Patent Application
20230089947
The invention relates to a control device for an oscillating axle suspension, in particular a front axle suspension, consisting at least of one hydraulic accumulator device, a suspension device and a proportional valve having a valve piston, wherein to said proportional valve the two devices are connected via fluid ports.
From DE 10 2004 040 636 A1 an control device for a suspension device is known, in particular for vehicles subjected to changing load conditions, having an axle suspension with
The known solution can be used to set a different spring characteristic for the respective suspension cylinder by varying the pressure on the ring end, wherein it is possible to define the spring characteristic from the outset as part of a conceptual design between operating limits for the spring characteristics.
The known axle suspension is not designed to oscillate, so that no roll stabilization is provided for such oscillating movements. Although front-axle suspension systems based on independent wheel suspensions have been implemented in practice, enabling oscillating operation of the front axle and thus also providing roll stabilization in conjunction with blocking and releasing the axle suspension, the known solutions require a large number of individual valves, however, that have to interact with one another in a sensible manner impairing functional reliability. Furthermore, owing to the large number of individual valve components used, the implementation of the known solutions is complex and therefore cost-intensive.
Furthermore, DE 10 2015 015 685 A1 discloses a valve device consisting of at least one valve piston disposed in a valve housing so as to be longitudinally movable along a travel axis by means of an electric motor, which piston at least partially connects or disconnects fluid ports disposed in the valve housing, such as a pressure supply port and two utility ports for a hydraulic load such that the valve piston can be actuated in a precise position within the valve housing for sensible operation via a conventional electric motor using an assignable computer unit when controlled appropriately.
Based on this state of the art, the invention addresses the problem of further improving the known control device to the effect that an oscillating axle suspension, in particular front axle suspension, can be implemented using few components in a cost-effective manner, which axle suspension is also functionally reliable in use. An control device having the features of claim 1 solves such a problem in its entirety.
In accordance with the characterizing part of claim 1, the valve piston, actuatable by an electric motor, is longitudinally guided in a valve housing of the pilot valve and controls the fluid ports, such that in at least one functional position of the valve piston the axle oscillation is active while the suspension is blocked and in at least one further second functional position of the valve piston the suspension is active while the axle oscillation is blocked, basically all the actuating operations necessary for the oscillation and springing of the axle suspension, including the blocking thereof, can be performed using only one single proportional valve, which can be actuated by the electric motor. This is without parallel in the prior art.
Owing to the proportional transition from the first functional position of the valve piston, in which the axle oscillates while the suspension is blocked, to the second functional position, in which the axle suspension is active while the oscillation is blocked, a pressure compensation between the hydraulic accumulator device and the suspension device is achieved. As a result, the first functional position of the valve piston can be formed “spool-tight” for the purpose of pressure compensation, without the need to provide devices for reducing the flow cross-section, such as nozzles, in a bypass. In addition, the proportionality of the valve permits variable damping of the suspension. Furthermore, the transitions between the individual functional positions are designed “harmoniously”, so that undesirable, jerky movements of the associated working machine are prevented.
In a particularly preferred exemplary embodiment, provision is made in a further third functional position of the valve piston, for the axle oscillation and a pressure compensation occurring between the hydraulic accumulator device and the suspension device. As a result, damping of the suspension system can be achieved with simultaneous axle oscillation.
In a further preferred exemplary embodiment, provision is made for both the axle oscillation and the suspension occurring in a further fourth functional position of the valve piston.
In another preferred exemplary embodiment, provision is made in an optional, additional functional position, for proportional damping being provided for the suspension device while the axle oscillation is blocked.
In a further preferred exemplary embodiment, provision is made for the hydraulic accumulator device to be formed from two hydraulic accumulators, preferably of identical design, the fluid ends of which are each connected to a fluid port in the valve housing, and for the valve piston to control the respective fluid-conveying connection to two further fluid ports in the valve housing, to each of which a suspension cylinder, preferably its piston end, of the suspension device is connected.
In a further preferred exemplary embodiment, provision is made for the valve housing to have two additional fluid ports, which can be controlled by means of the valve piston and which can be blocked in at least one of the functional positions, one of which additional fluid ports is connected to the piston end of one suspension cylinder and the other to the piston end of the other suspension cylinder. The design of the proportional valve using multi-port technology renders it particularly suitable for large volume flows.
In a further preferred exemplary embodiment, provision is made for the electric motor to act on a pinion gear of the valve piston via a gear disposed in a gear chamber, which valve piston, penetrated by a longitudinal duct, establishes pressure compensation between the gear chamber and a tank port or a return port in the valve housing. The pressure compensation permits the valve piston to be brought into its functional positions in a pressure-compensated manner, which valve piston can be moved by means of the electric motor via the pinion drive with a particularly high resolution in relation to the fluid ports.
In a further preferred exemplary embodiment, provision is made for the electric motor to be controlled by a computer unit, which receives at least sensor information from at least two pressure sensors, each of which is installed in a fluid-conveying connection between the valve piston and the respective suspension cylinder and/or the valve piston and the respective hydraulic accumulator. The respective pressure sensor connected to the fluid connection between the valve piston and the respective suspension cylinder can be used to detect the cylinder pressure in this suspension cylinder, thereby indirectly determining the axle load. Such a pressure sensor and additionally an respective pressure sensor connected to the fluid connection between the valve piston and the respective hydraulic accumulator, which can be connected to this suspension cylinder by means of the proportional valve, can be used to determine the differential pressure in the blocked state of the suspension for the purpose of checking or monitoring pressure compensation. This improves functional safety. The individual sensor can be part of the respective hydraulic accumulator or the respective suspension cylinder, in particular disposed therein.
Preferably, provision is also made for the electric motor to move the valve piston in two counter-directional directions of travel in the valve housing. This allows for a compact valve design.
Because preferably the electric motor and its gear housing are accommodated in a drive housing and are disposed on one end face of the valve housing free of fluid ports, the control device is designed to be particularly space-saving and can be connected to other control devices in a side-by-side arrangement to form control blocks.
For the actuation of the valve piston by means of the electric motor, a control unit in the form of integrated electronics (On Board Electronics, OBE) can be provided on the valve, which, connected to a CAN bus, actuates the electric motor. Integrated electronics of this kind free up two power outputs on the controller and reduce the amount of assembly and wiring required. Furthermore, the power consumption for a traverse movement of the valve piston is low. In addition, the design of the actuating device of the valve spool allows for the valve spool to remain in its current functional position, for instance in a de-energized state of the actuating device, until it is brought into another position by means of the electric motor, which proves to be favorable in terms of energy and which additionally improves the reliability of the control device.
Below, the control device according to the invention is explained in more detail with reference to the drawing. In the figures, in a general representation, not to scale,
The proportional valve 14 has a valve housing 24, in which a valve piston 26 is guided in a longitudinally movable manner. The valve piston 26 can be operated by an electric motor 28 and controls the fluid ports 16, 18, 20, 22 in such a way that the axle oscillation is activated in a first functional position of the valve piston 26 while the suspension is blocked and the suspension is activated in a second functional position of the valve piston 26 while the axle oscillation is blocked.
Furthermore, the valve piston 26 controls the fluid ports 16, 18, 20, 22 in such a way that, in a third functional position of the valve piston 26, the axle oscillation is activated and a pressure between the hydraulic accumulator device 10 and the suspension device 12 is compensated. In addition, provision is made for a fourth functional position of the valve piston 26, in which both the axle oscillation and the suspension are activated. In addition, the valve piston 26 has a fifth functional position, in which the suspension device 12 is proportionally dampened while the axle oscillation is blocked.
The valve housing 24 has a main housing part 30, through which a passageway 32 extends, in which the valve piston 26 is guided for longitudinal travel along its longitudinal axis 34. At one end region 36 thereof, the passageway 32 of the main housing part 30 is widened in the inner diameter 42 in the direction away from the valve piston 26 to form a shoulder 38 and a tapered widening 40 subsequent to the shoulder 38. The tapered widening 40 is provided in the central region of the passageway widening 44 between the shoulder 38 and one end 46 of the passageway 32 of the main housing part 30. In the area of the passageway widening 44 of the main housing part 30, the valve piston 26 is spaced apart from the main housing part 30.
An insert 48 is inserted into the passageway widening 44 as part of the valve housing 24. The insert 48 has a widening of its outer diameter in the direction facing away from the valve piston 26 matching the conical inner circumferential widening 40 of the passageway 32 of the main housing part 30, and an end-sided annular projection 52 extending fully away from the end 60, facing away from the valve piston 26, of the insert 48 in the radial direction. The outer diameter 53 of the annular projection 52 of the insert 48 is larger than the largest inner diameter 42 of the passageway 32 of the main housing part 30. In a state, in which a threaded section 54 is used to secure the insert 48 to the main housing part 30, the annular projection 52 of the insert 48 is in contact with an outer wall 56 of the main housing part 30 and its end face 58 facing the valve piston 26, is in contact with the shoulder 38 of the passageway 32 of the main housing part 30. The threaded section 54 between the insert 48 and the main housing part 30 is provided, viewed in the axial direction, between the conical passageway widening 40 and the end 60, facing away from the valve piston 26, of the passageway 32 of the main housing part 30. An annular groove 62 is formed in the outer periphery 61 of the insert 48 between its end 58 facing the valve piston 26, and its central region, and a sealing ring 64 is provided in the groove 62 and is in sealing contact with the main housing part 30.
The insert 48 has a tank or return port T on its side 65 facing away from the valve piston 26, from which tank or return port T a central fluid duct 68 extends through the insert 48 in the axial direction toward the valve piston 26. At the end 58, facing the valve piston 26, of the insert 48, the inner diameter 73 of the insert 48 is widened in a stepped manner to accommodate another sealing ring 72. A first annular inner diameter reduction 74 of the insert 48 for guiding the valve piston 26, having an inner diameter slightly larger than the outer diameter 76 of the valve piston 26, adjoins the shoulder-shaped inner diameter widening of the fluid duct 68, in a direction towards the end projection 52 of the insert 48. Subsequently, with the interposition of an area having a larger constant inner diameter relative to the first diameter reduction 74, a second annular inner diameter reduction 80 of the insert 48 is provided as an end stop for the valve piston 26, which second annular inner diameter reduction 80 having a smaller inner diameter than the outer diameter 76 of the valve piston 26.
There is a first 82, a second 84 and a third 86 annular recess in the central region of the valve piston 26 spaced apart from one another in the axial direction, viewed from its end 87 facing the insert 48 in the direction of its end 89 facing away from the insert 48. Viewed in longitudinal section, each recess 82, 84, 86 is shaped like a trough or U-shaped. Thus, each recess 82, 84, 86 of the valve piston 26, as viewed in longitudinal section, has a base 88, from the ends of which an oblique side wall part 90 each, extending outwards in the axial direction and at the same time in the radial direction, and a radial side wall part 92, extending therefrom only in the radial direction, extend away. The transition of the respective radial side wall parts 92 of respective recesses 82, 84, 86 to the full or largest outer diameter 76 of the valve piston 26 forms a first 94 and a second 96 control edge of this recess 82, 84, 86, viewed from its end 87 facing the insert 48, in the direction of its end 89 facing away from the insert 48.
A first fluid port 16 and a fourth 22 fluid port for the hydraulic accumulator device 10 as well as a second fluid port 18 and a third 20 fluid port for the suspension device 12 are provided at the valve housing 24. The fluid ports 16, 22 for the hydraulic accumulator device 10 and the fluid ports 18, 20 for the suspension device 12 can be intersected by a sectional plane shown in
The hydraulic accumulator device 10 has two hydraulic accumulators 98, 100, which are of the same design. The fluid end of one hydraulic accumulator 98 is connected to the first fluid port 16 via a first fluid line 102, and the fluid end of the other hydraulic accumulator 100 is connected to the fourth fluid port 22 via a fourth fluid line 104. One orifice 106 each is provided in the first 102 and fourth 104 fluid line.
The suspension device 12 has two suspension cylinders 108, 110. The piston end of one suspension cylinder 108 is connected to the second fluid port 18 via a second fluid line 109, and the piston end of the other suspension cylinder 110 is connected to the third fluid port 20 via a third fluid line 111. One suspension cylinder 108 is used to suspend one wheel of the front axle and the other suspension cylinder 110 is used to suspend the other wheel of the front axle.
One fluid duct 112 each extends from every fluid port 16, 18, 20, 22, respectively, through the valve housing 24 towards the valve piston 26 and discharges into a first 114, second 116, third 118, and fourth 120 control chamber in the valve housing 24, viewed from the end 56 of the valve housing 24 with the insert 48 towards its end 123 facing away from the insert 48. Specifically, the first fluid port 16 is connected to the first control chamber 114 in a fluid-conveying manner, the second fluid port 18 is connected to the second control chamber 116 in a fluid-conveying manner, the third fluid port 20 is connected to the third control chamber 118 in a fluid-conveying manner, and the fourth fluid port 22 is connected to the fourth control chamber 120 in a fluid-conveying manner. Every control chamber 114, 116, 118, 120 is disposed, as part of the passageway 32 through the valve housing 24, coaxially with the longitudinal axis 34 of the valve piston 26 and has an inner diameter larger than the inner diameter 42 of the guide parts 124, 126, 128 of the passageway 32 for guiding the valve piston 26, which guide parts 124, 126, 128 are each provided in particular between two adjacent control chambers 114, 116, 118, 120. In that way, the valve piston 26 extends through each of the control chambers 114, 116, 118, 120.
To the valve housing 24 on the end 123 having no fluid ports and facing away from the insert 48 a drive housing 132 adjoins, in which the electric motor 28 is disposed in such a way that a fictitious extension of its drive axis perpendicularly intersects the longitudinal axis 34 of the valve piston 26. A gear chamber 134 is provided in the drive housing 132, in which gear chamber 134 a drive pinion 136 that can be driven by means of the electric motor 28, meshes with a rack 138 of the valve piston 26. The rack 138 is attached to the end region 146 facing away from the insert 48, of the valve piston 26 and extends axially away therefrom into the gear chamber 134. The drive pinion 136 and the rack 138 in conjunction form a pinion drive.
The drive shaft of the electric motor 28 is operatively connected to the drive pinion 136 via a planetary gear, which is provided in a gear housing (not shown in the figures) disposed in the drive housing 132, wherein the gear housing is arranged between the electric motor 28 and the drive pinion 136. Such planetary gears are known from the prior art. In this regard, reference is made to DE 10 2015 015 685 A1.
The electric motor 28 can be used to move the valve piston 26 in two directions of travel in the valve housing 24, which directions are opposite to each other.
Between the fourth control chamber 120 and the end 123 facing the drive housing 132, of the valve housing 24, the inner diameter 42 of the passageway 32 is widened to form an annular groove 142, in which another sealing ring 144 is provided. At its end region 146 facing the drive housing 132, the outer diameter 76 of the valve piston 26 is reduced in the direction of the drive housing 132 while forming a tapered diameter reduction 148. An extension 150 is formed on the end 89 facing the drive housing 132, of the valve piston 26, which extension 150 has a further passageway 152 extending perpendicular to the longitudinal axis 34 of the valve piston 26. The further passageway 152 is used to engage an operating part of an emergency operating device (not shown in the figures). Such emergency operating devices are known from the prior art. In this regard, reference is made to DE 10 2015 015 685 A1.
A central longitudinal channel 154 extends through the valve piston 26, starting from its end 87 facing the insert 48, in the direction of the drive housing 132, which longitudinal channel 154 merges into a transverse channel 156 in the end region 146 facing the drive housing 132 and reduced in outer diameter 76, of the valve piston 26, wherein the two ends of said transverse channel 156 open out of the valve piston 26 into the gear chamber 134 in this region 146. The gear chamber 134 is connected to the tank port or the return port T in a fluid-conveying manner via the duct routing 154, 156 in the valve piston 26 and via the fluid duct 68 in the insert 48, for the purpose of establishing pressure compensation.
A pressure sensor (not shown in the figures) each is connected to the fluid-conveying connections 112, 109, 111 between the valve piston 26 and the respective suspension cylinders 108, 110. The sensor information acquired by means of the pressure sensors is fed to a computing unit (not shown in the figures), which is provided in the drive housing 132 in the sense of integrated electronics and by means of which the electric motor 28 can be controlled. The drive housing 132 comprises a connector part 158 for powering the computing unit and the electric motor 28 and for transmitting control commands to the computing unit.
In the fourth functional position 4 of the proportional valve 14 shown in
In the first functional position 1 of the proportional valve 14, the valve piston 26 is moved to its one end position towards the insert 48, in which end position it is in contact with the second annular inner diameter reduction 80 of the insert 48. In this travel position, the guide part 124 of the passageway 32 between the first 114 control chamber and the second 116 control chamber is in guiding contact with the full outer diameter 76 of the valve piston 26 between its first 82 recess and second 84 recess. Likewise, in this travel position, the guide part 128 is in guiding contact between the third 118 and fourth 120 control chambers with the full outer diameter 76 of the valve piston 26 at its end region 146 facing the drive housing 132. As a result, the respective fluid-conveying connections between the hydraulic accumulator device 10 and the suspension device 12 and between the hydraulic accumulators 98, 100 are blocked, thereby blocking the suspension. In addition, the base 88 of the second recess 84 of the valve piston 26, viewed in the axial direction, is disposed in the area of the guide part 126 between the second chamber 116 and the third 118 control chamber, such that a fluid-conveying connection free from constrictions of the flow cross-section is established between the two suspension cylinders 108, 110 of the suspension device 12. This enables the axle to oscillate while the suspension is blocked.
In the third functional position 3 of the proportional valve 14, the full diameter 76 of the valve piston 26, viewed in the axial direction, is disposed between the first recess 82 and the second 84 recess slightly offset in the direction of the drive housing 132 relative to the guide part 124 between the first control chamber 114 and the second 116 control chamber, such that this guide part 124 is located in the area of the sloping side wall 90 of the first recess 82. As a result, this guide part 124 forms an orifice with the adjacent second control edge 96 of the first recess 82, wherein the orifice narrowing the flow cross-section to and from the one hydraulic accumulator 98. Likewise, viewed in the axial direction, the full diameter 76 of the valve piston 26 at the end region 146 facing the drive housing 132, of the valve piston 26 is slightly offset in the direction of the drive housing 132 from the guide part 128 between the third 118 and fourth 120 control chambers, which guide part 128 is located in the area of the sloping side wall 90 of the third recess 86. As a result, this guide part 128 forms a further orifice with the adjacent second control edge 96 of the third recess 86, wherein said orifice narrows the flow cross-section to and from the one hydraulic accumulator 100. This permits the pressure between the hydraulic accumulator device 10 and the suspension device 12 to be compensated. In addition, the guide part 126 is disposed between the second control chamber 116 and third control chamber 118, viewed in the axial direction, in the area of the base 88 of the second recess 84. This provides a fluid-conveying connection free from constrictions of the flow cross-section to and from every suspension cylinder 108, 110, permitting axle oscillation and pressure compensation between the hydraulic accumulator device 10 and the suspension device 12.
In the second functional position 2 of the proportional valve 14, viewed in the axial direction, the guide part 124 is disposed between the first 114 and the second 116 control chamber in the area of the base 88 of the first recess 82, the guide part 126 between the second 116 and the third 118 control chamber is disposed in guiding contact with the full outer diameter 76 of the valve piston 26 between the first 82 and the second recess 84, and the guide part 128 is disposed between the third 118 and the fourth 120 control chamber in the area of the base 88 of the third recess 86. As a result, a fluid-conveying connection free from constrictions of the flow cross-section is established between the one suspension cylinder 108 and the one hydraulic accumulator 98, and a further fluid-conveying connection free from constrictions of the flow cross-section is established between the other suspension cylinder 110 and the other hydraulic accumulator 100, wherein the fluid-conveying connection and the further fluid-conveying connection are separate from each other. This activates the suspension while the axle oscillation is blocked.
In the fifth additional functional position 5 of the proportional valve 14, the full diameter 76 of the valve piston 26, viewed in the axial direction, is disposed at its end area facing the insert 48 slightly offset in the direction of the insert 48 relative to the guide part 124 between the first control chamber 114 and the second 116 control chamber, such that this guide part 124 is located in the area of the sloping side wall 90 of the first recess 82. As a result, this guide part 126 forms an orifice with the adjacent first control edge 94 of the first recess 82, wherein said orifice narrows the flow cross-section to and from the one hydraulic accumulator 98 that is connected to the one suspension cylinder 108 via the orifice in a fluid-conveying manner. Likewise, viewed in the axial direction, the full diameter 76 of the valve piston 26 between the second recess 84 and third recess 86 is slightly offset from the guide part 128 between the third control chamber 118 and the fourth control chamber 120 in the direction of the insert 48, which guide part 128 is located in the area of the sloping side wall 90 of the third recess 86. As a result, this guide part 128 forms a further orifice with the adjacent first control edge 94 of the third recess 86, wherein said orifice narrows the flow cross-section to and from the further hydraulic accumulator 100 that is connected to the other suspension cylinder 110 via the further orifice in a fluid-conveying manner. The orifice and the further orifice have a damping effect in the respective fluid connection. In addition, the guide part 126 between the second control chamber 116 and the third control chamber 118 is in leading contact, viewed in the axial direction, with the full outer diameter 76 of the valve piston 26 between the first recess 82 and second recess 84. As a result, the fluid-conveying connection between one hydraulic accumulator 98 and one suspension cylinder 108 is separated from the further fluid-conveying connection between the other hydraulic accumulator 100 and the other suspension cylinder 110. This activates proportional damping of the suspension while axle oscillation is blocked.
An adjustable stop device (not shown in the figures) for the valve piston 26 may be provided in the drive housing 132 to limit the maximum stroke of the valve piston 26. In addition, control grooves (not shown in the figures) can be inserted in the areas where the outer circumference of the valve piston has its full outer diameter 76, which control grooves extend away from its respective recess 82, 84, 86 in the axial direction, in particular tapering in a wedge shape. Such a stop device and such control grooves are known from the prior art. In this regard, reference is made to DE 10 2017 004 531 A1.
In the second exemplary embodiment, the valve housing 24 has two additional fluid ports 174, 176 that can be controlled by the valve piston 26. The piston end of one suspension cylinder 108 is connected to the one additional fluid port 174 via a fifth fluid line 176, and the piston end of the other suspension cylinder 110 is connected to the other additional fluid port 178 via a sixth fluid line 180. In its first, its second and its third functional positions, the valve piston 26 connects the two additional fluid ports 174, 178 with each other, whereas in its fourth and its fifth functional positions, the valve piston 26 separates the two additional fluid ports 174, 178.
The fluid-conveying connection or separation between the additional fluid ports 174, 178 of the second exemplary embodiment established by means of the valve piston 26 in this way replaces the fluid-conveying connection between the one hydraulic accumulator 98 and the other hydraulic accumulator 100 or between the one suspension cylinder 108 and the other suspension cylinder 110 of the first exemplary embodiment. With respect to the fluid-conveying connection between the one hydraulic accumulator 98 and the one suspension cylinder 108, and the further fluid-conveying connection between the other hydraulic accumulator 100 and the other suspension cylinder 110, the functional positions of the second exemplary embodiment are identical to those of the first embodiment.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 001 713.4 | Mar 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/054449 | 2/23/2021 | WO |
