DE102017107994A1 - Motor vehicle chassis - Google Patents

Abstract

The hydraulic level adjusting device associated with a wheel suspension of a motor vehicle chassis comprises a hydraulic fluid reservoir (1), a reversible hydraulic power pack (2) with a hydraulic pump (6) and a single-acting hydraulic linear actuator (7). The working space (12) of the linear actuator (7) can be acted upon by the hydraulic pump (6) via a filling line (13) with a filling check valve (14) arranged therein. The second pump connection (5) is connected via a first control line (25) to a control pressure connection (26) of a hydraulically actuated valve arrangement, which upon pressurization of the control pressure port (26) a Rückströmweg from the working space (12) of the linear actuator (7) to the reservoir (1) opens. Another control pressure connection (31) of the valve arrangement is connected via a further control line (30) to the first pump connection (4). The hydraulically actuated valve arrangement has an inherently stable switching state with an open return flow path from the working space (12) of the linear actuator (7) to the reservoir (1). The Rückströmweg from the working space (12) of the linear actuator (7) to the reservoir (1) is closed only by pressurization of the other control pressure port (31).

Description

The present invention relates to a motor vehicle chassis comprising a base structure and a plurality of wheels connected thereto via a respective wheel suspension, wherein at least one wheel suspension is associated with a hydraulic level adjustment device. In particular, the present invention relates to a motor vehicle chassis specified in the preamble of claim 1 Art.

Automotive chassis with the wheels associated hydraulic level adjustment devices count in various configurations of the prior art. They are known for example from the WO 2014/142160 A1 . WO 2012/061127 A1 . JP 2007-38791 A . JP 2007-30665 A . JP 2009-126455 A . JP 2006-213119 A . DE 3223195 A1 and DE 102014018788 B3 ,

The last mentioned DE 102014018788 B3 discloses a motor vehicle chassis of the generic, specified in the preamble of claim 1. Art is particularly characteristic of the case realized hydraulic level adjustment, that in each case the second pump connection of the reversible hydraulic unit, ie the other than that which for the lifting of the chassis is acted upon via a filling line to the working space of the linear actuator, via a control line to a control pressure port of a hydraulically actuated valve assembly is in communication, which opens a Rückströmweg from the working space of the linear actuator to the reservoir on pressurization of the control pressure port. Compared with previously known motor vehicle chassis with the wheels associated hydraulic level adjustment, the one characterized by this publication by a particularly compact design of the hydraulic level adjustment, so that this is best for a decentralized arrangement directly to the respective suspension ,

With regard to the actual function, namely the reliable raising and lowering of the chassis (or its basic structure) by compact hydraulic level adjustment, systems such as the DE 102014018788 B3 proven in principle. However, the noise emitted when modifying the chassis level by the hydraulic unit is perceived as disturbing, in particular for vehicles from the premium segment.

The present invention has thus set itself the task of providing a motor vehicle chassis of the generic type, which is characterized by a reduced noise emission - especially when lowering the chassis.

This object is achieved according to the present invention by in a motor vehicle chassis of the generic type - the second pump connection to a control pressure port of a hydraulically actuated valve assembly - connecting control line is a first control line and the hydraulically actuated valve assembly comprises at least one further control pressure port, the over a further control line communicates with the first pump connection, wherein the hydraulically actuated valve arrangement does not require a pumping mode intrinsically stable switching state with open Rückströmweg from the working space of the linear actuator to the reservoir and the Rückströmweg closed from the working space of the linear actuator to the reservoir only by pressurizing the other control pressure port becomes. In the motor vehicle chassis according to the invention thus exists, in other words, one of the other synergistically functionally cooperating with the other characteristics in the fact that both pump outputs via associated control lines to the hydraulically actuated, bistable executed valve arrangement act, so that - depending on the conveying direction of the Hydraulic unit - two different hydraulic pulses for switching the bistable hydraulically actuated valve assembly can each be used from a switching position in the other switching position.

As a result, it can be achieved, in particular, that prolonged operation of the hydraulic unit is not necessary for lowering the basic structure of the motor vehicle chassis. Rather, it is sufficient both to initiate the lowering and to terminate this, in each case only a short pressure pulse by briefly starting the hydraulic unit. In implementation of the present invention thus eliminates a - by vehicle occupants and / or outsiders - as disturbing perceived noise (hum) of the hydraulic unit when lowering the chassis.

According to a first preferred embodiment of the invention, the filling check valve is designed hydraulically unlockable and forms such a part of the hydraulically actuated valve arrangement, that the first control line is connected to its control pressure port. Particularly in such an embodiment, a further hydraulically releasable check valve is particularly preferably arranged in the first control line, at its control pressure connection the further, with the first pump connection communicating control line is connected. Thus, the control pressure by which the hydraulically releasable filling check valve can be opened, effectively be locked so long until a hydraulic pulse from the first pump port, the further hydraulically releasable check valve is opened and the control pressure collapses.

In this case, in a particularly preferred manner, in particular to the second pump connection or the first control line between the second pump connection and the further hydraulically releasable check valve, a pressure relief line terminating in the reservoir can be connected to a pressure relief valve. This reduces the risk of damage to the hydraulic system due to an overpressure situation. In another preferred development, a pressure compensator is connected in the pressure relief line in such a way that the first pump connection also communicates with the reservoir via the pressure relief valve.

Preferably, in motor vehicle chassis according to the invention, the second pump connection is connected to the reservoir via a non-return valve, specifically with a direction of flow from the reservoir to the second pump connection. This has a favorable effect on the provision of the above-described, the lowering of the chassis preliminary hydraulic pulse by briefly starting the hydraulic unit with the conveying direction from the first to the second pump port.

It is also advantageous if between the reservoir and the first pump port, a hydraulically actuated check valve is connected, which forms part of the hydraulically actuated valve arrangement such that the first control line is connected to its control pressure port. A particular advantage of this development of the invention is the favorable effects on the provision of the hydraulic pulse described above, the lowering of the chassis terminating by brief start of the hydraulic unit with conveying direction from the second to the first pump connection.

According to an alternative preferred embodiment of the invention, the two pump ports are connected via a shuttle valve to the reservoir and the second pump port is additionally connected via a throttle unit to the reservoir. In particular, in a particularly preferred embodiment, the hydraulically actuated valve arrangement comprises a bistable 2/2-way valve which is hydraulically actuated via the first and the second control pressure connection and arranged in a discharge line connecting the working space of the linear actuator to the second pump connection and / or directly to the reservoir , This training comes with a single hydraulically controlled valve. This makes it possible to realize particularly compact systems.

In another preferred development, an outflow throttle can be arranged in the outflow line. This is advantageous in that, by adapting the outflow throttle to the respective vehicle, the system can be set to different vehicles with the least possible effort. It is particularly favorable if a pressure relief line ending in the reservoir is connected to a pressure limiting valve at the first pump connection. This in turn reduces the risk of damage to the hydraulic system due to an overpressure situation.

• 1 den hydraulischen Schaltplan eines ersten Ausführungsbeispiels einer bei einem erfindungsgemäßen Kraftfahrzeug-Fahrgestell einsetzbaren hydraulischen Niveau-Verstelleinrichtung,
• 2 den hydraulischen Schaltplan eines abgewandelten, zweiten Ausführungsbeispiels einer bei einem erfindungsgemäßen Kraftfahrzeug-Fahrgestell einsetzbaren hydraulischen Niveau-Verstelleinrichtung 3 den hydraulischen Schaltplan eines dritten Ausführungsbeispiels einer bei einem erfindungsgemäßen Kraftfahrzeug-Fahrgestell einsetzbaren hydraulischen Niveau-Verstelleinrichtung und
• 4 den hydraulischen Schaltplan eines abgewandelten, vierten Ausführungsbeispiels einer bei einem erfindungsgemäßen Kraftfahrzeug-Fahrgestell einsetzbaren hydraulischen Niveau-Verstelleinrichtung.

In the following, the present invention will be explained with reference to several embodiments illustrated in the drawings. It shows

• 1 2 is the hydraulic circuit diagram of a first exemplary embodiment of a hydraulic level adjustment device which can be used in a motor vehicle chassis according to the invention;
• 2 the hydraulic circuit diagram of a modified, second embodiment of a usable in a motor vehicle chassis according to the invention hydraulic level adjustment 3 the hydraulic circuit diagram of a third embodiment of a usable in a motor vehicle chassis according to the invention hydraulic level adjustment and
• 4 the hydraulic circuit diagram of a modified, fourth embodiment of a usable in a motor vehicle chassis according to the invention hydraulic level adjustment.

After the motor vehicle chassis referred to in the drawings illustrated embodiments, apart from the specific design of the respective hydraulic level adjustment in the usual, as such (for example, from DE 102014018788 B3 ) known manner - with basic structure and suspension with wheels - may be executed, is omitted on the graphic representation of other details of the motor vehicle chassis and their explanation. Thus, with reference to FIGS 1 to 4 , received solely on the respective hydraulic level adjustment.

After the in 1 shown in the first embodiment, each of the individual wheel suspensions associated hydraulic level adjustment means comprises a reservoir 1 for hydraulic fluid, a hydraulic power unit 2 with two pump ports driven by an electric motor (not shown) 4 . 5 having hydraulic pump 6 , a hydraulic linear actuator 7 and a reservoir 1 , the hydraulic pump 6 and the linear actuator 7 interconnecting line and valve assembly 8th , The (schematically as a cylinder-piston arrangement with a cylinder 9 and a piston 10 shown) linear actuator 7 In this case, it is designed to have a simple effect in the sense that only one of its two hydraulic chambers can be actively acted upon, namely the one caused by the load 11 (Base structure), for lifting the base structure by the hydraulic pump 6 actable work space 12 , This is the first pump connection 4 via a filling line 13 with a (hydraulically releasable, see below) filling check valve 14 with the workspace 12 of the hydraulic linear actuator 7 connected. The other hydraulic room 15 meanwhile, it is permanently depressurised, passing through the equalization line 16 with the reservoir 1 communicates.

In order to raise the basic structure of the motor vehicle chassis, the hydraulic power unit 2 with a delivery direction from the second pump port 5 to the first pump connection 4 operated, so is hydraulic fluid through the filter 17 and the check valve 18 from the reservoir 1 sucked in and over the filling line 13 into which a first throttle 19 , a calming chamber 20 , a second throttle 21 , the filling check valve 14 and a filter 22 are integrated into the workspace 12 promoted. The connection line 23 the calming chamber 20 to the reservoir 1 is via the (hydraulically releasable, see below) check valve 24 blocked. When the basic structure of the motor vehicle chassis reaches its desired level, the hydraulic power unit stops 2 , The one in the workroom 12 existing hydraulic fluid is there via the filling check valve 14 locked so that the basic structure of the motor vehicle chassis remains at the set level.

To lower the basic structure of the motor vehicle chassis, the reversible hydraulic unit 2 briefly with reverse flow direction, ie with a delivery direction from the first pump port 4 to the second pump connection 5 operated. The suction side, hydraulic fluid from the reservoir 1 over the connecting line 23 , the check valve 24 , the calming chamber 20 and the throttle 19 to the first pump connection 4 reach. On the pressure side, the check valve locks 18 so that from the second pump port 5 via the first control line connected to it 25 the control pressure connection 26 the hydraulically releasable filling check valve 14 is charged. About the from the first control line 25 branching branch line 27 at the same time becomes the control pressure connection 28 the hydraulically operated check valve 24 applied. This simultaneously open the filling check valve 14 as well as the check valve 24 , so that - under the action of the load 11 - Hydraulic fluid from the work area 12 over the filling line 13 and the (open) check valve 24 in the reservoir 1 is displaced.

That in the first control line 25 integrated (hydraulically releasable; see below) non-return valve 29 holds the at the two control pressure connections 26 and 28 adjacent control pressure, so even without continued operation of the hydraulic unit 2 with delivery direction from the first pump connection 4 to the second pump connection 5 the filling check valve 14 as well as the check valve 24 stay open. Just to initiate the lowering is, as stated, a brief start of the hydraulic unit required to a filling check valve 14 as well as the check valve 24 to provide opening hydraulic "impulse". The further lowering of the basic structure of the motor vehicle chassis, however, takes place without the hydraulic unit 2 to operate. Thus, the hydraulically actuated valve assembly has a pumping operation requiring intrinsically stable switching state with open Rückströmweg from the working space 12 of the linear actuator 7 to the reservoir 1 on.

Similarly, when the desired level is reached, the lowering of the base structure of the motor vehicle chassis is accomplished solely by a hydraulic pulse from the hydraulic power unit 2 (in conveying direction from the second pump connection 5 to the first pump connection 4 ) completed. Because of the throttle 19 causes a pressure increase at the first pump connection 4 via this with the control pressure connection 30 the hydraulically operated check valve 29 connecting another, second control line 31 an opening of the check valve 29 , The control pressure in the downstream branch of the control line 25 collapses. And both the filling check valve 14 as well as the check valve 24 shut down. The one in the workroom 12 existing hydraulic fluid is there via the filling check valve 14 locked so that the basic structure of the motor vehicle chassis remains at the set level.

The second, in 2 embodiment shown builds on the embodiment described above 1 on. To the extent of agreement, a further explanation is omitted. The essential modification is in the second embodiment, to the second pump port 5 or the first control line 25 between the second pump connection 5 and the (further) hydraulically releasable check valve 29 one in the reservoir 1 ending pressure relief line 32 with a pressure relief valve 33 connected. In the pressure relief line is a pressure compensator 34 integrated, whose second input - via the calming chamber 20 - with the first pump connection 4 communicated. This is how both pump connections communicate 4 and 5 via the pressure balance 34 , the pressure relief line 32 and the pressure relief valve 33 with the reservoir 1 , so that in each of the two conveying directions of the hydraulic unit 2 a pressure-related damage to the hydraulic system is excluded.

Recognizable are in 2 still an additional filter 35 between the reservoir 1 and the check valve 24 and an additional acoustic calming additional calming chamber 36 in the filling line 13 between the (first) calming chamber 20 and the throttle 21 ,

This in 3 Although shown third embodiment according to the embodiment according to 1 comparable operating behavior, but using a considerable amount of deviating constructive means. A particularly serious difference is that here, when lowering the basic structure of the motor vehicle chassis hydraulic fluid from the working space 12 of the linear actuator 7 not over the filling line 13 but rather via a discharge line 37 back to the reservoir 1 arrives. Accordingly, here is the filling check valve 38 also not run hydraulically unlockable.

In the discharge line 37 are - connected to each other in series - an outflow throttle 39 and a hydraulically operated bistable 2/2-way valve 40 integrated. A first control pressure input 41 of the bistable 2/2-way valve 40 is above the first control line 42 with the second pump connection 5 and a second control pressure input 43 of the bistable 2/2-way valve 40 is above the second control line 44 with the first pump connection 4 in connection.

The two pump connections 4 and 5 are via a shuttle valve 45 with the reservoir 1 connected. The second pump connection 5 is additionally via a throttle unit 46 with the reservoir 1 connected.

In order to raise the basic structure of the motor vehicle chassis, the hydraulic power unit 2 with a delivery direction from the second pump port 5 to the first pump connection 4 operated, so will - via the shuttle valve 45 and the second pump port 5 from the reservoir 1 sucked in - hydraulic fluid via the filling line 13 with the two calming chambers 20 and 36 , the throttle 21 , the filling check valve 38 and the filter 22 in the workroom 12 of the linear actuator 7 promoted. Over the second control line 44 acts on the first pump connection 4 prevailing pressure on the second control pressure input 43 of the bistable 2/2-way valve 40, so that this his - in 3 shown - the discharge line 37 takes a blocking position. When the basic structure of the motor vehicle chassis reaches its desired level, the hydraulic power unit stops 2 , The one in the workroom 12 existing hydraulic fluid remains there via the filling check valve 38 and the locked 2/2-way valve 40 is locked, so that the basic structure of the motor vehicle chassis remains at the set level.

To lower the basic structure of the motor vehicle chassis, the reversible hydraulic unit 2 briefly with reverse flow direction, ie with a delivery direction from the first pump port 4 to the second pump connection 5 operated. On the suction side, hydraulic fluid can be supplied via the shuttle valve 45 and the calming chamber 20 from the reservoir 1 be sucked. Because the shuttle valve 45 the unthrottled connection of the second pump connection 5 with the reservoir 1 locks and thus the second pump connection 5 just over the throttle 46 with the reservoir 1 communicates, acts on the first control pressure input 41 of the 2/2-way valve 40 in the form of a corresponding hydraulic pulse at the second pump port 5 prevailing pressure. This causes a change of the 2/2-way valve 40, so that the discharge line 37 is opened. Well - under the influence of the load 11 - Hydraulic fluid from the work area 12 via the discharge line 37 (through the throttles 39 and 46 braked) in the reservoir 1 be displaced. Just to initiate the lowering is, as stated, a short start of the hydraulic unit required to provide the 2/2-way valve 40 opening hydraulic "pulse". The further lowering of the basic structure of the motor vehicle chassis, however, takes place without the hydraulic unit 2 to operate. Thus, also here the hydraulically actuated valve arrangement has a pumping operation requiring intrinsically stable switching state with open Rückströmweg from the working space 12 of the linear actuator 7 to the reservoir 1 on.

In a corresponding manner, when the desired level is reached, the lowering of the basic structure of the motor vehicle chassis alone by a hydraulic pulse from the hydraulic power unit 2 (in conveying direction from the second pump connection 5 to the first pump connection 4 ) completed. Because as a result of the shuttle valve 45 and the throttle 21 causes a pressure increase at the first pump connection 4 via this with the second control pressure connection 43 of the 2/2-way valve 40 connecting further, second control line 44 a closing of the 2/2-way valve 40. The in the working space 12 existing hydraulic fluid is there via the filling check valve 38 and the closed 2/2-way valve 40 is locked, so that the basic structure of the motor vehicle chassis remains at the set level.

The fourth, in 4 embodiment shown builds on the embodiment described above 3 on. To the extent of agreement, a further explanation is omitted. The essential modification is that in the fourth embodiment of the first pump port 4 (or the communicating with this calming chamber 20 ) one in the reservoir 1 ending pressure relief line 47 with a pressure relief valve 48 connected.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2014/142160 A1 [0002]
• WO 2012/061127 A1 [0002]
• JP 2007038791 A [0002]
• JP 2007030665 A [0002]
• JP 2009126455 A [0002]
• JP 2006213119 A [0002]
• DE 3223195 A1 [0002]
• DE 102014018788 B3 [0002, 0003, 0004, 0015]

Claims (11)

Motor vehicle chassis comprising a base structure and a plurality of wheels connected thereto via a respective wheel suspension, wherein at least one wheel suspension is associated with a hydraulic level adjustment device, having the following features: - the hydraulic level adjustment device comprises a reservoir (1) for Hydraulic fluid, a hydraulic unit (2) having a driven by an electric motor, two pump ports (4, 5) having hydraulic pump (6), a single-acting hydraulic linear actuator (7) and a reservoir (1), the hydraulic pump (6) and the Linear actuator (7) interconnecting line and valve assembly (8); - The hydraulic unit (2) is reversible with a between the two pump ports (4, 5) reversible conveying direction; - For lifting the base structure of the working space (12) of the linear actuator (7) by the hydraulic pump (6) can be acted upon, for which purpose a first pump port (4) via a filling line (13) with a filling check valve (14; 38) is connected to the working space (12) of the hydraulic linear actuator (7); The second pump connection (5) is connected via a control line (25; 42) to a control pressure connection (26; 41) of a hydraulically actuated valve arrangement which, when pressure is applied to the control pressure connection (26; 41), forms a return flow path from the working space (12) of the Linear actuator (7) to the reservoir (1) opens; characterized in that the control line (25; 42) is a first control line and the hydraulically actuated valve arrangement comprises at least one further control pressure port (31; 43) which communicates via a further control line (30; 44) with the first pump port (4) has, wherein the hydraulically actuated valve assembly has a non-pumping requiring intrinsically stable switching state with opened Rückströmweg from the working space (12) of the linear actuator (7) to the reservoir (1) and the Rückströmweg from the working space (12) of the linear actuator (7) to the reservoir ( 1) is closed only by pressurization of the further control pressure port (31, 43). Motor vehicle chassis after Claim 1 , characterized in that the filling-check valve (14) is designed to be hydraulically releasable and forms such a part of the hydraulically actuated valve arrangement that the first control line (25) is connected to its control pressure port (26). Motor vehicle chassis after Claim 1 or Claim 2 , characterized in that in the first control line (25) in turn a further hydraulically releasable check valve (29) is arranged, at the control pressure port (31), the further control line (30) is connected. Motor vehicle chassis after Claim 3 , characterized in that at the second pump port (5) or to the first control line (25) between the second pump port (5) and the further hydraulically releasable check valve (29) in the reservoir (1) ending pressure relief line (32) with a pressure relief valve (33) is connected. Motor vehicle chassis after Claim 4 , characterized in that in the pressure relief line (32) a pressure compensator (34) is connected in such a way that also the first pump port (4) via the pressure relief valve (33) communicates with the reservoir (1). Motor vehicle chassis according to one of Claims 1 to 5 , characterized in that the second pump port (5) via a check valve (18) communicates with the reservoir Motor vehicle chassis according to one of Claims 1 to 6 , characterized in that between the reservoir (1) and the first pump port (4), a hydraulically releasable check valve (24) is connected, which forms part of the hydraulically actuated valve arrangement such that the first control line (25) at its control pressure port (28 ) connected. Motor vehicle chassis after Claim 1 , characterized in that the two pump ports (4, 5) via a shuttle valve (45) to the reservoir (1) are connected and the second pump port (5) is additionally connected via a throttle unit (46) to the reservoir (1). Motor vehicle chassis after Claim 8 , characterized in that the hydraulically actuated valve arrangement has a discharge line (37) arranged in a working space (12) of the linear actuator (7) with the second pump connection (5) and / or directly to the storage container (1), via the first control pressure connection ( 41) and the second control pressure port (43) comprises hydraulically actuated bi-stable 2/2 way valve (40). Motor vehicle chassis after Claim 9 , characterized in that in the discharge line (37) an outflow throttle (39) is arranged. Motor vehicle chassis according to one of Claims 8 to 10 , characterized in that the first pump connection (4) has a pressure relief line (47) ending in the reservoir (1) connected to a pressure limiting valve (48).

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