DE2401950A1 - POWER SUPPORT STEERING DEVICE FOR VEHICLES - Google Patents

Description

"Servo-assisted steering device for vehicles"

Priority: January 16, 1973; Great Britain; Registration no .: 2335/73.

The invention relates to a working with power assistance Steering device for vehicles «It is particularly suitable for use in forklifts and other in-industry used cargo transport vehicles. Furthermore, the invention also relates to vehicles that are equipped with such a steering device are provided.

The invention is based, in particular, on the object that, through various influencing factors, in particular load, but also speed, to compensate for the differences caused in the steering effort as much as possible.

409830/0833

A servo-assisted working according to the invention Steering device for vehicles has devices for detecting the wheel load of the steered vehicle wheels or one of them traceable load and devices that increase the servo effect with increasing wheel load.

The steering system according to the invention preferably also includes devices that reduce the servo effect with increasing Cause vehicle speed. This allows for a suitable increase in the servo assistance of the system achieve an increase in the wheel load of the steered wheels as well as a suitable decrease in the servo power assistance at a Increase in speed of the vehicle, which always means a relatively constant overall steering effort.

The invention can be used particularly expediently in forklift load conveyors working with a load counterweight, where the steered rear wheels when picking up loads be relieved; here are facilities according to the invention the steering system provided, which the servo action. with increasing Reduce payload. Advantageously, in this case, those for detecting a due to the wheel load of the steered wheels are returned The devices provided for the load are directly equivalent to those of the Detect the vehicle picked up load and the steering force gain accordingly lower when the vehicle is loaded.

409630/0833

" ³ - 2A01950

The invention is illustrated below with reference to a schematic. drawing explained in more detail using an exemplary embodiment, namely on a servo-assisted steering system for the Use with a conventional forklift truck.

In the arrangement according to the figure, a propulsion motor 12 of the forklift is controlled by a control unit which controls the motor speed 13 powered by a battery 11.

The steered wheels of the forklift are located above a control valve 15 with a L n '<": raf t servo unit 14 in connection, the is fed by a hydraulic pump 16, which in turn drives a pump motor 17.

The pump motor 17 has an electrical connection to a thyristor pulse control unit which monitors the running speed of the pump 16 18 on.

A load sensor 19 is attached to the forklift truck so that it one proportional to the load on the forks and thus the reverse of the wheel load on the controlled rear wheels of the forklift proportional signal generated; the load sensor is still at a standstill 19 in an operative connection to the control device 18 for the pump running speed or rotational speed in such a way that when the load increases, the running speed of the pump 16 is reduced.

-A-

409830/0833

The control device 18 also stands for the running speed or the speed of the pump also in operative connection with the control unit 13 for the speed of the propulsion motor, and a second signal proportional to the speed of the propulsion motor is provided by this speed control unit 13 tapped and fed to the control device 18 for the pump running speed, which is designed so that at an increase in speed of the propulsion motor 12 causes a decrease in the running speed of the pump 16.

It goes without saying that the system is within the scope of the invention can be modified in many ways; for example, the Sigric ?! can be picked up by a tachometer coupled to this motor.

If the pump 16 continues to be used for charging others Systems is required, the oil supply to the power steering servo unit 14 can be controlled by a flow splitter, which is responsive to a preferred application of the steering force support system is aligned.

Furthermore, the pump motor 17 can drive a tachometer, the task of which is to reduce fluctuations in the Oil supply to give a feedback signal to the control device for the pump speed with changing loads.

Expectations U Ü ü ei ο ü / U 8 3 3

Claims (5)

Expectations 1. ι Steering device working with servo assistance _ £ j / ng for vehicles, marked, t by a device (19) for detecting the wheel load of the steered vehicle wheels or a load that can be traced back to them and a device (18) that increases the servo effect causes increasing wheel load. 2. Steering device according to claim 1, characterized by a device which decreases the servo effect with increasing Causes vehicle speed. 3. Steering device working with power assistance for use with a counterbalanced forklift or other industrial load handling or vehicles which manipulate loads and in which a payload causes a wheel load reduction on the steered wheels by a device which reduces the servo gain as the payload increases. 4. Steering device according to one of claims 1 to 3 for use in a vehicle with an electric drive unit and a hydraulic servo unit with an electric pump drive, in particular an electric vehicle, characterized by U 0 9 ü ό U / Ü 8 3 3 net that it has a load sensor (19) which generates a signal proportional to the wheel load of the steered wheels and with a Control device (18) for the drive motor of the servo pump is connected in such a way that the running speed or rotational speed of the pump motor is varied depending on the wheel load of the steered wheels. 5. Steering device according to claim 4, characterized by " a device for generating a signal proportional to the vehicle speed, which is connected to the control device for the Running speed of the pump motor is in Kirk connection, that as the vehicle speed increases, the speed of the pump motor is reduced. ORIGINAL INSPECTED