Self-propelled construction machine and method for working ground pavements

Patent metadata

Field	Value
Publication number	US-2021016661-A1
Application number	US-202016897512-A
Country	US
Kind code	A1
Filing date	Jun 10, 2020
Priority date	Jul 18, 2019
Publication date	Jan 21, 2021
Grant date	—

Abstract

A self-propelled construction machine comprises a machine frame, at least three travelling devices, at least one hydraulic drive system for driving at least two travelling devices, wherein the hydraulic drive system comprises at least one controllable hydraulic motor with variable displacement volume and at least one hydraulic pump, at least one working device (e.g. a milling drum), for working the ground pavement. A detection device detects fluctuations in the longitudinal speed of the construction machine during movement thereof, wherein a control unit alters the displacement volume of the at least one controllable hydraulic motor as a function of the detected fluctuations so that the natural frequency of the hydraulic drive system is altered, wherein the control unit adjusts the discharge volume of the pump as a function of the amount of adjustment of the displacement volume in such a fashion that the specified drive speed remains constant.

First claim

1 - 15 . (canceled)

16 . A self-propelled construction machine comprising:
a machine frame; at least three travelling devices; at least one hydraulic drive system for driving at least two of the at least three travelling devices, wherein the hydraulic drive system comprises at least one controllable hydraulic motor with variable displacement volume and at least one hydraulic pump; at least one milling drum for working the ground pavement; a detection device configured to detect fluctuations in a longitudinal speed of the construction machine during movement thereof; and a control unit configured to
adjust the displacement volume of the at least one controllable hydraulic motor as a function of the detected fluctuations, wherein a natural frequency of the hydraulic drive system of the construction machine is adjusted thereby, and
adjust a discharge volume of the pump as a function of an amount of adjustment of the displacement volume such that a specified drive speed remains constant.

17 . The self-propelled construction machine of claim 16 , wherein the control unit adjusts the natural frequency of the construction machine by reducing the displacement volume of the at least one controllable hydraulic motor.

18 . The self-propelled construction machine of claim 16 , wherein the detection device is configured to detect vibration corresponding to fluctuations in the longitudinal speed of the construction machine.

19 . The self-propelled construction machine of claim 18 , wherein said detected vibration exhibits an essentially fixed frequency.

20 . The self-propelled construction machine of claim 18 , wherein the control unit is configured to control the hydraulic drive system such that the displacement volume of the at least one controllable hydraulic motor is adjusted only when the detected vibration exceeds a predefined amplitude.

21 . The self-propelled construction machine of claim 16 , wherein the control unit is configured to control the hydraulic drive system such that the displacement volume of the at least one hydraulic motor and the discharge volume of the hydraulic pump are adjusted simultaneously.

22 . The self-propelled construction machine of claim 16 , wherein the control unit is configured to
verify whether the detected longitudinal speed deviates from the specified drive speed, and in the case of a deviation, to adjust the discharge volume of the hydraulic pump until the detected longitudinal speed corresponds to the specified drive speed.

23 . The self-propelled construction machine of claim 16 , further comprising:
a data storage device having data stored therein which show a correlation between the pressure in the hydraulic drive system and speed losses; and at least one measuring device configured to measure the pressure in the hydraulic drive system, wherein the control unit is configured to adjust the discharge volume of the hydraulic pump as a function of the measured pressure such that the speed losses are compensated for and the longitudinal speed corresponds to the specified drive speed.

24 . The self-propelled construction machine of claim 16 , wherein the detection device is configured to detect fluctuations in the longitudinal speed via one or more of:
on the travelling devices; on the machine frame; as a fluctuation in the volumetric flow rate; and as a fluctuation in the pressure of the hydraulic drive system.

25 . The self-propelled construction machine of claim 24 , wherein the detection device comprises one or more of:
a pick-up sensor; an accelerometer for measuring the speed changes; and a measuring device for measuring the fluctuations in pressure or the volumetric flow rate in the hydraulic drive system.

26 . A method for working ground pavements using a construction machine self-propelled by means of travelling devices, in which the travelling devices are driven by a hydraulic drive system, wherein the hydraulic drive system comprises at least one controllable hydraulic motor with variable displacement volume and at least one hydraulic pump, and wherein a working device works the ground pavement, the method comprising:
detecting fluctuations in the longitudinal speed of the construction machine during movement thereof; adjusting the displacement volume of the at least one controllable hydraulic motor as a function of the detected fluctuation, wherein a natural frequency of the hydraulic drive system of the construction machine is adjusted thereby; and adjusting a discharge volume of the pump as a function of the amount of adjustment of the displacement volume, such that a specified drive speed remains constant.

27 . The method of claim 26 , wherein the fluctuations in the longitudinal speed of the construction machine are detected as vibrations.

28 . The method of claim 27 , wherein said vibrations exhibit an essentially fixed frequency.

29 . The method of claim 27 , further comprising:
controlling the hydraulic drive system such that the displacement volume of the at least one controllable hydraulic motor is adjusted only when the detected vibration exceeds a predefined amplitude.

30 . The method of claim 26 , wherein the displacement volume of the at least one controllable hydraulic motor is reduced to adjust the natural frequency of the construction machine.

31 . The method of claim 26 , wherein the displacement volume of the at least one hydraulic motor and the discharge volume of the hydraulic pump are adjusted simultaneously.

32 . The method of claim 26 , further comprising:
after adjusting the displacement volume and the discharge volume, verifying whether the detected longitudinal speed deviates from the specified drive speed, and in the case of a deviation, adjusting the discharge volume of the hydraulic pump until the detected longitudinal speed corresponds to the specified drive speed.

33 . The method of claim 26 , further comprising:
after adjusting the displacement volume and the discharge volume, verifying the pressure in the hydraulic drive system and, as a function of the pressure and as a function of data stored in a data storage device which show the correlation between the pressure in the hydraulic drive system and speed losses, adjusting the discharge volume to compensate for the speed losses.

34 . The method of claim 26 , wherein the fluctuations in the longitudinal speed are detected via one or more of:
on the travelling devices; on the machine frame; as a fluctuation in the volumetric flow rate; and as a fluctuation in the pressure of the hydraulic drive system.

Assignees

• Wirtgen Gmbh

Inventors

• Wagner Stefan
• Bach Markus
• Mahlberg Axel
• Schäfer Markus
• Fitz Eduard

Classifications

• E21C29/22

  by wheels, endless tracks or the like {(propulsion using fixed racks along which the machine is running E21C29/02)} · CPC title

• E21C25/10

  Rods; Drums · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• E02F3/84

  Drives or control devices therefor {, e.g. hydraulic drive systems} · CPC title

• E01C23/127

  rotary, e.g. rotary hammers · CPC title