The invention relates to a control device for controlling a hydraulic consumer, such as a working cylinder. In particular, the invention relates to the control of working cylinders, which can be used in vehicles being subject to changing load conditions and having a hydropneumatic suspension system as a level control system.
Control devices of this type are state of the art, for example, DE 10 2004 040 636 A1. The known solution provides two line main branches for supplying the respective working cylinders in the form of a suspension cylinder. The line main branches are connected to the annular chamber or the piston chamber of the respective working cylinders in the form of a suspension cylinder. Three switching valves, one of which is electromagnetically actuated, and a pressure control valve are installed in the main branches extending between a pump port and a tank port for the controlled pressure supply of the respective annular chamber and piston chamber. Because four valves are used, the known solution has the disadvantage of high manufacturing cost and requires considerable effort to operate several valves including the control of two valve solenoids.
Based on this state of the art, the invention addresses the problem of providing a control device of the type mentioned above, which is characterized by a low-cost construction and can be operated applying little control effort, in particular when used to control a working cylinder used as a level control system.
According to the invention, this problem is basically solved by a control device for controlling a hydraulic consumer, such as a working cylinder, comprising of at least one control valve having a control spool. The control spool is guided in a valve housing in a longitudinally movable manner, can be actuated by an electric motor and can be controlled by control electronics. The control electronics receive input signals from a sensor device that detects at least one operating state of the consumer. Because the functions of three switching valves and one pressure control valve are taken over by a spool valve that can be actuated by an electric motor, the cost of cost-intensive components is reduced. The control effort is also simplified, because only the electric motor of the spool valve has to be controlled and not three independent valves, including two actuating magnets. This control device also provides the option of implementing the control device as a unit having integrated control electronics. The wiring effort compared to the known solution is also reduced in this way.
In an advantageous embodiment of the control device, there is at least one pressure supply port, one return port on the input side of the valve housing, at least two utility ports for the hydraulic consumer and two control ports for the connection of hydraulically unlockable valves, in particular check valves, on the output side.
In addition to the existing ports a load sensing port can be provided on the inlet side of the valve housing for controlling a regulating pump, which is used to generate pressure for the pressure supply port.
In particularly advantageous embodiments, the electric motor actuating the spool of the control valve is a brushless DC motor, which actuates the spool by a rack and pinion drive. Advantageously, the electromotive actuation of the control spool can be formed as shown in DE 10 2015 015 685 A1 for the control spool of a LS directional valve. In accordance with this solution, in an advantageous embodiment of the invention, the electric motor is arranged on the valve housing such that its drive axis perpendicularly intersects the travel axis of the control spool and a pinion, located at the end of the motor shaft. The pinion is in engagement with a rack connected to the control spool within a housing chamber. For the control of the stepper motor, as shown in the document mentioned above, an electronics housing is attached to the motor housing to accommodate an electronics board. The electronics board may have a digital controller that detects the rotational position of the motor, for example, by sensorless position measurement. The control may be performed via a CAN bus.
The sensor device, provided for the detection of operating conditions of the consumer, may have at least one sensor, which is used for the detection of displacement and/or of speed and/or of pressure.
A working cylinder, provided as a hydraulic consumer, may have a piston-rod unit, which can be moved in a cylinder housing and which divides the cylinder housing into an annular chamber and a piston chamber. The annular chamber can be connected to one of the utility ports, the piston chamber can be connected to the other utility port, in fluid-conveying manners.
Advantageously, the sensor device has two pressure sensors, which measure the pressure in the annular chamber and the pressure in the piston chamber.
In accordance with the device provided for in the aforementioned document DE 10 2015 015 685 A1, the arrangement in an embodiment may be such that in a middle position, supported by an energy storage device, such as a compression spring, all ports on the output side of the valve housing are shut off from the pressure supply port.
In that case, the arrangement can further be such that, on both sides of the middle position, the control spool performs two further control functions, i.e. a switching position for retracting the piston-rod unit, a switching position for charging the annular chamber, a switching position for charging the piston chamber and a switching position for extending the piston-rod unit.
If the hydraulic consumer is formed as a suspension cylinder of a level control system in vehicles, the annular chamber and the piston chamber can be connected to one hydraulic accumulator each.
Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses a preferred embodiment of the present invention.
Referring to the drawings that form a part of this disclosure:
With reference to the attached drawings, the control device according to the invention is explained based on the example of the control of a hydraulic consumer in the form of a suspension cylinder 2, which is part of the level control system of a vehicle. The piston rod 4 of the suspension cylinder 2 is loaded by varying axle loads during driving. The control device according to the invention is equally suitable for the control of hydraulic consumers for other purposes. To function as a suspension element, the annular chamber 6 of the cylinder 2 is connected to a hydraulic accumulator 8 and the piston chamber 10 of the cylinder 2 is connected to a hydraulic accumulator 12. A first line main branch 14 is used to supply the annular chamber 6, and a second line main branch 16 is used to supply the piston chamber 10 with pressure. Each of the line main branches 14, 16 establishes a connection to the output side of a control valve 18.
The control valve 18 is a proportional spool valve, the control spool 20 of which can be longitudinally moved in a valve housing 22 by an electric motor 24. On the whole, the construction of the spool valve and of its electromotive actuation, as shown in
As shown in
As can be seen most clearly in
During operation for setting the control valve 18 to the switching positions, the controller MC receives from a pressure sensor 58 a pressure signal MR representing the pressure in the annular chamber 6, and from a pressure sensor 60 a pressure signal MK representing the pressure in the piston chamber 10. A displacement sensor 62 on the cylinder 2 provides a position signal IS. Depending on the input signals, the control spool 20 is on both sides of the center position adjustable to two further switching positions each, which are shown separately in
Finally,
While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.
Number | Date | Country | Kind |
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10 2018 004 769.6 | Jun 2018 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/064849 | 6/6/2019 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2019/238534 | 12/19/2019 | WO | A |
Number | Name | Date | Kind |
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5722460 | Olsen | Mar 1998 | A |
6247494 | Deininger | Jun 2001 | B1 |
6854270 | Zenker | Feb 2005 | B2 |
7591448 | Martin | Sep 2009 | B2 |
8020485 | Jessen | Sep 2011 | B2 |
9200647 | Jadhav | Dec 2015 | B2 |
20030205128 | Zenker et al. | Nov 2003 | A1 |
20090051130 | Huth | Feb 2009 | A1 |
20140352524 | Mullen | Dec 2014 | A1 |
20170328380 | Coolidge | Nov 2017 | A1 |
20200300275 | Biwersi | Sep 2020 | A1 |
Number | Date | Country |
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88 04 060 | Apr 1989 | DE |
38 16 572 | Nov 1989 | DE |
199 09 712 | Sep 2000 | DE |
10 2004 040 636 | Feb 2006 | DE |
10 2015 015 685 | Jun 2017 | DE |
2 466 154 | Jun 2012 | EP |
Entry |
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International Search Report (ISR) dated Aug. 16, 2019 in International (PCT) Application No. PCT/EP2019/064849. |
Number | Date | Country | |
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20210262491 A1 | Aug 2021 | US |