WO2017129180A1

WO2017129180A1 - Actuator for an actuation device, comprising a storage chamber with a variable volume, and an actuation device comprising a corresponding actuator

Info

Publication number: WO2017129180A1
Application number: PCT/DE2017/100050
Authority: WO
Inventors: Jerome Malitourne; Alan Barrera
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2016-01-28
Filing date: 2017-01-26
Publication date: 2017-08-03
Also published as: DE102016201296B3

Abstract

The invention relates to an actuator for an actuation device of a friction clutch, having a housing in which at least one piston is arranged in an axially movable manner along an adjustment path in order to convey hydraulic fluid out of a pressure chamber of the housing to a slave cylinder. The actuator has a storage chamber with a variable volume for the hydraulic fluid, the variable maximum storage volume of said storage chamber corresponding constantly to a hydraulic fluid volume displaced out of the pressure chamber by the at least one piston. The invention additionally relates to an actuation system comprising a corresponding actuator.

Description

Actuator for an actuator

with a variable volume storage chamber and an actuator with a corresponding actuator

The present invention relates to an actuator for an actuator of a friction clutch and an actuator with a corresponding actuator. Such friction clutches serve in particular to interrupt a torque flow from a drive motor to a drive train of a motor vehicle.

To actuate friction clutches actuators are known to a master cylinder and a slave cylinder, which are connected to each other via a hydraulic path. In motor vehicles with manual transmission, the master cylinder is actuated by means of a clutch pedal by a driver of the motor vehicle. As a result, a hydraulic fluid is displaced from the master cylinder via the hydraulic path to the slave cylinder, which disengages and / or engages the friction clutch. For example, the slave cylinder may be a CSC. To reduce CO 2 emissions from motor vehicles with manual transmissions, actuators for the friction clutch are known, which have an additional actuator. This enables a so-called "sailing function", by means of which the drive motor of the motor vehicle can be switched off by opening the clutch during coasting, whereby the slave cylinder is connected to the master cylinder and the actuator so that both the master cylinder and the actuator control the slave cylinder and Preferably, the master cylinder and the actuator are arranged in series, so that a transfer between the actuator and the master cylinder and vice versa is possible. For example, in the prior art, actively controlled valves or a floating piston of the actuator are known, but such actively controlled valves require a high degree of control effort, and a smooth and uncomplicated transfer from the actuator to the driver in known actuators with floating Piston not readily possible because in these the clutch pedal is rigid when the actuator operates the friction clutch.

The object of the invention is therefore to solve the problems described with reference to the prior art at least partially and in particular to provide an actuator for an actuator of a friction clutch, with a smooth and easy transfer from the actuator to the driver of a motor vehicle is possible. In addition, an actuating system with a corresponding actuator is to be specified, which allows a smooth and uncomplicated transfer from the actuator to the driver of the motor vehicle.

These objects are achieved with an actuator and an actuating system according to the features of the independent claims. Further advantageous embodiments of the invention are specified in the dependent formulated claims. It should be noted that the features listed individually in the dependent claims can be combined in any technologically meaningful manner and define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

The actuator according to the invention for an actuating device of a friction clutch has a housing in which at least one piston is arranged axially movable along a travel in order to convey a hydraulic fluid from a pressure chamber of the housing to a slave cylinder, wherein the actuator has a volume-variable storage chamber for the hydraulic fluid whose variable maximum storage volume always corresponds to a displaced by the at least one piston from the pressure chamber volume of the hydraulic fluid.

The actuator proposed here can be used in particular in connection with an actuating device of a friction clutch, such as a single-disc dry clutch. Such an actuating device regularly has a master cylinder and a slave cylinder. For vehicles with manual The actuator is used in particular to implement a so-called "sailing function" in which the drive motor of the motor vehicle can be switched off by automatically opening the friction clutch during coasting of the motor vehicle in order to reduce CO 2 emissions of the motor vehicle As a result, the friction clutch can be actuated by the driver alone, by the actuator alone or jointly by the driver and the actuator.

The actuator has a housing in which at least one piston is arranged to be axially movable along a travel. For this purpose, the piston can be arranged on a spindle which can be driven rotationally by means of a motor. With this, the piston is drivable in an axial direction of the actuator or the piston. By means of the at least one piston, a hydraulic fluid from a pressure chamber of the housing to a slave cylinder is displaceable. For this purpose, the pressure chamber in particular has a connection for a hydraulic route to the slave cylinder. By means of the at least one piston is a hydraulic fluid, such as hydraulic oil, displaced from the pressure chamber. The actuator further has a volume-variable storage chamber for the hydraulic fluid. A volume-variable storage chamber is, in particular, a storage chamber whose volume can be changed by flowing in a hydraulic fluid. For this purpose, the storage chamber may have at least one elastic and / or adjustable wall, which is adjustable by a pressure of the hydraulic fluid up to a maximum storage volume of the storage chamber. In the actuator proposed here, this maximum storage volume is variable such that it always corresponds to a volume of the hydraulic fluid displaced by the at least one piston from the pressure chamber. This means in other words that the maximum deflectability of the at least one elastic or adjustable wall is variable so that always the amount of hydraulic fluid can flow into the maximum storage chamber, which is displaced by the at least one piston from the pressure chamber. This also means that the maximum storage volume of the storage chamber (substantially) corresponds to the actuated actuator volume. If, for example, the actuator is actuated by 50%, (essentially) exactly 50% of the set by the at least one piston displaced in the pressure chamber volume as the maximum storage volume of the storage chamber, so that in an actuator in any case a volume of more than 100% of possible hydraulic fluid in the storage chamber, the slave cylinder or master cylinder can occur. The volume-variable storage chamber advantageously allows a transfer from the actuator to the driver without actively controllable valves between the master cylinder and the storage chamber and between the master cylinder and the slave cylinder.

In addition, it is advantageous if the maximum storage volume of the storage chamber is variable in proportion to the travel of the at least one piston. For this purpose, the flexible and / or adjustable wall of the storage chamber, for example, attached to the at least one piston and / or be movable with the at least one piston.

It is also advantageous if the storage chamber has at least one wall which is movable with the piston and by means of which the maximum storage volume can be changed.

Moreover, it is advantageous if movement of the wall is blocked when the maximum storage volume through the housing is reached. For this purpose, the housing may for example have a shoulder, which may be formed as a change in an inner diameter of the housing. The wall abuts when reaching the maximum storage volume against the paragraph and is thereby blocked.

Preferably, the wall is biased by a first spring.

It is also advantageous if the actuator has a spindle rotatable by a motor, with which the at least one piston is axially movable.

According to a further aspect of the invention, an actuating device for a friction clutch is proposed, which has a slave cylinder, a master cylinder and an actuator according to the invention, wherein the slave cylinder by the Master cylinder and the actuator is actuated. The master cylinder is preferably connected to a first hydraulic line to the actuator and the actuator preferably connected to a second hydraulic line to the slave cylinder. For this purpose, the actuator in particular has a first connection, through which hydraulic fluid can flow from the master cylinder into a volume-variable storage chamber of the actuator and / or a pressure chamber of the actuator and / or can flow out. Furthermore, the pressure chamber of the actuator in particular has a second connection, through which hydraulic fluid can flow to the slave cylinder and / or from the slave cylinder back to the pressure chamber. The master cylinder can be actuated in particular with a clutch pedal by a driver of a motor vehicle. In contrast, the actuator is preferably operated electrically by means of an electric motor. The slave cylinder is operable to engage and / or disengage the friction clutch by the actuator alone, by the master cylinder alone or together by the master cylinder and the actuator. For further details, reference is made to the description of the actuator according to the invention.

In addition, it is advantageous if a passive pressure valve or a floating piston of the actuator is arranged in a hydraulic line between the master cylinder and slave cylinder. The passive pressure valve can be realized in particular inexpensively in the form of a groove seal, for example in the region of a primary seal of the pressure chamber. Alternatively, at least one piston of the actuator may be formed as a floating piston. In this case, the at least one piston comprises a piston receiver, which can be driven by a spindle of the actuator and a floating piston.

According to an advantageous embodiment, a storage chamber of the actuator has a storage chamber characteristic which runs below a limit pressure which is less than or equal to the pressure when the clutch is fully disengaged. Particularly preferably, the limit pressure is equal to the lowest pressure at fully disengaged clutch. This ensures that a displaced from the master cylinder volume of the hydraulic fluid is clearly shifted to the storage chamber or the slave cylinder. This decision is pressure-dependent, that is without actively controlled valve instead. It is also advantageous if a storage chamber of the actuator is a storage cherkammerkennlinie extending along a range of at least 75% of a travel of a piston of the actuator substantially below, in particular below, a clutch characteristic. The storage chamber characteristic curve describes the pressure in the storage chamber as a function of the volume of hydraulic fluid present in the storage chamber. The clutch characteristic describes the pressure of the hydraulic fluid in the slave cylinder as a function of the volume of the hydraulic fluid in the slave cylinder. It is also preferred that the storage chamber characteristic curve runs along the entire travel of the piston of the actuator below the clutch characteristic.

Advantageously, an inflow of the hydraulic fluid into a storage chamber of the actuator or an outflow of the hydraulic fluid from the storage chamber without actively controlled valve or valveless controllable.

The invention and the technical environment will be explained in more detail with reference to FIGS. It should be noted that the figures show a particularly preferred variant of the invention, but this is not limited thereto. The same components are provided in the figures with the same reference numerals. They show by way of example and schematically:

1 shows a first schematic representation of an actuating system; 2 shows a second schematic representation of the actuation system;

3 shows a schematic representation of a purely actuatoric actuation of a

friction clutch;

4 shows a first schematic illustration of an actuation of the friction clutch by a driver and an actuator;

5 is a second schematic representation of the operation of the friction clutch by the driver and the actuator. 6 shows a schematic illustration of the actuation of the friction clutch when the control is transferred to the driver starting from the state of FIG. 5;

Fig. 7: schematic representation of the unactuated friction clutch;

8 shows a perspective sectional view of the actuator;

9-12: a representation of the manual operation of the friction clutch with Betriebszustands- and storage chamber pressure representation;

13-15: a representation of a purely actuator actuation of the friction clutch with

Operating condition and storage chamber pressure representation;

Fig. 16-20: a representation of a combined operation of the friction clutch by the driver and the actuator with Betriebszustands- and storage chamber pressure representation;

FIGS. 21-26 are an illustration of a manual operation by a driver on an actuator return with operating condition and accumulator pressure maps; and

Fig. 27: a storage chamber characteristic and clutch characteristic.

1 shows a first schematic representation of an actuating system 2 with a master cylinder 14 and a slave cylinder 8 for a friction clutch 3, which are connected to one another via an actuator 1. As a result, the master cylinder 14, which can be actuated by a clutch pedal 22, is connected to the actuator 1 via a hydraulic path 15, which is designed here in the manner of a first hydraulic line 20. The actuator 1 is in turn connected via a second hydraulic line 21 to the slave cylinder 8. 2 shows a second schematic representation of the actuating system 2 with the master cylinder 14, the actuator 1 and the slave cylinder 8. In the actuator 1, a piston 5 is arranged axially movable along a travel path 3. Furthermore, the actuator 1 has a pressure chamber 7 and a volume-variable storage chamber 9 with a wall 10 which is biased by a first spring 1 1. The piston 5 can be driven by means of a motor 12. The master cylinder 14 is connected to the volume-variable storage chamber 9 and the slave cylinder 8 via the first hydraulic line 20, so that by means of a master cylinder piston 23 of the master cylinder 14, a hydraulic fluid from the master cylinder 14 in the volume variable storage chamber 9 and / or the slave cylinder 8 is displaceable. The master piston 23 can be actuated by the clutch pedal 22 by a driver of a motor vehicle. In the first hydraulic line 20 is located between the master cylinder 14 and the slave cylinder 8, a seal which may be formed as a passive pressure valve 16 or (not shown here) as a floating piston. The pressure chamber 7 of the actuator 1 is also connected via the second hydraulic line 21 to the slave cylinder 8. Thus, a slave piston 24 of the slave cylinder 8 can be actuated both by the master cylinder 14 and the actuator 1. The slave piston 24 in turn actuates the friction clutch third

FIGS. 3-7 show hydraulic diagrams for different operating situations of the actuating system 2. FIG. 3 shows the actuating system 2 in an operating situation in which the piston 5 of the actuator 1 is actuated by 60%. This means that the piston 5 was moved by the motor 12 into the pressure chamber 7 and there displaces 60% of the volume of the pressure chamber 7. As a result, 60% of a hydraulic fluid in the pressure chamber 7 are moved via the second hydraulic line 21 into the slave cylinder 8. At the same time, the piston 5 enlarges a maximum storage volume of the storage chamber 9 to 60%, so that the maximum storage volume corresponds to the volume displaced by the piston in the pressure chamber. Since a wall 10 of the pressure chamber 9 is biased by the first spring 1 1, the storage chamber 9 is empty in the operating situation shown in FIG. 3. FIG. 4 shows the actuation system 2 of FIG. 3 in an operating situation after a driver has also actuated the master piston 23 of the master cylinder 14 by means of the clutch pedal 22 by 60%. Since a storage chamber characteristic curve 18 extends below a clutch characteristic line 19 (cf. FIG. 27), the hydraulic fluid flows from the master cylinder 14 via the first hydraulic line 20 into the storage chamber 9. In this way, the wall 10 of the storage chamber 9 is adjusted against the bias of the first spring 11 until the maximum storage volume of 60% of the storage chamber 9 is reached, which is specified here by the piston 5 of the actuator 1.

FIG. 5 shows the actuating system 2 of FIG. 4 in an operating situation in which the master piston 23 of the master cylinder 14 has been 100% actuated by the driver by means of the clutch pedal 22. Since the maximum storage volume of the storage chamber 9 has already been exhausted, the seal executed here as a passive pressure valve 16 opens so that the remaining 40% hydraulic fluid of the master cylinder 14 flows via the first hydraulic line 20 into the slave cylinder 8, so that the slave piston 24 is adjusted to 100% ,

FIG. 6 shows the actuating system 2 of FIG. 5 in an operating situation after the piston 5 of the actuator 1 has been completely retracted. The hydraulic fluid previously located in the storage chamber 9 has thereby flowed through the gasket designed as a passive pressure valve 16 into the pressure chamber 7, which is now 100% open. Since the master cylinder 14 is still operated to 100%, and the slave cylinder 8 is operated to 100%.

FIG. 7 shows the actuating system 2 of FIG. 6 in an operating situation after the master piston 23 of the master cylinder 14 has been completely released via the clutch pedal 22 by a driver. The hydraulic fluid previously located in the slave cylinder 8 has thereby flowed via the second hydraulic line 21 into the pressure chamber 7 of the actuator 1. The hydraulic fluid previously located in the pressure chamber 7 of the actuator 1 has thereby flowed into the master cylinder 14 via a third hydraulic line 31 and the first hydraulic line 20. The third hydrau- likleitung 31 is only open when the piston 5 of the actuator 1 is completely moved out of the pressure chamber 7.

Fig. 8 shows the actuator 1 in a perspective sectional view. The actuator 1 has a housing 4, in which the piston 5 is arranged axially movable. In the variant of the actuator 1 shown here, the piston 5 comprises a piston receiver 28. The piston receiver 28 is arranged on a spindle 13, via which the piston receiver 28 can be moved axially on the spindle 13. For this purpose, the spindle 13 by a (electric) motor 12 is rotatably driven. By means of the Kolbennehmers 28, the piston 5 is retractable into the pressure chamber 7 of the housing 7. The housing 4 further has a first connection 25, via which the actuator 1 can be connected to the master cylinder 14, not shown here. In addition, the actuator 1 in the region of the pressure chamber 7 has a second connection 26, via which the actuator 1 can be connected to the slave cylinder 8, not shown here. The piston 5 is also biased by a second spring 27 against the piston receiver 28.

Various operating states of the actuating system 2 are shown in FIGS. 9-26. In addition to a sectional view of the actuator 1, the figures show the respective operating point in normal or special operation and the associated clutch characteristic curve 19 with the respective operating point. In Figs. 9-12, an operation is exclusively by the driver. In this case, hydraulic fluid can flow via the first port 25, the pressure chamber 7 and the second port 26 to the slave cylinder 8, not shown here. The hydraulic fluid can also flow back from the slave cylinder 8 to the master cylinder 14 (not shown here) via the same flow path. The flow of the hydraulic fluid is shown in Figs. 9-12 by an arrow.

Various operating situations of the actuating system 2 are shown in FIGS. 13-15, in which the actuation is effected solely by the actuator 1. This is the case, for example, with the so-called "sailing function." Sailing here means an operating mode of the motor vehicle in which the motor vehicle rolls and the clutch is open, ie there is no connection between the drive motor and the drive train of the motor vehicle. 14 shows the piston 5 after this was completely moved by the piston 28 in the pressure chamber 7. As a result, a storage chamber 9 has been opened completely, which extends in an axial direction annularly from a shoulder 29 of the housing 4 to the wall 10, which has been adjusted with the piston holder 28 extends.

FIGS. 16-20 show a combined actuation by the actuator 1 and the driver via the master cylinder 14 (not shown here) in different operating situations. After the actuator 1 has been fully actuated in FIG. 17, the storage chamber 9 is formed between the shoulder 29 and the wall 10. If, as shown in FIG. 18, the master cylinder 14, not shown here, is also fully actuated by a driver, the hydraulic fluid flows through the first port 25 into the storage chamber 9 until the wall 10 reaches the storage chamber 9 when it reaches the maximum storage volume 29 is blocked. After releasing the clutch pedal 22, the hydraulic fluid is conveyed from the storage chamber 9 through the wall 10 through the first port 25 back to the donor cylinder 14, not shown here. For this purpose, the wall 10 is biased by means of the first spring 1 1 (FIG. 19).

Figs. 21-26 show an operation by the driver on the actuator return path.

FIG. 27 shows the course of the storage chamber characteristic 18 and the clutch characteristic curve 19. The storage chamber characteristic 18 extends in a region 30 of at least 75% of the travel 6, not shown here, of the piston 5 of the actuator 1 below the clutch characteristic curve 19. Here, the region 30 lies in particular at the high pressures and volumes. Furthermore, FIG. 27 also shows that the clutch characteristic curve 19 has a lowest pressure 32 when the clutch is fully disengaged, which corresponds to a limit pressure 33. The storage chamber 9 is designed so that the storage chamber characteristic 18 is completely below the limit pressure 33. This ensures that a displaced from the master cylinder 14 volume of the hydraulic fluid is clearly shifted to the storage chamber 9 or the slave cylinder 8. This happens depending on the pressure, ie without actively controlled valve. The present invention enables a smooth and uncomplicated transfer from the actuator 1 to the driver of a motor vehicle while the actuation system 2 of the friction clutch 3 performs a "sailing function".

LIST OF REFERENCES

actuator

actuating system

friction clutch

casing

piston

Travel Range

pressure chamber

slave cylinder

storage chamber

wall

first spring

engine

spindle

Master cylinder

hydraulic track

passive pressure valve

Storage chamber characteristic

Clutch characteristic

first hydraulic line

second hydraulic line

clutch pedal

master piston

slave piston

first connection

second connection

second spring

piston takers

paragraph

Area third hydraulic line

Pressure at fully disengaged clutch limit pressure

Claims

claims

Actuator (1) for an actuating device (2) of a friction clutch (3), comprising a housing (4) in which at least one piston (5) is arranged to be axially movable along a travel path (6) in order to move a hydraulic fluid out of a pressure chamber (7 ) of the housing (4) to promote a slave cylinder (8), wherein the actuator (1) has a volume variable storage chamber (9) for the hydraulic fluid whose variable maximum storage volume always through the at least one piston (5) from the pressure chamber ( 7) corresponds to displaced volume of the hydraulic fluid.

Actuator (1) according to claim 1, wherein the maximum storage volume of the storage chamber (9) is proportional to the travel (6) of the at least one piston (5) variable.

Actuator (1) according to one of the preceding claims, wherein the storage chamber (9) has at least one wall (10) which is movable with the at least one piston (5) and by which the maximum storage volume is variable.

Actuator (1) according to claim 3, wherein a movement of the wall (10) upon reaching the maximum storage volume through the housing (4) is blocked.

Actuator (1) according to claim 3 or 4, wherein the wall (10) is biased by a first spring (1 1).

Actuator (1) according to one of the preceding claims, comprising a by a motor (12) rotatable spindle (13), with which the at least one piston (5) is axially movable.

7. actuating device (2) for a friction clutch (3), comprising a slave cylinder (8), a master cylinder (14) and an actuator (1) according to one of preceding claims, wherein the slave cylinder (8) by the master cylinder (14) and the actuator (1) is actuated.

8. Actuating device (2) according to claim 7, wherein in a hydraulic path (15) between the master cylinder (14) and slave cylinder (8) a passive pressure valve (16) or a floating piston of the actuator (1) is arranged.

9. Actuator (2) according to claim 7 or 8, wherein a storage chamber (9) of the actuator (1) has a storage chamber characteristic (18) which extends below a limit pressure (33) which is less than or equal to the pressure at fully disengaged clutch ,

10. Actuating device (2) according to one of claims 7 to 9, wherein an inflow of the hydraulic fluid into a storage chamber (9) of the actuator (1) o- an outflow of the hydraulic fluid from the storage chamber (9) without actively controlled valve or valveless controllable is.