DE102020125331A1 - Actuator and method for limiting the travel of a push rod - Google Patents

Abstract

The invention relates to an actuator (1) for the rear-axle steering (2) of a motor vehicle, comprising a housing (3), a push rod (4) mounted to be axially displaceable within the housing (3), a free axial end of the push rod (4) trained or connected connection element (5) for the connection to a chassis control arm of the motor vehicle, between the connection element (5) and the housing (3) designed stop means (6) for limiting the displacement path of the push rod (4), and with the push rod (4th ) operatively connected drive motor (7) for generating a drive force to move the push rod (4) along an axial thrust axis (X). According to the invention, the stop means (6) are designed to be adjustable, so that the stop means (6) can be positioned and fixed within a positioning range (x) in or on the housing (3).

Description

The present invention relates to an actuator for the rear axle steering of a motor vehicle. The actuator comprises a housing, a push rod mounted so as to be axially displaceable within the housing, and a connection element formed or connected to a free axial end of the push rod for connection to a chassis arm of the motor vehicle. In addition, the actuator comprises stop means formed between the connection element and the housing to limit the displacement path of the push rod and a drive motor operatively connected to the push rod to generate a drive force in order to move the push rod along an axial push axis. In addition, the invention relates to a method for limiting the adjustment path of a connecting rod.

In today's actuators of rear-axle steering (rear-axle steering actuators), the end stop for the connecting rod is usually solved by software. Approaching a mechanical end stop is generally avoided in order to prevent a spindle gear which drives the push rod and is generally self-locking from getting stuck.

From the DE 10 2017 129 103 A1 a rear-axle steering system for a motor vehicle is known, which comprises an actuator with a housing, a push rod being slidably mounted in the housing. The push rod is connected to a connecting element for a chassis link in such a way that the displacement range of the push rod is limited by a stop formed between the connecting element and the housing. Also provided is a spacer that can be inserted between a guide section of the housing and the connection element and serves to limit the displacement range, so that the use of different spacers means that a chassis actuator of a specific design can be used for different vehicle types.

The invention is based on the object of providing an actuator for the rear-axle steering, each limited to a specific type of motor vehicle, which is optimized with regard to a predetermined end position or a predetermined end stop. In addition, the invention is based on the object of providing a method for limiting the adjustment path of a push rod of a rear steering actuator, as a result of which the setting of a predetermined end position or a predetermined end stop is optimized.

This object is achieved by an actuator having the features of patent claim 1. An actuator according to the invention for the rear axle steering (rear axle steering actuator) for a motor vehicle comprises a housing, a push rod mounted so as to be axially displaceable within the housing and a formed or at a free axial end of the push rod connected connection element for connection to a chassis arm of the motor vehicle. In addition, the rear-axle steering actuator comprises stop means (so-called end stop means or end stops) formed between the connection element and the housing to limit the displacement path of the push rod and a drive motor that is operatively connected to the push rod to generate a drive force in order to move the push rod along an axial push axis. According to the invention, the stop means are designed to be adjustable, such that the stop means can be positioned and fixed within a positioning range in or on the housing. This is done by either making the distance between the fork and the stop on the housing adjustable or adjustable, or by providing the fork with an adjustable counter-stop at another point instead of the stop on the housing. Positionable within the meaning of the invention is understood to mean that separate stop means are provided, which can be freely positioned and then fixed as part of the assembly of the rear axle steering actuator, so that a desired axial end stop position of the connection element (usually referred to as a fastening or push rod fork) is free is adjustable. This has the advantage that the end stops for the fastening forks of the connecting rod can be adjusted with high precision using purely mechanical means. Especially in combination with rotary linear gears, which reliably prevent an actuating gear of the connecting rod from getting stuck in a mechanical end stop position - such as a so-called planetary screw drive - considerably faster adjustment speeds near the end positions can be made possible without further technical risks.

Further advantageous refinements of the invention are specified in the dependently formulated claims. The features listed individually in the dependent claims can be combined with one another in a technologically meaningful manner and can define further refinements of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, with further preferred configurations of the invention being presented.

According to an advantageous embodiment of the invention, it can be provided that the stop means are designed in one piece and include a stop ring or that the stop means are designed in two parts and include a stop ring and a spacer ring. By using a separate component in the form of a stop ring, an adjustable (freely positionable in the axial position) end stop can be provided independently of the axial ends of the housing of the rear axle steering actuator. By using an additional spacer ring, a uniform stop ring (which is more expensive to produce) can be used and the axial length can be realized by different spacer rings.

According to a further preferred further development of the invention, it can also be provided that the stop ring has an external thread and is designed as a stop means that can be screwed into the housing. The housing preferably has an internally threaded section at its free open end, with a spacer ring designed as a lock ring with an external thread being arranged between the end of the internally threaded section axially inward in the housing and the screwed-in stop ring. Alternatively, the stop ring can also be screwed into the housing opening with a self-tapping external thread - in which case the counter ring would be omitted in this version. In this way, a highly precise setting and fixing of an end stop can be achieved with structurally simple means.

According to a further particularly preferred embodiment of the invention, it can be provided that the stop ring is designed as a sleeve that can be pressed into the housing. This provides a more structurally simplified solution for the high-precision setting of an end stop, with later readjustment being more difficult.

Furthermore, the invention can also be further developed in such a way that the housing has a receiving section on the inside at its free open end for receiving the stop means, with a pressed-in spacer ring being arranged between the end of the receiving section lying axially in the housing and a pressed-in stop ring, which is located in the Inside the housing, on its side facing away from the stop ring, is supported against an annular step that reduces the diameter of the receiving section. By introducing such an annular step, the stop ring or the spacer ring can be securely supported against an axial mechanical limitation. Unintentional adjustment of the set end stop position can thus be safely avoided.

In a likewise preferred embodiment variant of the invention, it can also be provided that the stop ring has an internal thread and is designed as a stop means that can be screwed onto the housing, so that a constructive alternative to the inner end stops described above is provided. Depending on the application and use of the rear axle steering actuator, this can be advantageous. In addition, such a configuration is very easy to assemble as far as setting the end stop position during production or a later adjustment is concerned.

It can also be advantageous to further develop the invention in such a way that the housing has an externally threaded section at its free open end on its outer lateral surface, with a spacer ring designed as a lock ring with an internal thread being arranged between the end of the externally threaded section facing away from the connection element and the screwed-on stop ring . The advantage that can be realized in this way is that the lock ring screwed on to the outside ensures a secure fixation, which allows very short adjustment times for setting and fixing the end stop position, which is extremely easy to assemble.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that a planetary roller screw drive that is operatively connected or coupled to the push rod is provided for driving the push rod. In this way it can be achieved that an unintentional jamming of the connecting rod drive in an end stop position that has been reached can be reliably prevented.

• - Bereitstellen des vormontierten Aktuators umfassend ein Gehäuse, eine innerhalb des Gehäuses axial verschiebbar gelagerte Schubstange, ein an einem freien axialen Ende der Schubstange ausgebildetes oder angebundenes Anbindungselement für die Anbindung an einen Fahrwerkslenker des Kraftfahrzeugs, zwischen dem Anbindungselement und dem Gehäuse angeordnete Anschlagmittel zur Begrenzung des Verschiebewegs der Schubstange, sowie einen mit der Schubstange wirkverbundenen Antriebsmotor zur Erzeugung einer Antriebskraft, um die Schubstange entlang einer axialen Schubachse zu bewegen, und
• - Einstellung einer mechanischen Endanschlagposition durch axiale Positionierung und Fixierung der Anschlagmittel. Bezüglich der sich ergebenden Vorteile im Rahmen des Verfahrens wird auf die vorstehenden Vorteile der korrespondierenden Vorrichtung verwiesen.

In addition, the object on which the invention is based is achieved by a method with the features of independent claim 10. A method according to the invention for limiting the adjustment path of a push rod of an actuator for a rear-axle steering system of a motor vehicle comprises the following method steps:

• - Provision of the preassembled actuator comprising a housing, a push rod mounted so as to be axially displaceable within the housing, a connection element formed or connected to a free axial end of the push rod for connection to a chassis control arm of the motor vehicle, stop means arranged between the connection element and the housing for limiting the displacement of the thrust rod, and a drive motor operatively connected to the push rod for generating a driving force to move the push rod along an axial thrust axis, and
• - Adjustment of a mechanical end stop position by axial positioning and fixing of the slings. With regard to the resulting advantages within the framework of the method, reference is made to the above advantages of the corresponding device.

The stop means in the form of a stop ring are advantageously introduced and fixed inside the housing in the area of the free axial end of the housing, or they are applied and fixed on a lateral surface outside of the housing and on the housing itself.

For this purpose it can be provided that the stop ring is pressed into the housing, or that the stop ring has an external thread through which it is screwed into the housing, or the stop ring has an internal thread through which it is screwed onto the outside of the housing.

According to a further particularly preferred embodiment of the invention, it can be provided that a spacer ring is arranged between the housing and the stop ring.

Furthermore, the invention can also be further developed such that a spacer ring designed as a lock ring that can be screwed is screwed in between the housing and the stop ring. The "distance" for the axial positioning of the stop ring is not provided by the axial length of the spacer ring, but rather by the fact that the stop ring screwed on or in is fixed by the spacer ring like a lock nut. Alternatively, the stop ring can also be equipped with a self-locking thread. Threads with locking rings in the form of plastic ring inserts or correspondingly modified metallic thread structures are known for this purpose.

In a likewise preferred embodiment variant of the invention, it can also be provided that the stop ring is pressed onto the outer circumference of the housing. As an alternative to this, the stop ring can have an internal thread, via which it is screwed onto the outer circumference of the housing, it being advantageously fixed on the outer circumference of the housing by means of a spacer ring designed as a lock ring that can be screwed on.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention should not be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description and/or figures. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. The same reference symbols designate the same objects, so that explanations from other figures can be used as a supplement if necessary.

• 1 einen Hinterachslenkungsaktuator in einer Perspektivansicht in schematischer Darstellung,
• 2 einen Teilausschnitt des in 1 dargestellten Hinterachslenkungsaktuators in einer ersten möglichen Ausführungsform der Erfindung, in einem axialen Teilschnitt in schematischer Darstellung,
• 3 einen Teilausschnitt des in 1 dargestellten Hinterachslenkungsaktuators in einer zweiten möglichen Ausführungsform der Erfindung, in einem axialen Teilschnitt in schematischer Darstellung, und
• 4 einen Teilausschnitt des in 1 dargestellten Hinterachslenkungsaktuators in einer dritten möglichen Ausführungsform der Erfindung, in einem axialen Teilschnitt in schematischer Darstellung.

Show it:

• 1 a rear axle steering actuator in a perspective view in a schematic representation,
• 2 a partial section of the in 1 illustrated rear axle steering actuator in a first possible embodiment of the invention, in an axial partial section in a schematic representation,
• 3 a partial section of the in 1 illustrated rear axle steering actuator in a second possible embodiment of the invention, in an axial partial section in a schematic representation, and
• 4 a partial section of the in 1 illustrated rear axle steering actuator in a third possible embodiment of the invention, in an axial partial section in a schematic representation.

1 shows a rear axle steering actuator 1 in a perspective view in a schematic representation. The illustrated actuator 1 for the rear axle steering 2 of a motor vehicle comprises a housing 3, a push rod 4 which is mounted so as to be axially displaceable within the housing 3 (see FIG 2 ) and a connecting element 5 formed or connected to a free axial end of the push rod 4 in the form of a push rod or fastening fork for the connection to a chassis arm of the motor vehicle. In addition, stop means 6 are provided between the connecting element 5 and the housing 3 to limit the displacement path of the push rod 4, and the rear axle steering actuator 1 also includes a drive motor 7, which is operatively connected to the push rod 4, to generate a driving force to move the push rod 4 along an axial thrust axis X to move. The drive motor 7 is followed by two gears 8, 9 connected in series. Through the first gear 8, the rotation of the shaft of the drive motor 7 is converted into a rotation of another element within the actuator 1. In the present case, the first transmission 8 (a rotary-rotary transmission) is a belt transmission in the form of a belt drive. The second gear 9 downstream of the first gear 8 is designed as a rotary-linear gear, namely a screw drive. In the exemplary embodiment, the second gear 9 is designed as a planetary roller screw drive (PWG).

the following one 2-4 has in common that in each case an axial end area of the rear axle steering actuator 1 is shown in a partial axial section, with the stop means 6 being shown as they are positioned and fastened in the housing 3 and how they interact with a connecting element 5 designed as a fastening fork. The stop means 6 are “adjustable” or designed so that they can be freely positioned and fixed in their axial position within an adjustment range. In the illustrated embodiments, the stop means 6 are each formed in two parts and comprise a stop ring 61 and a spacer ring 62. The stop ring 61 forms a first stop surface A1 with its annular surface pointing in the direction of the connection element 5, which is connected to a surface formed by the connection means 5 or attached or formed on the connection element 5 second stop surface A2 interacts to limit travel.

According to the embodiments of 2 and 3 the connection element 5 has an annular extension with a reduced diameter, which forms the stop surface A2 on its annular surface facing the stop ring 61 . The diameter of the annular extension is dimensioned smaller than the enlarged inner diameter of the housing 3.
In the embodiment according to 4 the stop surface A2, on the other hand, is formed directly by a circular ring-shaped part of the flat bottom surface of the connection element 5 facing the stop ring 61 - here the connection element 5 in the end stop position does not protrude in some areas into the housing 3, but is supported outside the housing 3 on the spacer ring 61.

2 shows a partial section of the in 1 illustrated rear axle steering actuator 1 in a first possible embodiment of the invention, in an axial partial section in a schematic representation. The housing 3 is in its axial end region, internally expanded over an axial length l in the inside diameter, to accommodate a spacer ring 62 and a stop ring 61 . In the example shown, the spacer ring 62 is inserted into the receiving area, which has an enlarged diameter, and is supported against an annular step 33 (limiting the axial path). A stop ring 61 is then pressed into the receiving area until it rests against the spacer ring 62 and reaches its end position. 2 shows a way of not placing the counter-stop for the fork on the housing 3 itself, in order to avoid any subsequent part variance. For this purpose, a separate component (here: pressed-in stop ring 61) is introduced into the housing 3 in the example, which is pressed into the housing 3, for example, and its end position in the axial pressing-in direction during the pressing-in process via an element located behind it (here a spacer ring 62) for tolerance compensation is defined. The stop ring 61 interacts with its stop surface A1 with the circular stop surface A2 facing it of a circular ring-shaped section of the connection element 5 with a reduced diameter in a travel-limiting manner. The stop ring 61 together with the spacer ring 62 thus provides an adjustable stop surface for tolerance compensation, via which the mechanically available steering stroke can be limited/or increased. can be adjusted very precisely.

In addition to the axial stop, this stop ring can also take over a radial bearing of the steering linkage or also additional sealing functions for the actuator (not explicitly shown here). Such functional integration represents a very space-saving and very advantageous embodiment of the solution.

3 also shows a partial section of the in 1 illustrated rear axle steering actuator - here in a second possible embodiment of the invention -, in an axial partial section in a schematic representation. In this embodiment, the stop ring 61 has an external thread and is designed as a stop means 6 that can be screwed into the housing 3 .

Like in the 3 shown, the housing 3 has an internally threaded section 31 at its free, open end, with a spacer ring 62 designed as a lock ring with an external thread being arranged between the end of the internally threaded section 31 that is axially inward in the housing 3 and the screwed-in stop ring 61. Here, too, the inner stop ring 61 with its stop surface A1 acts together with the circular stop surface A2 facing it of a circular section of the connection element 5 with a reduced diameter, limiting the travel.

4 shows a partial section of the in 1 illustrated rear axle steering actuator 1 in a third possible embodiment of the invention, in an axial partial section in a schematic representation. This figure clearly shows that the stop ring 61 has an internal thread and is designed as a stop means 6 that can be screwed onto the housing 3 . The housing 3 has a corresponding externally threaded section 35 on its free, open end on its outer lateral surface, with a spacer ring 62 designed as a lock ring with an internal thread being arranged between the end of the externally threaded section 35 facing away from the connection element 5 and the screwed-on stop ring 61.

• Hier wird in beiden Lösungen ein Anschlagsring 61 in ein oder auf ein im bzw. am Gehäuse 3 befindliches Gewinde ein- bzw. aufgeschraubt, welcher dann in seiner axialen Lage durch eine Rotation um die Gewindeachse sehr genau positioniert werden kann. Der wesentliche Unterschied zwischen den beiden Lösungen ist, dass die Lösung gemäß 3 einen Anschlagsring 61 mit Außengewinde in einem gehäuseseitigem Innengewinde vorschlägt, wobei das Anbindungselement 5 in einer Endanschlagposition mit einem im Durchmesser reduzierten kreisringförmigen Fortsatz in das Gehäuse 3 hineinragt und dort wegbegrenzend mit dem Anschlagring 61 zusammenwirkt, während die Lösung gemäß 4 genau andersherum eine Lösung mit Anschlagsring 61 mit Innengewinde in einem gehäuseseitigem Außengewinde aufzeigt, wobei der Anschlag in einer Endanschlagposition zwischen Anschlagring 61 und Anbindungselement 5 außerhalb des Gehäuses 3 stattfindet. In beiden Lösungen wird dieser auf- bzw. eingeschraubte Anschlagsring 61 über einen zweiten Gewindering (Distanzring 62) axial fixiert/gesichert, in dem der zweite Ring gegen den ersten Anschlagsring 61 in seiner Endlage verschraubt und damit gekontert wird. Beide Male bildet der Anschlagsring 61 eine einstellbare Gegen-Anschlagsfläche für das gabelartige Anbindungselement 5, was letztlich zu einer Einschränkung des verfügbaren Stellwegs bzw. des verbleibenden Stellbereichs führt. In beiden Lösungen gibt es wieder die Möglichkeit, eine besonders vorteilhafte Ausgestaltung zu erreichen, indem der Anschlagsring 61 neben der Begrenzung des Stellwegs auch eine radiale Lagerung der Schubstange 4 oder auch zusätzlich Dichtungsfunktionen für den Aktuator übernimmt.

The embodiments according to 3 and 4 show another way to limit the available adjustment range of a rear axle steering actuator 1 via mechanical end stops 6 that can be adjusted on both sides:

• In both solutions, a stop ring 61 is screwed into or onto a thread located in or on the housing 3, which can then be positioned very precisely in its axial position by rotating about the thread axis. The main difference between the two solutions is that according to the solution 3 proposes a stop ring 61 with an external thread in an internal thread on the housing, with the connection element 5 protruding in an end stop position with a circular extension of reduced diameter into the housing 3 and there interacting with the stop ring 61 to limit travel, while the solution according to 4 exactly the other way around shows a solution with a stop ring 61 with an internal thread in an external thread on the housing, the stop taking place in an end stop position between the stop ring 61 and the connection element 5 outside the housing 3 . In both solutions, this screwed-on or screwed-in stop ring 61 is axially fixed/secured via a second threaded ring (spacer ring 62), in which the second ring is screwed against the first stop ring 61 in its end position and thus countered. In both cases, the stop ring 61 forms an adjustable counter-stop surface for the fork-like connection element 5, which ultimately leads to a limitation of the available adjustment path or the remaining adjustment range. In both solutions, there is again the possibility of achieving a particularly advantageous embodiment in that the stop ring 61 not only limits the adjustment travel but also assumes a radial bearing of the push rod 4 or also additional sealing functions for the actuator.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

Reference List

1

actuator

2

rear axle steering

3

housing

4

push rod

5

connection element

6

slings

7

drive motor

31

female thread section

32

recording section

33

ring level

35

male thread section

61

stop ring

62

spacer ring

X

thrust axis

I

axial length (inner diameter)

A1

stop surface (spacer ring)

A2

Stop surface (connecting element)

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102017129103 A1 [0003]

Claims (18)

Actuator (1) for the rear-axle steering (2) of a motor vehicle, comprising - a housing (3), - a push rod (4) mounted so as to be axially displaceable within the housing (3), - a push rod (4) formed at a free axial end of the push rod (4). or connected connection element (5) for connection to a chassis link of the motor vehicle, - stop means (6) formed between the connection element (5) and the housing (3) for limiting the displacement path of the connecting rod (4), and - a connecting element ( 4) operatively connected drive motor (7) for generating a drive force in order to move the push rod (4) along an axial push axis (X), characterized in that the stop means (6) are adjustable, such that the stop means (6) within a positioning area (x) can be positioned and fixed in or on the housing (3). actuator (1) after claim 1 , characterized in that the stop means (6) are formed in one piece and include a stop ring (61) or that the stop means (6) are formed in two parts and include a stop ring (61) and a spacer ring (62). Actuator (1) according to one of the preceding claims, characterized in that the stop ring (61) has an external thread and is designed as a stop means (6) which can be screwed into the housing (3). actuator (1) after claim 3 , characterized in that the housing (3) has an internally threaded section (31) at its free, open end, with a counter-ring with Externally threaded spacer ring (62) is arranged. Actuator (1) according to any one of the preceding Claims 1 - 2 , characterized in that the stop ring (61) is designed as a sleeve which can be pressed into the housing (3). actuator (1) after claim 5 , characterized in that the housing (3) has a receiving section (32) on the inside at its free open end for receiving the stop means (6), with the end of the receiving section (32) lying axially inside the housing (3) and a pressed-in stop ring (61) a pressed-in spacer ring (62) is arranged, which is supported inside the housing on its side facing away from the stop ring (61) against an annular step (33) reducing the diameter of the receiving section (32). Actuator (1) according to any one of the preceding Claims 1 - 2 , characterized in that the stop ring (61) has an internal thread and is designed as a stop means (6) which can be screwed onto the housing (3). actuator (1) after claim 7 , characterized in that the housing (3) has an externally threaded section (35) on its free, open end on its outer lateral surface, with a spacer ring (62) designed as a counter ring with an internal thread. Actuator (1) according to one of the preceding claims, characterized in that a planetary screw drive which is operatively connected/coupled to the push rod (4) is provided for driving the push rod. Method for limiting the adjustment path of a push rod (4) of an actuator (1) for a rear-axle steering (2) of a motor vehicle, comprising the following method steps: - Providing the preassembled actuator (1) comprising - a housing (3), - a push rod (4) mounted to be axially displaceable within the housing (3), - a connection element (5) formed or connected to a free axial end of the push rod (4) for connection to a chassis control arm of the motor vehicle, - Stop means (6) arranged between the connecting element (5) and the housing (3) for limiting the displacement path of the connecting rod (4), and - a drive motor (7) operatively connected to the push rod (4) for generating a driving force to move the push rod (4) along an axial push axis (X), and - Setting a mechanical end stop position () by axially positioning and fixing the stop means (6). procedure after claim 10 , characterized in that in the area of the free axial end of the housing (3), within the housing (3), the stop means (6) are introduced and fixed in the form of a stop ring (61) or on a lateral surface outside the housing (3) and applied and fixed on the housing (3) itself. procedure after claim 11 , characterized in that the stop ring (61) is pressed into the housing (3). procedure after claim 11 , characterized in that the stop ring (61) has an external thread through which it is screwed into the housing (3). Procedure according to one of Claims 11 - 13 , characterized in that a spacer ring (62) is arranged between the housing (3) and the stop ring (61). procedure after Claim 14 , characterized in that between the housing (3) and the stop ring (61) designed as a lock ring screwable spacer ring (62) is screwed. procedure after claim 11 , characterized in that the stop ring (61) is pressed onto the outer circumference of the housing (3). procedure after claim 11 , characterized in that the stop ring (61) has an internal thread, via which it is screwed onto the outer circumference of the housing (3). procedure after Claim 17 , characterized in that the stop ring (61) is fixed on the outer circumference of the housing (3) by means of a lock ring designed as a screwable spacer ring (62).

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