US 4,896,582 A · Method for reducing the piston speed, especially in the piston and cylinder assemblies of an excavating machine, and device for carrying out the method

Abstract

The invention relates to a method and a device for reducing the piston speed in a piston and cylinder assembly (1), as the piston approaches the end position. The piston end position is sensed, and a signal is generated for starting the end position dampening. Dampening is effected in two steps. In the first step (14), a time delay is provided and in the next step (15), the actual braking (retardation) of the piston is effected. The invention also comprises an electronic braking device comprising a dampening activation unit (13) which is connected to transducers (6), a braking delay unit (14) connected to the unit (13) and also to the control lever (5) at issue and a reference signal source, as well as a braking unit (15) connected to the delay unit (14) and adapted, upon activation, to provide a signal (U) to a setting system (3) for controlling the supply of pressure fluid to the piston and cylinder assembly (1).

Claims11

Dependent claims

Method for reducing speed of a piston in a piston and cylinder assembly as the piston approaches end positions of the cylinder, said method comprising the steps of:

generating a position signal when the piston passes a predetermined position adjacent ends of the cylinder;
supplying the position signal to a signal processing system;
supplying the position signal, a reference signal and a control lever signal to a delay unit;
comparing the control lever signal to the reference signal with the delay unit;
generating a comparison signal after a delay time period based on the comparing;
applying the comparison signal and the control lever signal to a braking unit;
processing the comparison signal and control lever signal by the braking unit to generate an output signal;
applying the output signal and a signal indicating direction of piston travel to a setting system;
and
controlling supply of pressure medium to the piston and cylinder by the setting system to thereby reduce the speed of the piston.

7 more elements

Device for reducing speed of a piston in a piston and cylinder assembly as the piston approaches end positions of the cylinder, the device comprising:

a signal transducer adapted to sense when the piston passes a predetermined position adjacent ends of the cylinder;
control means for generating a positive or negative control signal for respectively extending and retracting the piston and cylinder assembly;
a pressure medium system;
a setting system operatively connected to the pressure medium system for controlling the pressure medium system and supply of pressure medium to the piston and cylinder assembly;
a delay unit for receiving a position signal generated when the piston passes the predetermined position and receiving a reference signal and a control lever signal, said delay unit being activated by the position signal to compare the control lever signal with the reference signal and to generate a comparison signal after a delay time period;
and
a braking unit for receiving and processing the comparison signal and the control lever signal to generate an output signal, said output signal together with a direction signal indicating a direction of piston travel being applied to the setting system to control the supply of pressure medium to the piston and cylinder assembly.

4 more elements

Dependencies are inferred from the claim text.

Method for reducing the piston speed, especially in the piston and cylinder assemblies of an excavating machine, and device for carrying out the method

Life of this patent

Method for reducing the piston speed, especially in the piston and cylinder assemblies of an excavating machine, and device for carrying out the method

Life of this patent

Abstract

Claims11