WO2014044269A2

WO2014044269A2 - Target device for inductive displacement measurement of a master piston

Info

Publication number: WO2014044269A2
Application number: PCT/DE2013/200142
Authority: WO
Inventors: Jochen Blauhut
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2012-09-19
Filing date: 2013-08-28
Publication date: 2014-03-27
Also published as: CN104619998B; DE102013217115A1; DE112013004550A5; CN104619998A; IN2015DN01453A; WO2014044269A3

Abstract

The invention relates to a target device for inductive displacement measurement of a master piston, wherein the target device is formed as a sleeve with a slit and is produced from a metal material, and is designed for being fixed under stress on a piston body. With the target device proposed here, a master cylinder system can be constructed in a very short form and at the same time mass production can be achieved without involving additional adjustment.

Description

Target device for an inductive displacement measurement of a master piston

The invention relates to a target device for an inductive displacement measurement of a master piston, as well as a master piston and a hydraulic master cylinder.

In the prior art, massive aluminum targets are used, which allow the inductive displacement measurement of the master cylinder. Disadvantage of such aluminum targets is that they are particularly space-consuming axially, because such aluminum targets can be arranged only above the primary pressure chamber of a master cylinder. A master cylinder with a secondary and primary pressure chamber has different diameters in these two pressure chambers. The aluminum target is used to seal a gap and therefore can only be moved in the smaller diameter secondary pressure space. With such an arrangement, the master cylinder becomes very long. In addition, one needs a suitable attachment to create the smallest possible gap between the aluminum target and the inner wall of the secondary pressure chamber. For tolerance compensation squish ribs are provided in the prior art, which are pressed. Overall, this requires more aluminum material than is necessary for a suitable signal strength or signal quality of a displacement measurement. Even with squish ribs optimal centering of the aluminum target is not possible.

On this basis, the present invention has the object, at least partially overcome the known from the prior art disadvantages. The object is solved by the features of the independent claims. Advantageous developments are the subject of the dependent claims.

The invention relates to a target device for an inductive displacement measurement of a master piston, wherein the target device is formed sleeve-shaped with a slot and made of a metallic material and is adapted to be fixed under tension on a piston body.

The target device is a body with a defined axial length, via which it is possible to inductively measure the position of a master piston. For this purpose, the target device is at least axially fixed to the master piston. The target device proposed here is sleeve-shaped and formed with a slot. Such a sleeve-shaped target device can over a master piston are pushed, and are fixed by spreading under tension on the master piston. Advantageously, the target device is made of a metallic material, in particular aluminum. Such a target device can be made very thin, and does not have to perform any additional functions, such as mechanical stability or the creation of a small air gap between the master piston and the cylinder. At the same time, the target device can just be made so thin that a sufficient signal strength or signal quality is achieved. In addition, it must be designed solely for the exercise of its clamping force.

According to a further advantageous embodiment of the target device, the target device has a recess for axial positioning on a piston body, and preferably the recess is arranged on both sides of the slot.

Such a recess corresponds to a survey on the master piston, so that the target device can be easily mounted, namely by simply pushing the target device up to a locking of the recess on the survey of the master piston. In order to keep the mechanical load on the target device when sliding as low as possible, the recess is preferably arranged on both sides of the slot, so that the survey during the sliding on the master piston only extends the slot and not in the radial direction, a force on the sleeve-shaped target device exercise and possibly deformed. The provision of such a recess, or together with a survey on the master piston, allows a very accurate reliable arrangement of the target device on the master piston, so that a large-scale production and even mass production is possible in which the respective mounted target device are not adjusted in the Wegmesssensorik got to. Rather, a standard adjustment can be used because the axial position of the target device can be made sufficiently accurate by the interaction of the recess and survey by simply pushing.

In a further advantageous embodiment, the target device has a first end and a second end, wherein the first end is adapted to form a stop for a dynamic Axialdichtring.

As already described above, the master piston has two dynamic axial sealing rings, which allow an axial sealing of the moving master piston. Preferably, an axial sealing ring is permanently arranged in the primary pressure chamber and a second axial sealing ring is free in one state in the primary pressure chamber and in another state it rests in the secondary pressure chamber. For axially securing the position of at least one Axialdichtrings the target device can be used. In this case, the first end, on which the dynamic axial sealing ring can rest, preferably has a corresponding surface design, and particularly preferably it is embossed. Thus, the sensitive axial seal is not damaged.

According to a further advantageous embodiment, the target device is made of a sheet metal material.

While the previously known target devices had to be made of solid material, it is possible with the sleeve-shaped target device to produce these from favorable sheet material, preferably to punch. But there are also other manufacturing methods possible, which are suitable to cut out a defined shape of a sheet material. However, it is advantageous when punching that machining of the edges of the target device takes place at the same time. For example, at least one end of the target device may be embossed.

According to a further aspect of the invention, a master piston for a hydraulic master cylinder is proposed which has at least one piston body, a target device, a first dynamic axial sealing ring and a second dynamic axial sealing ring.

Such a master piston for a hydraulic master cylinder, as proposed here, can be made very short and at the same time allow a very accurate displacement measurement with simple adjustment. For this purpose, a piston body is provided, which takes over the mechanical functions of the master piston. To move the master piston two dynamic Axialdichtringe are provided which seal an intermediate gap between the piston body and the master cylinder, and in particular a primary pressure chamber of a secondary pressure chamber of the master cylinder axially separate from each other. Depending on the position of the master piston seals the first dynamic axial seal or the second dynamic axial seal. Both the first dynamic axial sealing ring and the second dynamic axial sealing ring can be designed as axial sealing rings, which can be positioned axially via the target device.

According to a further aspect of the invention, a hydraulic master cylinder for a hydraulically actuated clutch is proposed which comprises a master piston according to the above Description, a pressure cylinder having a primary pressure chamber and an induction coil for detecting the position of the master piston.

The hydraulic master cylinder is configured, for example, to hydraulically actuate a clutch. For this purpose, a slave cylinder is hydraulically engaged or disengaged via the master cylinder. In the hydraulic master cylinder, a pressure cylinder surrounds the master piston according to the above description. Such a pressure cylinder has a primary pressure chamber and a secondary pressure chamber, wherein the target device can be arranged in the primary pressure chamber. To determine the position of the master piston in the pressure cylinder, an induction coil is provided, which is preferably arranged outside of the printing cylinder. Thus, the target device moves in the induction field of the induction coil. Such a hydraulic master cylinder can be made very short and at the same time provides a very accurate measurement of the position of the master piston.

According to a further advantageous embodiment of the hydraulic master cylinder, the target device is arranged in the primary pressure chamber and spaced from the inner wall of the primary pressure chamber.

Because the target device is not intended to be sealed, and the primary pressure chamber is radially expanded from the secondary pressure chamber of the pressure cylinder, unlike the prior art target device, the target device can also be located in the primary pressure chamber. A seal to the inner wall of the primary pressure chamber by the target device is not necessary in this configuration. Rather, the target device may be adapted in its radial extension to the dimension of the secondary pressure chamber, that is, be significantly smaller than the diameter of the inner wall of the primary pressure chamber. At the same time, the very thin target device can be arranged around a mechanically or structurally required diameter of the piston body around, and does not have to be added axially.

According to a further aspect of the invention, a motor vehicle is proposed which has a drive unit with an output shaft, a drive train and a clutch for releasably connecting the output shaft to the drive train, wherein the clutch comprises a hydraulic master cylinder as described herein.

In a motor vehicle, the given installation space for a clutch arrangement is very small. In fact, in the past, the space has not increased and at the same time to transmitted power significantly increased. Therefore, larger engagement forces and disengagement forces also have to be generated, which requires more powerful master cylinders. By using a master cylinder according to the above description, a smaller master cylinder of the same power or an equally large master cylinder can be used with greater power.

According to a further advantageous embodiment of the motor vehicle, the drive unit is arranged in the motor vehicle in front of a driver's cab and transversely to a longitudinal axis of the motor vehicle.

Most motor vehicles today have a front-wheel drive and therefore preferably arrange the drive unit, for example an internal combustion engine or an electric motor, in front of the driver's cab and transversely to the main drive direction. The space is particularly low especially with such an arrangement and it is therefore particularly advantageous to use a small size coupling.

The installation space situation for passenger cars of the small car class according to European classification is exacerbated. The units used in a passenger car of the small car class are not significantly reduced compared to passenger cars larger car classes. Nevertheless, the available space for small cars is much smaller. At the same time, significantly more small cars are produced than all other car categories. The master cylinder described above is particularly suitable for use in clutches of small size, because in addition to the reduced size also simplified mass production with little adjustment effort is possible. Passenger cars are classified according to vehicle class according to, for example, size, price, weight, power, but this definition is subject to constant change according to the needs of the market. In the US market, cars of the class small cars and microcars are classified by European classification of the class of subcompact car and in the British market they correspond to the class Supermini, for example, the class City Car. Examples of the micro car class are a Volkswagen Fox or a Renault Twingo. Examples of the small car class are an Alfa Romeo Mito, Volkswagen Polo, Ford Fiesta or Renault Clio.

The features listed individually in the claims can be combined with one another in any technologically meaningful manner and can be supplemented by explanatory facts from the description and details from the figures, wherein further embodiments of the invention are shown. The invention and the technical environment will be explained in more detail with reference to FIGS. The figures show particularly preferred embodiments, to which the invention is not limited. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. Show it:

1 shows a target device in a master cylinder in section;

2 shows a target device with a recess; and

Fig. 3: a motor vehicle with coupling.

In Fig. 1, a target device 1 is shown, which is applied to a piston body 4. The piston body 4 is located in a master cylinder 10 with an inner wall 16. The master cylinder 10 has a primary pressure chamber 13 and a secondary pressure chamber 14. The piston body 4 is driven by an actuator 24. For sealing a first Axialdichtring 9 and a second Axialdichtring 1 1 are provided, wherein the first Axialdichtring seals 9 in the primary pressure chamber and the second Axialdichtring 1 1 seals in the secondary pressure chamber in a shifted to the right after the figure state. The target device 1 is set up so that it can also be inserted into the secondary pressure chamber 14. The target device 1 has a first end 6 and a second end 7, in which case the first end 6 forms a stop 8 for the first axial sealing ring 9. The position of the piston body 4 or the target device is registered via an induction coil 15.

In Fig. 2, a target device 1 is shown, which is applied to a piston body 4. Here, the slot 3 of the target device 1 can be seen in this view, which is provided with a double-sided recess 5, so that the target device 1 is axially positioned over a survey 25 of the piston body 4.

In Fig. 3, a motor vehicle 17 is shown, which has a drive unit 18, which is shown here as an internal combustion engine. The drive unit 18 is connected via its output shaft 19 by means of a clutch 12 with a drive train 20 shown purely schematically. In this motor vehicle 17, the drive unit 18 is located with its motor axis 23 transversely to the longitudinal axis 22 of the motor vehicle 17 and in front of a driver's cab 21. With the target device proposed here, a very short design of a master cylinder system can be performed and at the same time a mass production can be achieved without additional adjustment effort.

Reference character list Target device

master piston

slot

piston body

recess

first end

second end

attack

first axial sealing ring

Master cylinder

second axial sealing ring

clutch

primary pressure chamber

secondary pressure chamber

induction coil

inner wall

motor vehicle

drive unit

output shaft

powertrain

cab

longitudinal axis

motor axis

actuator

survey

Claims

claims

1 . Target device (1) for an inductive displacement measurement of a master piston (2), wherein the target device (1) is sleeve-shaped with a slot (3) and made of a metallic material, and is arranged to be fixed under tension on a piston body (4) to become.

2. Target device (1) according to claim 1, wherein the target device (1) has a recess (5) for axial positioning on a piston body (4), and preferably the recess (5) on both sides of the slot (3) is arranged.

3. Target device (1) according to claim 1 or 2, wherein the target device (1) has a first end (6) and a second end (7), wherein the first end (6) is adapted to a stop (8) for to form a dynamic axial sealing ring (9).

4. Target device (1) according to any one of the preceding claims, wherein the target device (1) is punched from a sheet material.

5. master piston (2) for a hydraulic master cylinder (10), comprising at least one piston body (4), a target device (1) according to any one of the preceding claims, a first dynamic Axialdichtring (9) and a second dynamic Axialdichtring (1 1).

6. master piston (2) according to claim 5, wherein the first dynamic axial sealing ring (9) by means of the target device (1) is axially securable.

7. Hydraulic master cylinder (10) for a hydraulically actuated clutch (12), comprising a master piston (2) according to claim 5 or 6, a pressure cylinder (13) having a primary pressure chamber (14), an induction coil (15) for determining the position of the master piston (2).

The hydraulic master cylinder (10) of claim 7, wherein the target device (1) is disposed in the primary pressure chamber (14) and spaced from the inner wall (16) of the primary pressure chamber (14).

9. motor vehicle (17) comprising an Antriesbseinheit (18) with an output shaft (19), a drive train (20) and a coupling (12) for releasably connecting the output shaft (19) to the drive train (20), wherein the clutch (12 ) comprises a hydraulic master cylinder (10) according to claim 7 or 8.

10. motor vehicle (17) according to claim 9, wherein the drive unit (18) in the motor vehicle (17) in front of a driver's cab (21) and transverse to a longitudinal axis (22) of the motor vehicle (17) is arranged.