Kabushiki Kaisha Toyota Jidoshokki

Nishina Industrial Co., Ltd.

Tsutomu Matsuo

Yuki Ueda

Takashi Uno

Naoya Yokomachi

Hirohiko Ishikawa

Tetsuya Goto

Junichi Morita

Toshinari Fukatsu

Takanori Kanna

Ryo Yazawa

Akira Nakajo

A hydraulic drive device for an industrial vehicle includes a variable displacement pump, a displacement control valve, a power steering cylinder, a power steering valve, a loading cylinder, a loading valve, a hydraulic oil passage, and a pilot line. The displacement control valve controls the variable displacement pump to increase displacement of the variable displacement pump when differential pressure between discharge pressure of hydraulic oil discharged from the variable displacement pump and pilot pressure generated in the pilot line is smaller than a predetermined set pressure. A spool of the loading valve is provided with a groove portion that forms a communication passage that makes communication between the hydraulic oil passage and the pilot line at a neutral position of the loading valve when the power steering valve is located in a neutral position.

Hydraulic drive device for industrial vehicle

Provided is a variable displacement pump which sucks and discharges a working fluid by moving a piston with a stroke in response to an inclination angle of a swash plate, the variable displacement pump including: a control piston which includes a columnar piston portion pressing the swash plate and adjusts the inclination angle of the swash plate between a maximal inclination angle in which a discharge capacity of the working fluid becomes maximal and a minimal inclination angle in which the discharge capacity of the working fluid becomes minimal; a piston accommodation portion which is formed in the housing and accommodates the piston portion; and a pressed portion which is disposed between the swash plate and the piston portion and is pressed toward the swash plate by the piston portion, in which when the inclination angle of the swash plate is an intermediate inclination angle in which the discharge capacity of the working fluid becomes an intermediate amount between the maximal amount and the minimal amount, a contact point between the piston portion and the pressed portion is located at a center portion including an axis center of the piston portion in an end surface on the side of the swash plate in the piston portion.

Variable displacement pump

A variable displacement swash plate type piston pump includes first and second housing members fastened to each other by fastening members, a rotary shaft, a swash plate. A section of the inner circumferential surface of the first housing member has a recess. A bulging portion is arranged in a section of the outer circumferential wall of the first housing member. A section of the outer circumferential wall of the second housing member has a closing portion that closes the opening of the recess. The fastening members include first and second fastening members arranged at positions that are on the opposite sides of the recess, inside the width of the swash plate in a direction along the inclination axis of the swash plate, and closer to the rotary shaft than the distal ends of the bulging portion and the closing portion in the bulging direction.

Variable displacement swash plate type piston pump

Provided is a variable displacement pump which includes a cylinder block including a plurality of cylinder bores formed in a rotation shaft in a circumferential direction and rotating together with the rotation shaft, a piston provided inside each of the plurality of cylinder bores to be slidable, and a swash plate supported to be tiltable with respect to the rotation shaft while a distal end portion of the piston is slidable thereon and which sucks and discharges a working fluid by moving the piston in a reciprocating manner with a stroke in accordance with an inclination angle of the swash plate, the variable displacement pump including: a control piston which includes a piston portion pressing the swash plate and controls the inclination angle of the swash plate; a piston accommodation portion which is formed in the housing and accommodates the piston portion; and a hollow cylindrical guide portion which is disposed between the piston accommodation portion and the piston portion and includes an inner peripheral surface supporting the piston portion to be slidable thereon, in which the housing is formed of a material having higher fatigue strength than the guide portion and the guide portion is formed of a material harder than the housing.

A hydraulic control device of a forklift truck includes a first hydraulic cylinder, a first instructing member, a second hydraulic cylinder, a second instructing member, a hydraulic pump, an electric motor, a first oil passage, a lowering control valve, a second oil passage that is branched from the first oil passage at a junction, a flow control valve, a first pilot passage through which pressure in the first oil passage at a position between the first hydraulic cylinder and the lowering control valve is applied to a first accommodating chamber of the flow control valve as the pressure upstream of the lowering control valve, and a second pilot passage through which pressure in the first oil passage at a position between the lowering control valve and the hydraulic pump is applied to a second accommodating chamber of the flow control valve as the pressure downstream of the lowering control valve.

Hydraulic control device of forklift truck

A hydraulic pump having a rotary shaft rotatably supported with respect to a casing, the hydraulic pump including: a bearing part provided to one end side and the other end side of the rotary shaft; and a first annular member provided around the rotary shaft on at least one side of the one end side and the other end side of the rotary shaft. The bearing part on the one side has a support part which rotatably supports the rotary shaft, and a preload applying member which applies a preload in the axial direction to the support part. The first annular member is interposed between the bearing part of the one side and a receiving part of the rotary shaft in the axial direction, and an inner diameter of the first annular member is larger than a diameter of the rotary shaft.

Hydraulic pump

A hydraulic control device of a forklift truck includes a first hydraulic cylinder, a first instruction member, a second hydraulic cylinder, a second instruction member, a hydraulic pump, an electric motor, a first passage which has a drain passage, a lowering control valve that controls flow of hydraulic oil, a flow rate control valve, and a controller. When a lowering operation of forks and an operation of a hydraulically-operated unit are performed simultaneously, when a required rotation speed of the hydraulic pump that is required for operating the hydraulically-operated unit at an instruction speed based on an operation of the second instruction member is a specified rotation speed or lower, the controller controls an instruction rotation speed of the electric motor so as to operate the hydraulic pump at the required rotation speed to thereby restrict the operation of the hydraulic pump.

Hydraulic control device of a forklift truck

A hydraulic control device for a forklift includes: a plurality of hydraulic mechanisms including a lifting/lowering hydraulic cylinder and a tilting hydraulic cylinder; a hydraulic pump; an electric motor; a discharge control mechanism; a proportional valve; a flow rate control valve; and a controller. When the lifting/lowering hydraulic cylinder performs a lowering operation of the fork and a hydraulic mechanism other than the lifting/lowering hydraulic cylinder simultaneously performs a further operation, the controller controls an open degree of the proportional valve in accordance with a rotation speed difference of a required lowering operation rotation speed for the hydraulic pump, which is required to perform the lowering operation at an instructed speed that is in accordance with an operation amount of the lifting/lowering control member, and a required further operation rotation speed for the hydraulic pump, which is required to perform the further operation.

Hydraulic control device for forklift

An electromagnetic switching valve, for which the maximum opening is set to be small, is disposed on piping between a lift cylinder and a hydraulic pump motor. A pilot check valve, for which the maximum opening is set to be larger than the electromagnetic switching valve, is disposed on piping, different from the piping, between the lift cylinder and the hydraulic pump motor. In addition, during lowering operations, first, the electromagnetic switching valve is opened, and then after the same is opened, the pilot check valve is opened after a prescribed time has passed. Thus, the shock generated when lowering an object to be raised/lowered is reduced and a fork is operated quickly.

Lifting device

A hydraulic control device for a forklift includes a hydraulic pump, a single electric motor for driving the hydraulic pump, an outflow control mechanism provided between a lift cylinder and the hydraulic pump, a flow control valve provided between the outflow control mechanism and a draining portion, and a controller. When a lowering operation of a fork and either forward or rearward mast tilting operations of a mast are performed at the same time, the controller controls the electric motor based on a target speed of the hydraulic pump. The flow control valve controls the flow rate of hydraulic fluid from the lift cylinder to the hydraulic pump and the flow rate from the lift cylinder to the draining portion in accordance with the difference between the actual rotation speed of the hydraulic pump and the target rotation speed of the hydraulic pump.

An outlet port of a hydraulic pump/motor and a bottom chamber of a lift cylinder are connected to each other by a hydraulic fluid passage. A hydraulic fluid passage that is connected to a hydraulic fluid tank is formed to branch off the hydraulic fluid passage. A flow control valve controls the hydraulic fluid delivered from the lift cylinder when the fork is lowered, thereby regulating the flow rate of hydraulic fluid supplied to the hydraulic pump/motor and the flow rate of hydraulic fluid supplied to the hydraulic fluid tank. If regenerative operation can be performed, the flow control valve is closed and hydraulic fluid is delivered to the hydraulic pump/motor. If regenerative operation cannot be performed, the flow control valve is opened and hydraulic fluid is delivered to the hydraulic fluid tank. In either case, the fork can be lowered at an instructed speed.

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Kariya, Japan

Tsutomu Matsuo