The invention relates to a regulating device for a hydrostatic piston engine.
Hydrostatic piston engines which can be adjusted in their absorption or discharge volume are usually used for operating hydrostatic drives. In this case an adjusting device, triggered by a regulating device, acts on an adjusting mechanism of the hydrostatic piston engine.
From DE 195 40 654 C1 a regulating valve is known for this purpose, in which a valve piston is arranged as longitudinally displaceable in a valve housing. The valve piston can be charged with a control pressure on each of its end faces orientated in opposite directions. By an axial movement of the valve piston in one direction an input pressure connection is connected to a first output by displacing the sealing area. Simultaneously a second output is connected to a tank connection. On a movement in the opposite direction the second output connection is connected to the input connection and simultaneously the first output connection is connected to the tank connection. The resulting adjusting movement of the adjusting piston is fed back to the valve piston via a feedback element, in order to achieve an adjustment of the adjusting piston proportional to the force acting on the end face of the valve piston. The adjusting movement is transmitted by the feedback element and steers out one of two legs. The two legs are connected to one another via a spring, the leg not steered out in each case being supported on a catching pin of the valve piston. The known adjusting device has the disadvantage that the mechanical feedback involves a considerable outlay.
The object of the invention is to create a regulating device for a hydrostatic piston engine, which enables simple detection of the position of the adjusting piston.
The regulating device according to the invention for a hydrostatic piston engine comprises an electronic control unit. The electronic control unit is provided for generating adjusting signals. So that the electronic control unit can take into account the respective current position of the pivoting angle of the hydrostatic piston engine, a feedback element is provided in the regulating device. The feedback element scans the adjusting position of the hydrostatic piston engine. The adjusting position scanned by the feedback element is detected without contact by a sensor element integrated in the electronic control unit.
Because of the provision of a sensor element which detects a scanned adjusting position without contact, there is no need for the mechanical feedback. The sensor element can therefore be provided on a printed circuit board of the electronic control unit and cabling is not required. Simultaneously, by the provision of a sensor element for contactless detection, mounting safety and operating safety are increased. By contrast with mechanical feedback of the adjusting position to a regulating valve, the position is detected without contact and immediately taken into account in the adjusting signal generated. Finally, the contactless detection of the scanned adjusting position allows sealing of the electronic components from the areas of the hydrostatic piston engine which are oil-bearing.
Advantageous further developments of the regulating device according to the invention are listed in the subordinate claims.
It is particularly advantageous to construct the regulating device with a first and a second housing part. The electronic control unit may in this case be arranged in a first housing part and the feedback element in a second housing part. The division provides a simple option for separating the electronic components and the mechanical/hydraulic components from one another. The two housing parts can in particular be sealed against one another in a simple manner.
Particularly simple transmission and detection of the adjusting position of an adjusting device of the hydrostatic piston engine can be achieved, if a magnetic element is provided on the feedback element and the electronic control unit has a magnetically sensitive sensor element. If the two housing parts, in which the electronic control unit or the mechanical/hydraulic components are preferably arranged, consists of a material which, for example, prevents optical detection of the adjusting position, contactless detection of the adjusting position is easily possible by using a magnet in combination with a magnet-sensitive sensor element.
A particularly favourable arrangement emerges if the feedback element has a shaft which is held rotatably in the regulating device. By means of such a rotatably held shaft a measuring variable for the scanned adjusting position of the hydrostatic piston engine can be determined in a small construction space on the basis of the angle of the shaft of the feedback element.
To translate, in most cases, a linear adjusting movement of an adjusting device of the hydrostatic piston engine into an item of angle information, a feedback lever is preferably non-rotatably connected to the shaft of the feedback element. The feedback lever can be guided out of a housing of the regulating device in such a way that the entire regulating device is placed as a modular component on to an existing hydrostatic piston engine of conventional design. The feedback elements of conventionally mechanically fed back engines can be partially reused. For this purpose the feedback lever engages in a corresponding recess of the adjusting device of the hydrostatic piston engine. The linear movement is converted into a rotating movement of the shaft by the feedback lever which is non-rotatably connected to the shaft. In this case the magnetic element is particularly preferably arranged on the shaft. The magnetic element is preferably arranged on the end face of the shaft, so when the shaft rotates a constant distance between the magnetic element and the sensor element on the printed circuit board of the electronic control unit is guaranteed.
The angle of the magnetic element and therefore the adjusting position of the hydrostatic piston engine can be detected in a particularly simple manner by a Hall sensor as sensor element or by a magneto-resistive resistor.
It is further advantageous to detect the temperature of the hydrostatic piston engine directly in the electronic control unit. For this, a temperature sensor is arranged in the electronic control unit. The close arrangement of the electronic control unit on the hydrostatic piston engine provides a clear connection between the operating temperature of the hydrostatic piston engine and the temperature measured in the electronic control unit.
In order to further improve detection of the temperature of the hydrostatic piston engine, the first housing part and the second housing part are preferably constructed of a metal material, so the temperature sensor of the electronic control unit measures a virtually identical temperature to the operating temperature of the hydrostatic piston engine.
A preferred embodiment example of the regulating device according to the invention is illustrated in the drawings and is explained in greater detail in the following description.
Before examining the configuration of the regulating device according to the invention, firstly, using the schematic wiring diagram of
An adjusting device 3 acts on the adjusting mechanism of the hydrostatic piston engine 1. The adjusting device 3 has a cylinder 4, in which an adjusting piston 5 is arranged as longitudinally displaceable. The adjusting piston 5 has two adjusting pressure faces, facing in opposite directions, by which the cylinder 4 is divided into a first adjusting pressure chamber 6 and a second adjusting pressure chamber 7. Provided for transmitting the adjusting movement of the adjusting piston 5 is a piston rod 8, which is mechanically coupled to the adjusting mechanism of the hydrostatic piston engine 1.
The adjusting movement of the adjusting piston 5 is generated by setting appropriate adjusting pressures in the first adjusting pressure chamber 6 and the second adjusting pressure chamber 7. To set the adjusting pressures, an adjusting pressure regulating valve 9 is provided, which charges the first adjusting pressure chamber 6 or the second adjusting pressure chamber 7 with an adjustable pressure via a first adjusting pressure line 10 and a second adjusting pressure line 11. The adjusting pressure regulating valve 9 is a 4/3 directional control valve, by which the first adjusting pressure line 10 or the second adjusting pressure line 11 can be connected alternately to a pressure feed line 12 or a pressure relief line 13. Via the pressure relief line 13 pressure means, taken from one of the adjusting pressure chambers 6, 7 is relieved into the tank volume 14. The adjusting pressure regulating valve 9 is continuously adjustable between its two end positions. The position of the adjusting pressure regulating valve 9 is fixed by a first electromagnet 15 and a second electromagnet 16. The adjusting pressure regulating valve 9 is preferably a proportional valve. Various embodiments of such a proportional valve in the form of proportional directional control valves or pressure-reducing valves are explained later with reference to
The adjusting signals for the electromagnets 15, 16 are generated by an electronic control unit 17 and conveyed to the electromagnets 15, 16 via adjusting signal lines 18 or 19.
In order to be able to determine the adjusting signals for the first electromagnet 15 or the second electromagnet 16, various input variables are fed to the electronic control unit 17. As well as the central input variable, which is fed, for example, by a driving lever default of an operator via a line 20, these are, e.g. variables of the hydraulic system itself. In addition to detection of the pressures prevailing in the operating lines 25, 26, not separately illustrated in
The actual adjusting position of the adjusting piston 5 corresponds to the set absorption or discharge volume of the hydrostatic piston engine 1. In the schematic illustration of
The feedback lever 36 has an eye 38, which is penetrated by the shaft 61. The geometry of the eye 38 and the geometry of the shaft 61 at this point are chosen in such a way that a rotating movement of the feedback lever 36 means a rotation of the shaft 61 in the recess 35. On its feedback-lever-side end the shaft 61 has a bolt-shaped extension which engages in a pocket hole 39 of the second housing part 34 and thus enables improved bearing of the shaft 61. Between the feedback lever 36 and a wall 34′ of the second housing 34 is arranged a spacer disc 40 to keep the friction between the feedback lever 36 and the wall 34′ as low as possible.
On the end of the shaft 61 facing away from the connection to the feedback lever 36 is constructed a magnet receptacle 41. In the embodiment example illustrated the magnet receptacle 41 is implemented on the end face of the shaft 61 by a countersunk groove. A magnet, not illustrated in the drawing, is inserted into this groove. The magnet is preferably designed as a permanent magnet.
In the neutral position illustrated in
In the first housing part 33 is constructed an accommodating space 64 for accommodating the electronic control unit 17. This accommodating space 64 is closed by a cover 60, by which simultaneously the printed circuit board 43 is held down and is thus fixed on the first spacer 45 and the second spacer 46. The part of the recess 35 which is constructed in the first housing part 33 is inserted into the first housing part 33 from outside and has no connection to the accommodating space 64. Scanning the relative position of the magnet, inserted into the magnet receptacle 41, by the sensor element 42 takes place through the housing wall without contact. For this purpose the flux lines of the permanent magnet penetrate through the wall of the first housing part 33 in the area between the magnet receptacle 41 and the sensor element 42. For detecting the relative position of the permanent magnet the sensor element 42 is preferably designed as a Hall sensor, which, e.g. reacts to changes of angle of a parallel magnetic flux density. Alternatively the sensor element 42 may also be constructed as a magneto-resistive element.
In addition to recess 35, in the second housing part 34 a valve piston recess 51 is provided, in which a valve piston 52 is arranged as longitudinally displaceable. In the sectionalised area illustrated the valve piston recess 51 is connected to a duct 53, which ends at a contact face 54 of the second housing part 34. The duct 53 stands perpendicular on the recess 35 and enables the feedback lever 36 to be guided outwards out of the second housing part 34. The contact face 54 constructed on the outside serves to fasten the regulating device 30 to the housing part 32 of the adjusting device of the hydrostatic piston engine 27.
Likewise connected to the duct 53 is a bore 56, which in turn intersects with a bore 57. Bores 56, 57 act jointly with the duct 53 to feedback pressure medium in the direction of a tank volume, not illustrated.
In order to prevent leaked medium escaping from the second housing part 34, the bore 56 is closed with a plug 65. For fastening, threaded pins 58 protrude out from the contact face 54, via which the regulating device 30 can be screwed to the housing part 32. Additionally to be seen is an alignment pin 59, via which the exact position of the regulating device 30 is fixed in respect of the housing part 32, in order, for example, to enable secure sealing of adjusting pressure ducts guided through the contact face 54.
The use of sensors arranged on the printed circuit board for detecting temperature and position allows improved consideration of operating parameters, without additional external sensors. In particular, a neutral position can be varied by software and temperature-dependent swivelling back behaviour implemented, wherein ventilator control can also be integrated.
A greatly simplified illustration of a regulating device 30 according to the invention in perspective view is illustrated again in
The initial position of the two 3/2 directional control valves 92, 93 illustrated in
Alternatively to the proportional directional control valve unit 91, according to a further embodiment the further proportional directional control valve unit 95 illustrated in
The second electromagnet 16 is appropriately actuated to effect a displacement of the adjusting piston 5 in the opposite direction. A balance of forces arises between the hydraulic force which acts on the pressure-reducing valve 98 in the opposite direction to the force of electromagnet 16 and the adjusting force of electro-magnet 16.
The invention is not confined to the embodiment example illustrated. In fact, any number of combinations of the features illustrated and explained in the drawings is possible.
Number | Date | Country | Kind |
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10 2005 037 620 | Aug 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2006/007845 | 8/8/2006 | WO | 00 | 3/7/2008 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2007/017251 | 2/15/2007 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
6394206 | Fury | May 2002 | B1 |
6802243 | Matsuda et al. | Oct 2004 | B2 |
7124677 | Kadlicko | Oct 2006 | B2 |
7380490 | Kadlicko | Jun 2008 | B2 |
Number | Date | Country |
---|---|---|
195 40 654 | Dec 1996 | DE |
100 06 405 | Sep 2001 | DE |
0 955 465 | Nov 1999 | EP |
Number | Date | Country | |
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20100224058 A1 | Sep 2010 | US |