Hata

Makoto Ito

Nobuyuki Kinoshita

Hiroaki Mitsui

Kazuto Fujiyama

Takehisa Kato

Yoji Yudate

Toshihisa Toyota

Jun Umekawa

Koki Mibu

Hiroaki Shimizu

Kazuya Iwabe

Yuki Nakayama

Takashi Nakatsuji

Ryosuke Kusumoto

Hitoshi Nakagawa

Yousuke Kataoka

Hideki Tanaka

Hiroaki Fujimoto

Seiji Aoki

Moriyuki Sakamoto

Makoto Itoh

Akihito Suzuki

Haruo Yamada

Shinya Sasaki

Takuya Fukumoto

A hydraulic pump performance deterioration detection system according to one embodiment includes: a variable displacement hydraulic pump; a switching valve that is connected to the hydraulic pump by a pump line and to a hydraulic actuator by a supply/discharge line; and a regulator that changes a displacement of the hydraulic pump in accordance with a command current and that limits the displacement of the hydraulic pump to a limiting value when a delivery pressure of the hydraulic pump has become higher than a setting value. The performance deterioration detection system further includes: control circuitry that feeds the command current to the regulator; and a pressure sensor that measures the delivery pressure of the hydraulic pump. When the hydraulic actuator is not moving, the control circuitry determines whether or not performance of the hydraulic pump has deteriorated based on a current value of the command current and the delivery pressure of the hydraulic pump measured by the pressure sensor.

Hydraulic pump performance deterioration detection system

A hydraulic pump performance deterioration detection system according to one embodiment includes: a hydraulic pump that is driven by a prime mover and that supplies a hydraulic liquid to a hydraulic actuator to move the hydraulic actuator; a switching valve located on a passage through which the hydraulic liquid delivered from the hydraulic pump flows, the switching valve being switchable between an open position and a closed position; and control circuitry configured to change a rotation speed of the prime mover. When the hydraulic actuator is not moving, in a state where the switching valve is switched to the closed position, the control circuitry determines whether or not performance of the hydraulic pump has deteriorated based on the rotation speed of the prime mover and a delivery pressure of the hydraulic pump measured by a pressure sensor.

A hydraulic pump performance deterioration detection system according to one embodiment includes: a variable displacement hydraulic pump that supplies a hydraulic liquid to a hydraulic actuator to move the hydraulic actuator; a regulator that changes a displacement of the hydraulic pump in accordance with a command current; and control circuitry that feeds the command current to the regulator. When the hydraulic actuator is not moving, in a state where a switching valve located on a passage through which the hydraulic liquid delivered from the hydraulic pump flows is switched to a closed position and the hydraulic pump is being driven at a predetermined rotation speed, the control circuitry determines whether or not performance of the hydraulic pump has deteriorated based on a current value of the command current and a delivery pressure of the hydraulic pump measured by a pressure sensor.

A directional and flow control valve includes: a housing with a pump port, a first supply/discharge port, a second supply/discharge port, and a tank port, the housing including therein a first pilot chamber, a second pilot chamber, and a third pilot chamber; and a first spool and a second spool, which are independent of each other. The first spool includes a first end surface facing the first pilot chamber and a second end surface facing the third pilot chamber. The second spool includes a first end surface facing the second pilot chamber and a second end surface facing the third pilot chamber. The first spool brings the first supply/discharge port into one of the pump port or the tank port, and the second spool brings the second supply/discharge port into the other one of the pump port or the tank port.

Directional and flow control valve and hydraulic system

This hydraulic pump system includes: a hydraulic pump having a discharge flow rate that is changeable; a regulator device that adjusts the discharge flow rate of the hydraulic pump; an operation device including an operation tool; a lock switching input unit that unlocks the operation tool; an unloader valve that adjusts a discharge pressure of the hydraulic pump by changing the opening area of the unloader valve; and a control device that controls movement of the unloader valve. When a predetermined actuation condition is satisfied, the control device causes the unloader valve to reduce the opening area to increase the discharge pressure of the hydraulic pump. The regulator device increases the discharge flow rate after the control device causes an increase in the discharge pressure of the hydraulic pump. The actuation condition includes a condition that the lock switching input unit has unlocked the operation tool.

Hydraulic pump system and control device

A multi-control valve unit includes a housing with built-in spools that are parallel to each other. The housing includes pilot chambers formed therein, the pilot chambers corresponding to both ends of the spools. Solenoid proportional valves are mounted to the housing, such that the solenoid proportional valves are connected to the respective pilot chambers. A hydraulic pressure generator is mounted to the housing, such that the hydraulic pressure generator is connected to the solenoid proportional valves. The hydraulic pressure generator includes an electric motor and a pump.

Multi-control valve unit

A hydraulic excavator drive system includes: a first pump connected to a head-side chamber of a boom cylinder; and a second pump that supplies hydraulic oil to one of, or both, an arm cylinder and a bucket cylinder. The first pump is driven by an electric motor. The drive system further includes a switching valve that is in a first position at a boom raising operation and in a second position at a vehicle body lifting operation. The first position is a position in which the switching valve brings a rod-side chamber of the boom cylinder into communication with a tank, and the second position is a position in which the switching valve brings the rod-side chamber into communication with the second pump.

Hydraulic excavator drive system

A hydraulic excavator drive system includes: a first pump that is connected to a head-side chamber of a boom cylinder by a head-side line and to a rod-side chamber of the boom cylinder by a rod-side line to form a closed circuit; and a second pump that supplies hydraulic oil to at least one of an arm cylinder or a bucket cylinder. The hydraulic excavator drive system further includes a switching valve located on a relay line that connects a supply line extending from the second pump to the rod-side line. The switching valve opens the relay line at a boom raising operation and blocks the relay line except at the boom raising operation.

A hydraulic excavator drive system () includes an arm control valve () and an arm switching valve (). The arm switching valve () is connected to an arm pushing supply line () by a rod-side line () and to an arm crowding supply line () by a head-side line (). The arm switching valve () is switched between a neutral position, a recycling position in which the arm switching valve () allows the rod-side line () to communicate with the head-side line () and a second tank line (), and a meter-out control position in which the arm switching valve () allows the head-side line () to communicate with the tank line (). The arm switching valve () incorporates therein a check valve () that allows a flow from the rod-side line () toward the head-side line () when the arm switching valve () is in the recycling position.

A housing of a multi-control valve includes an arm parallel passage, an arm crowding supply passage, an arm pushing supply passage, a boom parallel passage, a boom raising supply passage, and a boom lowering supply passage. The housing further includes: a slide hole; a head-side passage that is branched off from the boom raising supply passage and extends to the slide hole; a rod-side passage that is branched off from the boom lowering supply passage and extends to the slide hole; and a regeneration passage that extends from the slide hole to the arm parallel passage. The slide hole receives a boom sub spool therein. The boom sub spool is either a boom recycling spool or a boom regeneration spool.

Multi-control valve

A HST system for use in traveling of a vehicle includes a controller that controls a pump regulator that changes a displacement of a pump and a motor regulator that changes a displacement of a motor. The controller determines whether or not a particular downhill travel condition is satisfied based on a result of detection by a vehicle speed detector that detects a vehicle speed of the vehicle and a result of detection by a rotation number detector that detects a number of rotations of an engine per unit time. In a case where a depression amount of an accelerator pedal, which is detected by a depression amount detector, is zero and the particular downhill travel condition is satisfied, the controller controls the motor regulator to increase the displacement of the motor.

Hydraulic static transmission system

A hydraulic excavator drive system includes: a first pump connected to a head-side chamber of a boom cylinder; and a second pump that supplies hydraulic oil to at least one of an arm cylinder or a bucket cylinder. The first pump is driven by an electric motor. The drive system further includes: a first switching valve located on a rod-side line; and a second switching valve located on a relay line. The first switching valve opens the rod-side line at a boom raising operation, but blocks the rod-side line except at the boom raising operation. The second switching valve blocks the relay line at the boom raising operation, but opens the relay line at a vehicle body lifting operation.

A hydraulic system includes: a cylinder that moves a moving object in a vertical direction by extension and retraction of a rod; a first bidirectional pump connected to a head-side chamber of the cylinder by a first supply/discharge line; a second bidirectional pump connected to a rod-side chamber of the cylinder by a second supply/discharge line and coupled to the first bidirectional pump in a manner enabling torque to be transmitted between the first and second bidirectional pumps; a relay line connecting the first and second bidirectional pumps such that a hydraulic liquid discharged from one of the first and second bidirectional pumps is introduced into the other of the first and second bidirectional pumps; and a servomotor that drives the first or second bidirectional pump. At least one of the first and second bidirectional pumps is a variable displacement pump whose delivery capacity per rotation is freely variable.

Hydraulic system

A hydraulic system of a construction machine includes: control valves interposed between a main pump and hydraulic actuators; and first solenoid proportional valves connected to pilot ports of the control valves. The hydraulic system further includes: a brake for a slewing motor; and a second solenoid proportional valve connected to a brake release port of the brake by a secondary pressure line and connected to an auxiliary pump by a primary pressure line. A switching valve including a pilot port connected to the secondary pressure line by a pilot line is interposed between the auxiliary pump and the first solenoid proportional valves.

Hydraulic system of construction machine

A hydraulic system includes: a slewing motor; a mechanical brake; and a slewing control valve interposed between a main pump and the slewing motor. A first pilot port of the slewing control valve is connected to a first solenoid proportional valve by a pilot line. A second pilot port of the slewing control valve is connected to a second solenoid proportional valve by a second pilot line. The first solenoid proportional valve and the second solenoid proportional valve are connected to an auxiliary pump by a primary pressure line. A switching valve is interposed between the auxiliary pump and the mechanical brake. The switching valve includes a pilot port that is connected to the first pilot line by a switching pilot line. The valve switches from a closed to an open position when a pilot pressure led to the pilot port becomes higher than or equal to a setting value.

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Kobe, Japan

Akihiro Kondo