DE102016220967A1 - Electrohydraulic intermediate cylinder for an actuating device for actuating a motor vehicle clutch - Google Patents

Abstract

Electrohydraulic intermediate cylinder (1) for an actuating device for actuating a motor vehicle clutch, wherein the intermediate cylinder (1) is hydraulically connected to a master cylinder via a first pressure line (2) and to a slave cylinder via a second pressure line (3), comprising a cylinder housing (4) an electric motor (5), a threaded spindle (6), wherein the threaded spindle (6) is drivingly connected to the electric motor (5), and a first piston (7) and a second piston (8), wherein the first piston (7 ) and the second piston (8) within the cylinder housing (4) are arranged and by the arrangement of the first piston (7) and the second piston (8) in the cylinder housing (4) a first hydraulic chamber (9) of first hydraulic volume and forming a second hydraulic chamber (10) second hydraulic volume.

Description

Field of the invention

The present invention relates to an electro-hydraulic intermediate cylinder for an actuating device for actuating a motor vehicle clutch, wherein the intermediate cylinder is hydraulically connected via a first pressure line to a master cylinder and via a second pressure line to a slave cylinder, comprising a cylinder housing, an electric motor, a threaded spindle, wherein the threaded spindle is drivingly connected to the electric motor, and a first piston and a second piston, wherein the first piston and the second piston are disposed within the cylinder housing and by the arrangement of the first piston and the second piston in the cylinder housing, a first hydraulic chamber first hydraulic volume and form a second hydraulic chamber of second hydraulic volume.

State of the art

Conventional hydraulic actuators for motor vehicle clutches, in particular friction clutches, have a master cylinder and a slave cylinder. The master cylinder is connected to a reservoir filled with hydraulic fluid and comprises a master piston, which is acted upon by an actuating member, such as a clutch pedal, with force and displaced. The master cylinder and the slave cylinder are hydraulically connected via a pressure line. The slave cylinder may be, for example, a slave cylinder with a cylindrical piston or else a so-called central release with a ring piston arranged concentrically with respect to a transmission input shaft. When the clutch pedal is depressed by the vehicle operator, i. Pressed with the foot, the pressure generated in the master cylinder is transmitted via the liquid column in the pressure line to the slave cylinder. As a result, the disengagement element of the clutch is acted upon by an actuating force via the slave cylinder piston in order to displace the clutch pressure plate via a disengagement mechanism and thus separate the engine from the transmission of the motor vehicle.

Motor vehicles of any kind are increasingly motorized, whereby the motor vehicle clutches must transmit ever higher torques. As a result, the motor vehicle clutches are dimensioned more and more, which is accompanied by a huge increase in the operating force to disengage the motor vehicle clutch. In a conventional hydraulic actuator, as described above, this leads to a high power demand on the clutch pedal, whereby the operating feeling of the clutch pedal for the vehicle driver is significantly adversely affected.

In the prior art solutions are known in which, for example, the master piston of the master cylinder always, for example US 4,918,921 , or optionally, for example US 5,002,166 , is kraftbeaufschlagbar and displaceable via a drivable by means of an electric motor gear. In principle, in such electrohydraulic actuation devices for clutches, three actuation modes can be realized, namely a first mode in which the clutch is actuated only via the pedal force without electrical assistance, a second mode in which the clutch is actuated only via the electric motor and a third mode in that the clutch operation is electrically assisted by the electric motor via the clutch pedal. However, the use of such a Hilfsaktuators, namely the electric motor, learns the driver of the vehicle on the clutch pedal but not the disengagement of the clutch re fl ective feedback.

Summary of the invention

It is an object of the invention to provide an electro-hydraulic intermediate cylinder for an actuator for actuating a motor vehicle clutch, which allows a motor vehicle driver, despite additional electrical Kupplungsaktuierung, a clutch pedal force optimized and precise to operate.

The object is achieved by an electro-hydraulic intermediate cylinder for an actuating device for actuating a motor vehicle clutch according to the features of the independent first claim. Further developments of the invention are specified in the dependent claims, the description and the accompanying drawings.

According to the invention, the intermediate cylinder is hydraulically connected via a first pressure line to a master cylinder and via a second pressure line to a slave cylinder.

The intermediate cylinder comprises according to the present invention, a cylinder housing, an electric motor, a threaded spindle, wherein the threaded spindle is drivingly connected to the electric motor, and a first piston and a second piston. The first piston and the second piston are arranged according to the invention within the cylinder housing and by the arrangement of the first piston and the second piston in the cylinder housing form a first hydraulic chamber first hydraulic volume and a second hydraulic chamber second hydraulic volume.

According to the present invention, the first piston and the second piston are arranged on the threaded spindle such that both the first piston and the second piston via the electric motor and the threaded spindle from a respective first position to a respective second position, or vice versa, are axially movable. According to the invention, the first piston is additionally hydraulically movable into the respective first position independently of the second piston, starting from the respective second position.

The term "axial" corresponds to a direction along or parallel to a longitudinal axis of the intermediate cylinder.

A decoupling of the motor vehicle clutch via a depression of the clutch pedal by the vehicle driver. This disengaging operation is optionally supported by the electric motor by moving the two pistons, namely the first piston and the second piston, from a respective first position to a respective second position via the threaded spindle. In order not to cause the depression of the clutch pedal with the foot for the driver of the vehicle by the electrical Hilfsaktuierung to force-intensive, i. To ensure a slight, power-optimized pressing of the clutch pedal, the first piston can be hydraulically moved from the respective second position to the respective first position. In this position combination, i. the second piston in the respective second position and the first piston in the respective first position, the clutch is disengaged.

By releasing the clutch pedal, the second piston is electrically movable to the respective first position and the clutch is closed, i. engaged.

The axial movement of the first piston from the respective second position into the respective first position is limited according to the invention by a first stop fixedly arranged on the threaded spindle. The first stop may also be integral with the threaded spindle, i. in one piece with this, be formed. Due to the formation of the first stop, the sum of the hydraulic volumes of the first hydraulic chamber and the second hydraulic chamber is constant regardless of the respective position of the first piston and the respective position of the second piston within the cylinder housing.

The inventive design of the electro-hydraulic intermediate cylinder allows a power-optimized and precise control of a disengaging operation of a motor vehicle clutch by the motor vehicle driver. In the disengaged position of the motor vehicle clutch, the motor vehicle driver experiences a feedback on the clutch pedal representative of this clutch state. The inventive design of the electro-hydraulic intermediate cylinder, the entire hydraulic volume is kept constant within the intermediate cylinder and so always provided exactly the necessary for the actuation of the motor vehicle clutch hydraulic volume.

In a preferred embodiment, the first piston in the respective first position via a first elastic element against a second stop, such as a fixedly mounted on the threaded spindle locking ring or a one-piece formed with the threaded spindle paragraph, biased. The first elastic element is preferably formed as a flat spring.

Generally, in the present context, the term "stop" is understood to mean any constructive action that allows axial movement up to the location of the respective stop, but not beyond.

Further preferably, the second piston is arranged axially displaceable on the threaded spindle and biased in the respective second position via a second elastic element in the direction of the respective first position. The second elastic element is preferably designed as a helical compression spring.

The first piston and the second piston are thus axially movable via the electric motor and the threaded spindle in cooperation with the first elastic element and / or the second elastic element, starting from a respective first position into a respective second position, or vice versa.

Due to the advantageous arrangement of the first elastic element, it is possible to support the electrical Hilfsaktuierungsvorgang and thus a smaller sized electric motor can be used, which in turn reflected in lower costs and a smaller space requirement. In an electric coupling process, namely engagement and / or disengagement of the motor vehicle clutch, the energy stored in the two elastic elements is displaced between the two elastic elements.

list of figures

• Fig. zeigt eine schematische Darstellung eines erfindungsgemäßen elektrohydraulischen Zwischenzylinders.

The invention will now be described by way of example with reference to the drawings.

• Fig. Shows a schematic representation of an electro-hydraulic intermediate cylinder according to the invention.

Detailed description of the invention

The illustrated in Fig. Electro-hydraulic intermediate cylinder 1 is via a first pressure line 2 with a master cylinder (not shown and via a second pressure line 3 with a slave cylinder (not shown) hydraulically connected. The cylinders are thus hydraulically connected in series, the electro-hydraulic intermediate cylinder 1 is arranged between the master cylinder and the slave cylinder.

The electrohydraulic intermediate cylinder 1 includes an electric motor 5 , a cylinder housing 4 with two pistons arranged therein, namely a first piston 7 and a second piston 8th , and a threaded spindle 6 ,

The threaded spindle 6 One end of the drive is effective with the electric motor 5 connected and other ends are on the threaded spindle 6 in turn, the first piston 7 and the second piston 8th arranged. The threaded spindle 6 serves for a rotary movement of the electric motor 5 in a linear movement of the two pistons 7 . 8th convert. The threaded spindle includes a nut 15 , Balls (not shown) and a screw 16 , The balls are between the snail 16 and the mother 15 arranged.

The two pistons 7 . 8th are on the threaded spindle 6 , inside the cylinder housing 4 , axially spaced from each other.

The term "axial" corresponds to a direction along or parallel to a longitudinal axis 17 of the electro-hydraulic intermediate cylinder 1 ,

The first position of the first piston 7 is about a second stop 14 namely a circlip, and a fixed first stop 11 axially on the threaded spindle 6 Are defined. The second stop 14 moves with the threaded spindle 6 and the first piston 7 is so between the second stop 14 and the first stop 11 axially displaceable, ie depending on the position of the threaded spindle 6 and thus the second stop 14 results in a variable axial movement of the first piston between the second stop 14 and the first stop 11 The second piston 8th is firmly on the threaded spindle 6 arranged. The arrangement of the first piston 7 and the second piston 8th in the cylinder housing 4 requires the formation of a first hydraulic chamber 9 first hydraulic volume and a second hydraulic chamber 10 second hydraulic volume. The first hydraulic chamber 9 is essentially through the cylinder housing 4 and the second piston 8th limited. The second hydraulic chamber is essentially through the cylinder housing 4 , the second piston 8th and the first piston 7 limited.

Between the cylinder housing 4 and the first piston 7 is a first elastic element 12 , more precisely a flat spring, arranged, which the first piston 7 in its first position against the second stop 14 pushes, ie towards the second piston 8th biased. Between the cylinder housing 4 and the second piston 8th is a second elastic element 13 , more precisely a helical compression spring arranged. The second elastic element 13 will be in the second position of the second piston 8th curious; excited.

The axial movement of the first piston 7 and the second piston 8th thus takes place via the electric motor 5 and the threaded spindle 6 in interaction with the first elastic element 12 and / or the second elastic element 13 ,

In the electrical actuation by the electric motor 5 of the electro-hydraulic intermediate cylinder 1 converts the threaded spindle 6 the rotary motion of the electric motor 5 into an axial movement - the threaded spindle 6 shifts axially - with respect to FIG. To the left, and there is a synchronous axial movement of the first piston 7 and the second piston 8th of the electro-hydraulic intermediate cylinder 1 with respect to Fig. to the left. In this case, the first hydraulic volume of the first hydraulic chamber decreases 9 and the second hydraulic volume of the second hydraulic chamber 10 remains unchanged for the time being. Further, during this axial movement with respect to FIG. 1, to the left, the first elastic member 12 relaxed and the second elastic element 13 curious; excited. By additionally pressing the clutch pedal by the vehicle driver, the first piston 7 , regardless of the second piston 8th , are hydraulically moved to its first position axially, with reference to FIG. Right, wherein this axial movement of the first piston 7 the first elastic element 12 is stretched again. This axial movement of the first piston 7 with respect to Fig. Right is by a first stop 11 limited. Thus, the sum of the hydraulic volumes of the first hydraulic chamber remains 9 and the second hydraulic chamber 10 constant.

A return movement of the second piston 8th from its second position in its first position and thus a return movement of the threaded spindle 6 can be actuated by the electric motor, this return movement through the second elastic element 13 , which is relaxed, supported. The return movement of the second piston from its second position to its first position always corresponds to a motor vehicle clutch state in which the motor vehicle clutch is engaged, ie the motor vehicle pedal is not pressed by the motor vehicle driver.

LIST OF REFERENCE NUMBERS

1

Electrohydraulic intermediate cylinder

2

First pressure line

3

Second pressure line

4

cylinder housing

5

electric motor

6

screw

7

First piston

8th

Second piston

9

First hydraulic chamber

10

Second hydraulic chamber

11

First stop

12

First elastic element

13

Second elastic element

14

Second stop

15

mother

16

slug

17

Longitudinal axis (of the electrohydraulic buffer)

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

• US 4918921 [0004]
• US 5002166 [0004]

Claims (5)

Electrohydraulic intermediate cylinder (1) for an actuating device for actuating a motor vehicle clutch, wherein the intermediate cylinder (1) is hydraulically connected via a first pressure line (2) to a master cylinder and via a second pressure line (3) to a slave cylinder a cylinder housing (4), an electric motor (5), - A threaded spindle (6), wherein the threaded spindle (6) with the electric motor (5) is drivingly connected, and - A first piston (7) and a second piston (8), wherein the first piston (7) and the second piston (8) within the cylinder housing (4) are arranged and by the arrangement of the first piston (7) and the second piston (8) in the cylinder housing (4) form a first hydraulic chamber (9) of first hydraulic volume and a second hydraulic chamber (10) second hydraulic volume, wherein the first piston (7) and the second piston (8) on the threaded spindle (6) are arranged so that both the first piston (7), as well as the second piston (8) via the electric motor (5) and the threaded spindle (6) from a respective first position to a respective second position, or vice versa, are axially movable and that the first piston (7) in addition, independently of the second piston (8), starting from the respective second position is hydraulically movable axially into the respective first position, wherein the movement of the first piston (7) of the jeweil igen second position in the respective first position by a fixed on the threaded spindle (6) first stop (11) is limited and so the sum of the hydraulic volumes of the first hydraulic chamber (9) and the second hydraulic chamber (10) regardless of the respective position of the first piston (7) and the respective position of the second piston (8) within the cylinder housing (4) is constant. Electrohydraulic intermediate cylinder (1) after Claim 1 , characterized in that the first piston (7) in the respective first position via a first elastic element (12) against a second stop (14) is biased. Electrohydraulic intermediate cylinder (1) after Claim 2 , characterized in that the first elastic element (12) is a flat spring. Electrohydraulic intermediate cylinder (1) after Claim 1 . 2 or 3 , characterized in that the second piston (8) is arranged axially displaceable on the threaded spindle (6) and in the respective second position via a second elastic element (13) is biased. Electrohydraulic intermediate cylinder (1) after Claim 4 , characterized in that the second elastic element (13) is a helical compression spring.

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