Kabushiki Kaisha Toyoda Jidoshokki Seisakusho

Other

Kabushiki Kaisha Toyota Chuo Kenkyusho

Katsumi Nagai

Teruyuki Nishimyou

Masataka Osawa

Yasunobu Yagita

Hitoshi Ban

Takaki Ogawa

Yasuhiko Naruse

An industrial vehicle has a loading attachment, a mast, a tilt cylinder, first and second pressure sensors and a controller. The mast supports the attachment and guides the attachment. The tilt cylinder has a piston and a piston rod and operates by hydraulic fluid from a hydraulic fluid source. The piston rod connects with the piston and also connects with the mast. The piston divides the inside of the tilt cylinder into a rod side chamber and a bottom side chamber. The first and second pressure sensors respectively detect pressures of the hydraulic fluid in the rod side and the bottom side chambers. The controller calculates an axial force applied to the tilt cylinder based on signals detected by the sensors and calculates load weight moment in a back and forth direction of the vehicle based on the axial force and compares the calculated moment with a predetermined value.

Industrial vehicle with a device for measuring load weight moment and a method therefor

A pressure sensor is set in a conduit connected to a cylinder tube, and a temperature sensor is disposed within a chamber. Detection signals of the pressure sensor and the temperature sensor are sent to a control circuit. A sonic speed of the ultrasonic wave is corrected by using a relational formula or a map that is indicative of the relationship of the temperature and pressure of hydraulic oil to the sonic speed and that is stored in the storage device. A distance from an ultrasonic wave sensor to a bottom surface of the piston is calculated based on the sonic speed and a measurement time length detected by the ultrasonic wave sensor.

Position detecting device for hydraulic cylinder, and detecting method thereof

An ultrasonic sensor is located in the bottom of a lift cylinder of a forklift and emits ultrasonic waves toward a piston in the cylinder. A controller controls the ultrasonic sensor to consecutively emit ultrasonic waves that have different amplitudes at predetermined intervals. The ultrasonic waves are emitted in order of smallness of amplitude. The controller computes the distance between the ultrasonic sensor and the piston based on a period from when the ultrasonic sensor emits one of the ultrasonic waves to when the ultrasonic sensor receives the ultrasonic wave that is reflected by the piston. As a result, the range of the detectable distances is extended.

Device and method for detecting position of movable body by using ultrasonic waves

In a position detecting device which detects a piston rod based on the time elapsed from a point at which an ultrasonic wave is emitted from an ultrasonic wave sensor toward a lower end surface of the piston rod reciprocatingly moved linearly by supply and discharge of a working oil with respect to a hydraulic cylinder to a point at which the ultrasonic wave reflected by the lower end surface of the piston rod is received by the ultrasonic wave sensor, if the working oil's temperature is detected by a temperature sensor, then a microcomputer sets the strength of the ultrasonic wave emitted from the ultrasonic wave sensor in accordance with the temperature of the working oil so as to accurately detect the position of the piston.

Position detecting device and industrial vehicle having the position detecting device

An anti-vibration member is provided on an inner wall of a cylinder tube of a lift cylinder. The anti-vibration member is formed into a cylindrical form, and an outer circumferential surface thereof is formed along an inner circumferential surface of the cylinder tube. The anti-vibration member is formed by coating resin high in ultrasonic wave attenuating effect (such as polyphenylene sulfide (PPS) resin). It is possible to attenuate or absorb a vibration of a surface wave transmitted from an ultrasonic wave sensor and indirectly transmitted through the inner wall of the cylinder tube.

Position detecting device for hydraulic cylinder, and industrial vehicle equipped with the position detecting device

An ultrasonic sensor detects whether a piston is at the lowest position. The sensor is not affected by the environment or damaged by contact with other objects. The sensor is located in the bottom of a mast cylinder, transmits ultrasonic waves to the bottom of a piston and receives ultrasonic waves reflected by the piston. The sensor then outputs electric signals based on the received ultrasonic waves. The ultrasonic sensor is electrically connected to a transmitter-receiver, which, in turn, is electrically connected to a controller. The transmitter-receiver includes an ultrasonic wave generator and sends ultrasonic wave transmitting signal having a predetermined frequency to the ultrasonic sensor based on control signals from the controller. The controller measures time from when it outputs the ultrasonic wave transmitting signal to when the sensor receives a reflected wave. The controller then compares the measured time with a threshold value thereby judging whether the piston is at the lowest position.

Lift cylinder and mast assembly of forklift

A position detector includes a fluid cylinder having a piston. An ultrasonic transceiver is provided at one end of the piston outside of the moving range of the piston. In response to electrical signals, the ultrasonic transceiver transmits ultrasonic waves to a reflection surface of the piston. The transceiver receives the ultrasonic waves reflected by the piston and then generates electrical signals representing the reflected waves. A sensor detects that the piston is at a predetermined position, at which the distance to the transceiver is known. A CPU supplies electrical signals to the ultrasonic transceiver to produce ultrasonic waves and receives electrical signals representing the reflected waves from the ultrasonic transceiver. The CPU then computes a piston position value, which is a function of the travel time from when an ultrasonic wave is transmitted to when the reflected wave is received and the speed of the waves. The CPU determines the speed of the waves when the piston is detected to be at the reference position. The CPU then computes the current position of the piston based on the speed of the waves and on a current reading of the travel time.

Position detector for fluid cylinder

A loading/unloading control apparatus for a industrial vehicle control the discharge capacity of a variable displacement type hydraulic pump in accordance with the detected result of the amount of load applied to a loading/unloading hydraulic actuator or with a manual setting by an operator, thereby to obtain the most suitable working speed of the actuator for loading/unloading operations.

Loading/unloading control apparatus for industrial vehicles

A controller in which a starting state is detected for the controller to control a displacement varying mechanism of the pump by the detected result of the starting state to minimize the discharge capacity of the pump, thereby minimizing the driving load of the pump. In this manner, the starting properties of the engine are improved to reduce consumption of energy at the starting time.

Driving load controller for variable displacement type hydraulic pump

A controller for a hydraulic fluid flow control apparatus determines a quantity necessary for loading/unloading operations according to a signal from a lever operating degree detector, and controls a variable displacement type hydraulic pump to obtain the quantity. Accordingly, unnecessary hydraulic fluid flow in the hydraulic apparatus is reduced. The controller determines when a vehicle is stopped according to a signal from a clutch ON-OFF detector or a neutral sensor, and can raise the rpm of an engine. Therefore, when the loading/unloading operations are being executed while the vehicle is stopped, there is no need to operate the accelerator pedal.

Growing community of inventors

Aichi-ken, Japan

Katsumi Nagai