DE102014201792A1 - Actuator device for a hydraulic brake of a vehicle, vehicle and method for actuating a hydraulic brake of a vehicle - Google Patents

Abstract

The invention relates to an actuator device for a hydraulic brake device of a vehicle, in particular a two-wheeler such as an electrically operable bicycle, comprising a hydraulic brake cylinder having a first cylinder chamber and a second cylinder chamber fluidly separated from the first cylinder chamber, each filled with hydraulic fluid are a piston device disposed in the brake cylinder between the first cylinder chamber and the second cylinder chamber and configured to apply pressure to the hydraulic fluid in the second cylinder chamber upon pressurization of the hydraulic fluid in the first cylinder chamber, a controller, and a dielectric Elastomeraktor, which is acted upon by the control device with an electric field, and which is extensible and / or compressible in response to the applied electric field, wherein the dielectric elastomer actuator is adapted to reduce the pressure on the hydraulic fluid in the second cylinder chamber when subjected to an electric field.

Description

The invention relates to an actuator device for a hydraulic brake of a vehicle, a vehicle, in particular a two-wheeler, with a hydraulic brake and a method for actuating a hydraulic brake of a vehicle, in particular a two-wheeler.

While the invention may be applied to vehicles of various types, particularly relatively light and inexpensive vehicles such as single-lane, relatively slow-moving high center-of-gravity vehicles, the invention will be further described by the example of a two-wheeled bicycle or pedelec. The bicycle can hereby be designed as a bicycle with a motor drive, in particular an electric drive, which can act instead of or in addition to the muscle power of the driver.

State of the art

Two-wheelers are in principle provided with brakes, which are adapted to the characteristics of the respective vehicle. For example, brakes for light, generally slow-moving vehicles such as bicycles, pedelecs or mopeds may be designed differently than brakes for heavy, fast-moving motorcycles. For light single-track two-wheeler hydraulic bicycle brakes are known, which are designed as disc or rim brakes. In general, the front wheel and the rear wheel have independent pressure lines in order to provide as many degrees of freedom as possible in terms of deceleration of the vehicle. Modern disc, drum and rim brakes, which are operated by cable or hydraulically operated, can achieve high braking delays, which exacerbate the problems described above. To make matters worse, straight electrically operated two-wheelers always reach higher average speeds and the risk of accidents increases.

The braking force of bicycle brakes is conventionally limited only by the frictional limit between the tire and the ground and the maximum force that can be applied by the driver manual force. This can cause wheels to be locked in bicycles in critical driving situations. A blocking rear wheel is largely uncritical for stability reasons. However, since a high braking force on a front wheel usually initially leads to a lifting of the rear wheel and only later to a blocking of the front wheel, at full braking the risk of a rollover threatens. Furthermore, locking the front wheel may cause the bike to become unmanageable and may fall.

As a consequence, inexperienced cyclists usually brake too weakly and do not take advantage of the full deceleration potential of the bicycle brake. This behavior can extend the braking distance even in emergency situations. The publication DE 101 58 382 A1 discloses an anti-lock brake system for bicycles which employs a sensor, a battery powered controller, and a hydraulic actuator. In the hydraulic actuator is dispensed with a return pump for the hydraulic fluid in a storage chamber.

In the publication DE 10 2010 038 525 A1 A hydraulic braking device for light single-track vehicles, such as bicycles and pedelecs, with an active braking force limitation is described. In a hydraulic system of the brake device, a piezo stack is arranged. By changing the volume of the piezo stack, a fluid pressure in the hydraulic system can be varied. A blocking of a wheel or a rollover should be prevented by targeted activation of the piezo stack.

The publication US 2012/0305345 A1 discloses a portable brake assist system in which an electronic controller detects a wheel lock and applies an additional brake force limit to the brake mechanism via an external actuator.

However, there is a need for improved brake assist systems with high reliability and ease of construction, particularly in electrically powered two-wheeled vehicles.

Disclosure of the invention

According to a first aspect of the invention, an actuator device for a hydraulic brake device of a vehicle, in particular a two-wheeled vehicle such as an electrically operable bicycle, comprises a hydraulic brake cylinder having a first cylinder chamber and a second cylinder chamber fluidly separated from the first cylinder chamber, each with hydraulic fluid are filled, arranged in the brake cylinder between the first cylinder chamber and the second cylinder chamber piston device, which is adapted to transmit upon application of the hydraulic fluid in the first cylinder chamber with pressure, so by pressurizing, a pressure on the hydraulic fluid in the second cylinder chamber, a control device, and a dielectric elastomer actuator, which can be acted upon by the control device with an electric field, and which in Dependent on the applied electric field is expandable and / or compressible, wherein the dielectric elastomer actuator is adapted to reduce the pressure on the hydraulic fluid in the second cylinder chamber when subjected to an electric field.

According to a second aspect of the invention, a vehicle comprises at least one wheel for drivingly supporting the vehicle on a ground, a hydraulic braking device disposed on the wheel and adapted to reduce the rotational speed of the wheel, an operating device, an actuator device According to the first aspect of the invention, a first hydraulic line, which sets the operating device in hydraulic operative connection with the first cylinder chamber of the actuator device, and a second hydraulic line, which sets the second cylinder chamber of the actuator device in hydraulic operative connection with the braking device.

According to a third aspect of the invention, a method for actuating a hydraulic brake of a vehicle according to the second aspect of the invention comprises the steps of determining an initiated braking operation with the brake of the vehicle, determining movement parameters of the vehicle by evaluating yaw rates of the vehicle, rotational speeds of the vehicle Wheels of the vehicle and / or instantaneous acceleration of the vehicle, comparing the determined movement parameters of the vehicle with a predeterminable motion profile, and the driving of the actuator device for reducing the pressure of the hydraulic fluid in the second cylinder chamber.

Advantages of the invention

The idea underlying the present invention is to provide an electrically operable brake assist for a vehicle, with which the braking force of the vehicle can be regulated in dependence on movement parameters of the vehicle. For this purpose, actuators are provided in an actuator device based on electroactive polymers, and in particular dielectric elastomers, which in addition to the applied by the driver of the vehicle via a hydraulic active connection to a hydraulic braking device braking force by corresponding variation of the driving voltage of the dielectric elastomers additional braking forces on the hydraulic braking device can muster.

The arrangement of the actuator or the actuators in the actuator device can be chosen such that an anti-lock functionality (short, an ABS function) can be achieved. Due to the mechanical design, the actuator device is particularly well suited to a lightweight vehicle, such as a lightweight two-wheeler such as a muscle-powered bicycle, an e-bike or a pedelec with electric drive or electric auxiliary drive, or a moped, with an easy-to-implement, cost-effective, reliable and automatic anti-lock functionality.

The realization of an ABS function makes it possible to avoid locking the wheel or wheels of the vehicle and possibly resulting loss of control over the vehicle. If the vehicle is single-lane and the front wheel of the vehicle is selected as the wheel to be assisted, then with the actuator device a rollover of the driver over the handlebar can be prevented with excessively strong braking. However, the invention may also be useful in light multi-lane vehicles - such as muscle-powered, rickshaw-type companions with more than two wheels - to prevent, for example, skidding when locking the wheels.

The actuators with dielectric elastomers can be powered by an already existing electrical power supply of the vehicle with energy. Therefore, the actuator device is particularly suitable for vehicles with an electric power source such as e-bikes or pedelecs. The actuator device contributes to the improvement of the driving characteristics of the vehicle and allows an optimal distribution of braking force, which can have a favorable effect on the braking distance. The active braking force limitation by the actuator device in the hydraulic system of the vehicle is effected via a volume change in the cylinder chambers or the hydraulic lines of the hydraulic system and a concomitant fluid pressure change in the hydraulic system. In this case, the active brake force limitation is controlled by a controller in response to the detection of a critical driving condition of the vehicle.

By sensing suitable vehicle data such as a wheel speed of the front wheel and / or the rear wheel of a bicycle or the wheel contact force of the rear wheel or similar vehicle data that can indicate a critical driving condition of the vehicle, by targeted driving the arranged in the actuator device Elastomeraktors a closed loop can be implemented, for example, with the aid of which prevents blocking of a wheel of the vehicle and / or a rollover protection for the vehicle can be realized.

In the proposed hydraulic brake device, a braking force For example, from a brake lever that can be operated by a vehicle driver and can press on serving as a donor brake cylinder piston, transmitted to a standing in contact with a brake pad brake device. When the braking force is applied, the brake pad is pressed, for example, against the rim of a wheel or a brake disc firmly connected to the wheel, and thus achieves a braking effect for the vehicle. Too high a braking force can lead to a locking of the wheel. Furthermore, too high a braking force, which acts on a front wheel, for example, a bicycle, cause the rear wheel lifts and there may be a rollover of the vehicle.

Upon detection of a critical driving condition, for example blocking of the front wheel or lifting of the rear wheel, control can be intervened in the hydraulic system by the control by briefly and temporarily releasing the braking device by actuating the elastomer actuator. The elastomer actuator may be designed in terms of active area, expansion and material properties such that a maximum achievable expansion or compression of the elastomer actuator upon application of a predetermined electric field strength corresponds to a volume change that allows the fluid pressure in the hydraulic lines or cylinder chambers to be in one to be able to vary predetermined range, which is appropriate for typical applications during braking operations of the vehicle.

For example, the elastomer actuator may also be provided with a gear ratio that is configured to translate expansion of the elastomer actuator into a change in volume available within the hydraulic system for a hydraulic fluid. In other words, a translation device can be provided which can transform a strain or compression caused by the elastomer actuator into a larger or smaller volume change within the hydraulic system. This can for example be achieved by a suitable mechanism which is in contact with the elastomer actuator on one side and on the other side with the volume of the hydraulic system to be changed within the second cylinder chamber or the second hydraulic line.

Advantageous embodiments and developments of the invention will become apparent from the dependent claims and from the description with reference to the figures.

According to an embodiment of the actuator device, the actuator device may further comprise an actuator housing, an actuator piston movable in the actuator housing, and an actuator hydraulic line which is coupled to the second cylinder chamber via a valve. In this case, the dielectric elastomer actuator can be connected to a rear wall of the actuator housing and the actuator piston.

According to a further embodiment of the actuator device, the control device can be designed to apply an electric field to the dielectric elastomer actuator so that the dielectric elastomer actuator moves the actuator piston toward the rear wall of the actuator housing by compression and thereby discharges hydraulic fluid from the second cylinder chamber into the actuator hydraulic line ,

According to another embodiment of the actuator device, the controller may be configured to apply and thereby stretch the dielectric elastomer actuator with an electric field as well as keeping the valve closed and thereafter opening the valve and simultaneously applying the electric field from the dielectric elastomer actuator remove, so that the dielectric elastomer actuator by expansion moves the actuator piston in the direction of the rear wall of the actuator housing, thereby deriving hydraulic fluid from the second cylinder chamber in the Aktorhydraulikleitung.

According to a further embodiment of the actuator device, the piston device may comprise a first movable piston plate, which fluidly seals the first cylinder chamber, and a second movable piston plate which is mechanically operatively connected to the first piston plate and which seals the second cylinder chamber in a fluid-tight manner. In this case, the dielectric elastomer actuator between the first piston plate and the second piston plate may be arranged in the hydraulic brake cylinder.

According to a further embodiment of the actuator device, the dielectric elastomer actuator may be respectively mechanically fixedly connected to the first piston plate and the second piston plate. In one embodiment, the control device can be designed to apply an electric field to the dielectric elastomer actuator and thereby pull the second piston plate in the direction of the first piston plate.

According to a further embodiment of the actuator device, the piston device may further comprise a third fixedly in the brake cylinder piston plate which is disposed between the first piston plate and the second piston plate, and a piston rod which is guided through the third piston plate, and which the first piston plate and the second Piston plate mechanically rigidly interconnects. In one variant, the dielectric elastomer actuator may in each case be mechanically fixedly connected to the first piston plate and the third piston plate, and the control device may be designed to apply an electric field to the dielectric elastomer actuator and thereby move the first piston plate away from the third piston plate to press.

According to one embodiment of the vehicle, the vehicle may have a plurality of wheels, wherein each of the wheels of the vehicle is equipped with a braking device and an actuator device according to the invention.

According to a further embodiment of the vehicle, the vehicle may further comprise an electrical power supply device which is coupled to the actuator device and the control device and which is designed to supply the actuator device and the control device with electrical energy. This is particularly advantageous in pedelecs and electrically operable bicycles, which in any case lead to a battery or other electrical storage unit for the provision of electrical energy for the drive.

According to a further embodiment of the vehicle, the control device may further comprise an acceleration sensor, a rotation rate sensor, a rotational speed sensor and / or a compression travel sensor. The control device can monitor the driving state of the vehicle via one or more of these sensors and, if necessary, detect critical driving situations such as a roll, a blocking of the brakes, an undesired tilting about a wheel axle or the like by plausibility checking of the sensor measured values. This allows the initiation of appropriate countermeasures via a programmed control of the actuator device (s).

According to an embodiment of the method for actuating a hydraulic brake of a vehicle, the driving of the actuator device may comprise a change of the electric field strength at the dielectric elastomer actuator by the control device.

The above embodiments and developments can, if appropriate, combine with each other as desired. Further possible refinements, developments and implementations of the invention also include combinations of features of the invention which have not been explicitly mentioned above or described below with regard to the exemplary embodiments.

Brief description of the drawings

The invention will be explained in more detail with reference to the exemplary embodiments indicated in the schematic figures. It show here:

1 a schematic block diagram of a hydraulic brake with an actuator device according to an embodiment of the invention;

2 a detailed view of an actuator device for a hydraulic brake of a vehicle according to another embodiment of the invention;

3 a detailed view of another actuator device for a hydraulic brake of a vehicle according to another embodiment of the invention;

4 a detailed view of another actuator device for a hydraulic brake of a vehicle according to yet another embodiment of the invention;

5 a schematic illustration of a vehicle with a hydraulic brake and an actuator device according to another embodiment of the invention; and

6 a schematic illustration of a block diagram for the flow of a method according to another embodiment of the invention.

The accompanying drawings are provided for a better understanding of the present invention and illustrate exemplary embodiments of the invention. They serve to explain principles, advantages, technical effects and possible variations. Of course, other embodiments and many of the intended advantages of the invention are also conceivable, particularly with a view to the following detailed description of the invention. The elements in the drawings are not necessarily drawn to scale and for reasons of clarity partly simplified or schematized. The same reference numerals designate the same or similar components or elements.

Although specific embodiments are described and illustrated herein, it will be apparent to those skilled in the art that a plethora of other, alternative and / or equivalent implementations may be selected for the embodiments without substantially departing from the spirit of the present invention. In general, all variations, modifications and Variations of the embodiments described herein are also considered to be covered by the invention.

1 shows a schematic block diagram of a brake with an actuator device 23 , Shown is a designed as a front wheel first wheel 2 a only partially shown, designed as a bicycle single-track vehicle. The first bike 2 serves the mobile support of the vehicle on a ground and is about a rotation axis 3 rotatable on a component 4 of the vehicle, here a bicycle fork, stored. For this purpose, the first wheel 2 a wheel hub 5 on.

The rotational speed of the first wheel 2 can by means of a braking device 22 be reduced. So that a driver of the vehicle, the braking device 22 can operate is an operating device 11 provided, for example, a brake lever, which may be arranged on a handlebar of the vehicle. The operating device 11 is via a first hydraulic brake line 21 , an actuator device 23 and a second hydraulic brake line 24 with the braking device 22 hydraulically operatively connected, by means of which a driver on the operating device 11 applied force on the braking device 22 can be transferred. The braking device 22 can - as in 1 exemplified - be a shoe brake or rim brake. Alternatively, it may also be possible for the braking device 22 form as a disc brake or drum brake.

Simultaneously with the operation of the braking device 22 can by means of the operating device 11 Also, not shown brake devices together with the braking device 22 be actuated, for example, another type of brake on the same wheel 2 or another braking device on another not shown wheel of the vehicle. These further brake devices may optionally have additional hydraulic brake lines 21 with the operating device 11 be connected. The braking device 22 is in 1 indicated only schematically, but is arranged so that it is on a rim of the first wheel 2 acts when an operation by means of the operating device 11 takes place, whereby a braking force is applied to the rim. The means of braking device 22 on the rim and thus on the first wheel 2 Applicable braking force - and thus also the braking torque, which is the first wheel 2 due to the operation of the braking device 22 learns - can by the actuator device 23 be limited in a manner described in more detail below.

The 2 . 3 and 4 show schematic illustrations of actuator devices 23 , which for a hydraulic brake according to 1 can be used. Common is all actuator devices 23 of the 2 . 3 and 4 a hydraulic brake cylinder 31 , which is a first cylinder chamber 37 and one of the first cylinder chamber 37 fluidly separated second cylinder chamber 38 has, which are each filled with hydraulic fluid H. The first cylinder chamber 37 is with the first hydraulic line 21 in hydraulic operative connection, while the second cylinder chamber 38 in hydraulic operative connection with the second hydraulic line 24 stands. In the brake cylinder 31 is between the first cylinder chamber 37 and the second cylinder chamber 38 arranged a piston device. This serves to transmit pressure to the hydraulic fluid H in the first cylinder chamber 37 on pressure on the hydraulic fluid H in the second cylinder chamber 38 ,

The brake cylinder 31 may be part of a comprehensive (not explicitly shown) hydraulic system in which with the aid of a fluid such as an oil as the hydraulic fluid H, a fluid pressure can be transmitted within a conduit system. By varying the fluid pressure corresponding brake piston in the brake device 22 Brake elements for initiating a braking deceleration on the wheel 2 to be moved.

A control device 7 serves to actuate an actuator with electroactive polymers, which is part of the actuator device 23 is. The actuator is in each case a dielectric elastomer actuator which comprises a dielectric elastomer body 34 comprises, which can be acted upon in a spatial direction with an electric field, for example by the application of an electrical voltage between two opposite and on the side surfaces of the elastomer body 34 arranged electrodes 32 and 33 , The elastomer body 34 may for example be a few hundred micrometers to a few millimeters thin elastomeric film whose thickness is compressed by the application of the electric field. As a result, the elastomeric body expands 34 in a direction perpendicular to the field direction spatial direction.

The control device 7 can apply an electric field to the dielectric elastomer actuator so that it can expand or compress depending on the applied electric field. In general, the dielectric elastomer actuator in each of the 2 . 3 and 4 designed so that when subjected to an electric field, the movement of the actuator, such as an expansion or compression, the pressure on the hydraulic fluid H in the second cylinder chamber 38 can diminish.

2 shows a detailed illustration of an exemplary actuator device 23 , The actuator device 23 comprises a piston device with a first, in the brake cylinder housing movably mounted piston plate 35 , which is the first cylinder chamber 37 opposite the second cylinder chamber 38 fluidly sealed. In addition, the piston device comprises a second, in the brake cylinder housing movably mounted piston plate 36 that with the first piston plate 35 is mechanically operatively connected and is substantially plane-parallel to this. The second piston plate 36 in turn closes the second cylinder chamber 38 opposite the first cylinder chamber 37 fluidly tight. The piston actuating direction of the piston plates 35 and 36 takes place substantially along the extension direction of the brake cylinder 31 (x-direction) and in the plane normal direction of the piston plates 35 . 36 , Between the first piston plate 35 and the second piston plate 36 is in the hydraulic brake cylinder 31 arranged a dielectric elastomer actuator.

The elastomer body 34 of the dielectric elastomer actuator is with the electrodes 32 and 33 having side surfaces each mechanically fixed to the first piston plate 35 or the second piston plate 36 connected. The control device 7 can be an operating voltage to the electrodes when the ABS system is activated 32 and 33 create so that the elastomeric body 34 contracts in the y-direction and thus expands in the x-direction. Upon application of a fluid pressure to the hydraulic fluid H in the first cylinder chamber 37 the hydraulic fluid H becomes the piston device in the direction of the second cylinder chamber 38 push, that is, in the positive x-direction, so as to the fluid pressure to the second cylinder chamber 38 transferred to. This will be via the hydraulic line 24 a braking operation, for example with the braking device 22 of the 1 , initiated. The movement of the piston device in the positive x-direction also causes the elastomer body 34 of the dielectric elastomer actuator between the piston plates 35 and 36 with postponed.

If the braking deceleration caused thereby on the braked wheel, for example the front wheel of a vehicle, is too great, the rear wheel can lift off the road and a rollover of the vehicle threatens. When such a situation is detected, for example by the controller 7 with appropriate sensors, can via the actuator device 23 of the 2 Countermeasures are initiated. An impending rollover is characterized for example by a high speed difference between the front and rear wheels, a high rate of rotation of the entire vehicle or a change in direction of the acceleration vector of the vehicle.

Now, if a critical driving situation is detected, the first piston plate 35 in the brake cylinder housing of the brake cylinder 31 jammed or mechanically locked. The control device 7 may then be designed to be the voltage between the electrodes 32 and 33 so that the elastomer body contracts again in the x-direction or reduces the elongation. This will cause the second piston plate 36 in the direction of the first (now fixed) piston plate 35 drawn. This means that the fluid pressure in the second cylinder chamber 38 reduced and the brake is released.

When the critical driving situation is completed, the locking of the first piston plate 35 be solved and the controller 7 the voltage between the electrodes 32 and 33 increase again. When releasing care should be taken that the driver of the vehicle with the actuator device 23 gently reengaged into the braking device by releasing the cobra plate 35 the fluid pressure in both cylinder chambers 37 and 38 should be about the same, so no jerky braking occurs and the driver is not afraid.

3 shows a detailed illustration of another exemplary actuator device 23 , The actuator device 23 comprises a piston device with a first, in the brake cylinder housing movably mounted piston plate 35 , which is the first cylinder chamber 37 opposite the second cylinder chamber 38 fluidly sealed. In addition, the piston device comprises a second, in the brake cylinder housing movably mounted piston plate 36 that with the first piston plate 35 is mechanically operatively connected and is substantially plane-parallel to this. The second piston plate 36 in turn closes the second cylinder chamber 38 opposite the first cylinder chamber 37 fluidly tight. The piston actuating direction of the piston plates 35 and 36 takes place substantially along the extension direction of the brake cylinder 31 (x-direction) and in the plane normal direction of the piston plates 35 . 36 , Between the first piston plate 35 and the second piston plate 36 is in the hydraulic brake cylinder 31 arranged a dielectric elastomer actuator.

Unlike in the example of 2 is still a third in the piston device, fixed in the brake cylinder 31 anchored piston plate 39 includes. This is between the first piston plate 35 and the second piston plate 36 arranged. The mechanical working connection is in 3 through a piston rod 30 mediated by the third piston plate 39 passed through, and which the first piston plate 35 and the second piston plate 36 mechanically rigidly interconnects. In addition, in the normal operating mode, there is no voltage between the electrodes 32 and 33 created.

The elastomer body 34 of the dielectric elastomer actuator is with the electrodes 32 and 33 having side surfaces each mechanically fixed to the first piston plate 35 or the third piston plate 39 connected. Upon application of a fluid pressure to the hydraulic fluid H in the first cylinder chamber 37 the hydraulic fluid H becomes the piston device in the direction of the second cylinder chamber 38 push, that is, in the positive x-direction, so as to the fluid pressure to the second cylinder chamber 38 transferred to. This will be via the hydraulic line 24 a braking operation, for example with the braking device 22 of the 1 , initiated. The movement of the piston device in the positive x-direction also causes the elastomer body 34 of the dielectric elastomer actuator between the piston plates 35 and 39 compressed.

If the braking deceleration caused thereby on the braked wheel, for example the front wheel of a vehicle, is too great, the rear wheel can lift off the road and a rollover of the vehicle threatens. When such a situation is detected, for example by the controller 7 with appropriate sensors, can via the actuator device 23 of the 3 Countermeasures are initiated. An impending rollover is characterized for example by a high speed difference between the front and rear wheels, a high rate of rotation of the entire vehicle or a change in direction of the acceleration vector of the vehicle.

Now, if a critical driving situation is detected, the control device 7 be designed to be a voltage between the electrodes 32 and 33 be applied so that the elastomer body expands again in the x-direction or reduces the compression. This will be the first piston plate 35 from the third (fixed) piston plate 39 pressed away. That means the second piston plate 36 due to the rigid piston rod 30 also in the direction of the third piston plate 39 is pulled and the fluid pressure in the second cylinder chamber 38 reduces what the brake releases. When the critical driving situation has ended, the control device 7 the voltage between the electrodes 32 and 33 reduce again or set to zero.

4 shows a schematic representation of another exemplary actuator device 23 , The actuator device 23 comprises a piston device with only one piston plate 35 , which the pressure transfer between the two cylinder chambers 37 and 38 taught. The actuator device 23 but includes an actuator housing 40 with one in the actuator housing 40 movably mounted actuator piston 41 , Between a rear wall of the actuator housing 40 and the actuator piston 41 is a dielectric elastomer actuator with elastomeric body 34 arranged so that the side surfaces with electrodes 32 and 33 in each case on the rear wall or the actuator piston 41 mechanically firmly connected. On the actuator side of the actuator piston 41 there is an actuator hydraulic line 42 with hydraulic fluid H, which communicates with the second cylinder chamber 38 via a valve 43 is coupled. The valve 43 may be, for example, a 2/2-way valve.

Upon application of a fluid pressure to the hydraulic fluid H in the first cylinder chamber 37 the hydraulic fluid H becomes the piston plate 35 in the direction of the second cylinder chamber 38 push, that is, in the positive x-direction, so as to the fluid pressure to the second cylinder chamber 38 transferred to. This will be via the hydraulic line 24 a braking operation, for example with the braking device 22 of the 1 , initiated.

If the braking deceleration caused thereby on the braked wheel, for example the front wheel of a vehicle, is too great, the rear wheel can lift off the road and a rollover of the vehicle threatens. When such a situation is detected, for example by the controller 7 with appropriate sensors, can via the actuator device 23 of the 4 Countermeasures are initiated. An impending rollover is characterized for example by a high speed difference between the front and rear wheels, a high rate of rotation of the entire vehicle or a change in direction of the acceleration vector of the vehicle.

Now, if a critical driving situation is detected, the piston plate can first 35 mechanically in the brake cylinder housing of the brake cylinder 31 locked or jammed. There valve 43 initially remains closed while the controller 7 , a voltage between the electrodes 32 and 33 applies to the elastomeric body 34 to stretch in y-direction and the actuator piston 41 to deflect in positive y-direction. When the elastomer actuator has stabilized, the controller may 7 the valve 43 open and the actuator hydraulic line 42 fluidic with the hydraulic line 24 connect. When the controller 7 again reduces the voltage across the dielectric elastomer actuator, becomes the elastomeric body 34 by compression or expansion of the actuator piston 41 in the direction of the rear wall of the actuator housing 40 move and thereby hydraulic fluid H from the second cylinder chamber 38 or the hydraulic line 24 in the actuator hydraulic line 42 derived.

When the critical driving situation is completed, the locking of the first piston plate 35 be solved and the controller 7 the voltage between the electrodes 32 and 33 increase again. Thereby, the hydraulic fluid H turns off the actuator hydraulic line 42 back into the hydraulic line 24 fed back. After that, the valve can 43 closed again and the voltage between the electrodes 32 and 33 be reduced again or reduced to zero. When releasing care should be taken that the driver of the vehicle with the actuator device 23 gently reengaged into the braking device by releasing the cobra plate 35 the fluid pressure in both cylinder chambers 37 and 38 should be about the same, so no jerky braking occurs and the driver is not afraid.

With the actuator devices 23 of the 2 . 3 and 4 An ABS function can be implemented in each case: If blocking one or more with actuator devices 23 equipped wheels is detected, the respective dielectric elastomer actuator can be selectively expanded or compressed by applying appropriate voltages to temporarily interrupt the blockage of the wheel or wheels. For example, a "stutter braking" can be implemented in a known manner.

5 shows a designed as a bicycle single-track vehicle 200 with a frame 201 , a front link 202 and a first bike 2 and a second wheel 203 , The vehicle 200 of the 5 moves in the direction of arrow F on a surface, the angular velocities of the wheels 2 . 203 are designated W2 and W203. The vehicle 200 has, for example, at least one braking device, for example a braking device 13 at the first wheel 2 of the vehicle 200 , in 5 the front wheel, and / or a braking device 22 at the second wheel 203 , in 5 the rear wheel. In the example of 5 is the limit of braking force or braking torque of the two braking devices 13 and 22 in the same way as in relation to the 2 to 4 explained possible. For this purpose, two actuator devices 23 can be used, which established the rim brake brake device 22 and the brake device configured as a disc brake 13 can actuate. The frame 201 For example, the vehicle may be at least partially used as an actuator housing for the actuator devices 23 serve, that is, the actuator devices 23 can either be separate, on the frame 201 fixed components are provided, or at least partially in the frame 201 be formed.

The vehicle 200 may further comprise a power supply device 6 have, for example, an accumulator or a battery. The power supply device 6 can be used to the elastomeric actuators 32 . 33 . 34 the actuator device (s) 23 with electrical energy to act on the elastomer actuators 32 . 33 . 34 to supply with electrical voltage. In addition, the vehicle, the control device 7 having, which with the power supply device 6 connected and supplied from this with electrical energy. The control device 7 may be configured to control the operation of the actuator device (s) 23 to control how in terms of the 1 to 4 explained.

For this purpose, it may be provided that the control device 7 has one or more position or motion sensors, such as acceleration sensors, yaw rate sensors, speed sensors or compression travel sensors.

For example, can be detected by means of a rotation rate sensor or a speed sensor when the angular velocity of a monitored wheel 2 . 203 falls below a minimum threshold, from which it can be concluded that the wheel 2 . 203 tends to block. Further, it may be inferred from the speed with which an angular velocity changes, whether it is a regular braking operation or an unwanted locking of a wheel 2 . 203 , Further, by comparing angular velocities of two at different wheels of the vehicle 200 mounted rate of rotation or wheel speed sensors are measured, a tendency to lock a wheel 2 . 203 getting closed.

An acceleration sensor may be used to detect acceleration of the vehicle 200 be used to detect a critical driving condition. For example, an acceleration sensor may measure an acceleration by determining an inertial force acting on a test mass. Furthermore, piezoceramic sensor plates can be used, which can convert dynamic pressure fluctuations into electrical signals, micro-electromechanical sensors (MEMS) based on silicon wafers, strain gauges or magnetic induction sensors. Such an acceleration sensor can be used for example for detecting a vertical acceleration, that is, an acceleration transverse to the typical direction of travel of the vehicle 200 , For example, with such an acceleration sensor in a bicycle that normally moves horizontally, it can be recognized when the rear wheel is accelerated in a vertical direction. From this it can be concluded that the bicycle tends to overturn.

About the provided by the sensors position, position and / or movement parameters, the control device 7 a movement situation of the vehicle 200 determine. The control device 7 can initiate a braking process with the braking devices 13 and or 22 of the vehicle 200 detect, for example, over Changes in the speed of the wheels 2 and 203 or the acceleration values of the vehicle 200 , Thereafter, the control device 7 Movement parameters of the vehicle 200 by evaluating the rate of rotation of the vehicle 200 , Speeds of the wheels 2 and 203 of the vehicle 200 and / or instantaneous acceleration values of the vehicle 200 determine. The determined motion parameters of the vehicle 200 can then, for example, with a predeterminable motion profile, which in an internal memory of the control device 7 stored can be adjusted. The provided parameters of the individual sensors can each other for plausibility of the detected state of motion of the vehicle 200 be used. Should turn out after reconciliation that a potential danger situation for the driver of the vehicle 200 prevails or threatens, the control device 7 the necessary control signals to the actuator device (s) 23 for temporarily reducing the power transmission to the hydraulic braking device 13 and or 22 to transfer.

6 shows a method M for actuating a hydraulic brake ( 13 ; 22 ) of a vehicle, such as a hydraulic brake 13 or 22 of a vehicle 200 as in 5 shown. The method M can, for example, by means of an actuator device 23 as in terms of the 2 to 4 be explained explained.

In a first step M1, a determination is made of an initiated braking process with the brake 13 respectively. 22 of the vehicle 200 , This is followed in step M2 by determining movement parameters of the vehicle 200 by evaluating the rate of rotation of the vehicle 200 , Speeds of the wheels of the vehicle 200 and / or instantaneous acceleration of the vehicle 200 , The determined motion parameters of the vehicle 200 are compared in step M3 with a predeterminable motion profile, so that in step M4 an actuator device 23 for reducing the pressure of the hydraulic fluid in a second cylinder chamber 38 the actuator device 23 can be controlled, for example, by appropriately changing the electric field strength at one in the actuator device 23 arranged dielectric elastomer actuator.

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

• DE 10158382 A1 [0005]
• DE 102010038525 A1 [0006]
• US 20120305345 A1 [0007]

Claims (13)

Actuator device ( 23 ) for a hydraulic brake ( 13 ; 22 ) of a vehicle ( 200 ), comprising: a hydraulic brake cylinder ( 31 ), which a first cylinder chamber ( 37 ) and one of the first cylinder chamber ( 37 ) fluidically separated second cylinder chamber ( 38 ), each filled with hydraulic fluid (H); one in the brake cylinder ( 31 ) between the first cylinder chamber ( 37 ) and the second cylinder chamber ( 38 ) arranged piston device, which is adapted upon application of the hydraulic fluid (H) in the first cylinder chamber ( 37 ) a pressure on the hydraulic fluid (H) in the second cylinder chamber ( 38 ) transferred to; a control device ( 7 ); and a dielectric elastomer actuator ( 32 . 33 . 34 ), which by the control device ( 7 ) is acted upon by an electric field, and which is extensible and / or compressible in dependence on the applied electric field, wherein the dielectric elastomer actuator ( 32 . 33 . 34 ) is adapted, when subjected to an electric field, the pressure on the hydraulic fluid (H) in the second cylinder chamber ( 38 ). Actuator device ( 23 ) according to claim 1, further comprising: an actuator housing ( 40 ); one in the actuator housing ( 40 ) movable actuator piston ( 41 ); and an actuator hydraulic line ( 42 ), which with the second cylinder chamber ( 38 ) via a valve ( 43 ), wherein the dielectric elastomer actuator ( 32 . 33 . 34 ) with a rear wall of the actuator housing ( 40 ) and the actuator piston ( 41 ) connected is. Actuator device ( 23 ) according to claim 2, wherein the control device ( 7 ) is adapted to the dielectric elastomer actuator ( 32 . 33 . 34 ) to apply an electric field so that the dielectric elastomer actuator ( 32 . 33 . 34 ) by compression of the actuator piston ( 41 ) in the direction of the rear wall of the actuator housing ( 40 ) and thereby hydraulic fluid (H) from the second cylinder chamber ( 38 ) into the actuator hydraulic line ( 42 ). Actuator device ( 23 ) according to claim 2, wherein the control device (16) is adapted to control the dielectric elastomer actuator (10). 32 . 33 . 34 ) with an electric field to act and thereby stretch and the valve ( 43 ) at the same time, and then the valve ( 43 ) and at the same time the electric field from the dielectric elastomer actuator ( 32 . 33 . 34 ), so that the dielectric elastomer actuator ( 32 . 33 . 34 ) by expansion of the actuator piston ( 41 ) in the direction of the rear wall of the actuator housing ( 40 ) and thereby hydraulic fluid (H) from the second cylinder chamber ( 38 ) into the actuator hydraulic line ( 42 ). Actuator device ( 23 ) according to claim 1, wherein the piston device comprises: a first movable piston plate ( 35 ), which the first cylinder chamber ( 37 ) closes fluidly tight; and a second movable piston plate ( 36 ), which with the first piston plate ( 35 ) is mechanically operatively connected, and which the second cylinder chamber ( 38 ) fluidly seals, wherein the dielectric elastomer actuator ( 32 . 33 . 34 ) between the first piston plate ( 35 ) and the second piston plate ( 36 ) in the hydraulic brake cylinder ( 31 ) is arranged. Actuator device ( 23 ) according to claim 5, wherein the dielectric elastomer actuator ( 32 . 33 . 34 ) each mechanically fixed to the first piston plate ( 35 ) and the second piston plate ( 36 ), and wherein the control device ( 7 ) is adapted to the dielectric elastomer actuator ( 32 . 33 . 34 ) to apply an electric field and thereby the second piston plate ( 36 ) in the direction of the first piston plate ( 35 ) to draw. Actuator device ( 23 ) according to claim 5, wherein the piston device further comprises: a third fixed in the brake cylinder ( 31 ) anchored piston plate ( 39 ), which between the first piston plate ( 35 ) and the second piston plate ( 36 ) is arranged; and a piston rod ( 30 ), which through the third piston plate ( 39 ), and which the first piston plate ( 35 ) and the second piston plate ( 36 ) mechanically rigidly interconnects, wherein the dielectric elastomer actuator ( 32 . 33 . 34 ) each mechanically fixed to the first piston plate ( 35 ) and the third piston plate ( 39 ), and wherein the control device ( 7 ) is adapted to the dielectric elastomer actuator ( 32 . 33 . 34 ) to apply an electric field and thereby the first piston plate ( 35 ) from the third piston plate ( 39 ) to push away. Vehicle ( 200 ), with: at least one wheel ( 2 ; 203 ) for movably supporting the vehicle ( 200 ) on a surface; a hydraulic braking device ( 13 ; 22 ), which on the wheel ( 2 ; 203 ) and which is adapted to reduce the rotational speed (W2; W203) of the wheel; an operating device ( 11 ); an actuator device ( 23 ) according to any one of claims 1 to 7; a first hydraulic line ( 21 ), which the control device ( 11 ) in hydraulic operative connection with the first cylinder chamber ( 37 ) of the actuator device ( 23 ) puts; and a second hydraulic line ( 24 ), which the second cylinder chamber ( 38 ) of the actuator device ( 23 ) in hydraulic operative connection with the braking device ( 13 ; 22 ) puts. Vehicle ( 200 ) according to claim 5, wherein the vehicle ( 200 ) several wheels ( 2 . 203 ), each of the wheels ( 2 . 203 ) of the vehicle ( 200 ) with a hydraulic braking device ( 13 ; 22 ) and an actuator device ( 23 ) is equipped according to one of claims 1 to 7. Vehicle ( 200 ) according to one of claims 8 and 9, further comprising: an electrical power supply device ( 6 ) connected to the actuator device ( 23 ) and the control device ( 7 ) and which is adapted to operate the actuator device ( 23 ) and the control device ( 7 ) to provide electrical energy. Vehicle ( 200 ) according to one of claims 8 to 10, wherein the control device ( 7 ) further comprises an acceleration sensor, a rotation rate sensor, a speed sensor and / or a compression travel sensor. Method (M) for actuating a hydraulic brake ( 13 ; 22 ) of a vehicle ( 200 ) according to one of claims 8 to 11, comprising the steps of: determining (M1) an initiated braking process with the brake ( 13 ; 22 ) of the vehicle ( 200 ); Determining (M2) motion parameters of the vehicle ( 200 ) by evaluating rates of rotation of the vehicle ( 200 ), Speeds of wheels ( 2 ; 203 ) of the vehicle ( 200 ) and / or instantaneous acceleration of the vehicle ( 200 ); Compare (M3) the determined motion parameters of the vehicle ( 200 ) with a predeterminable movement profile; and driving (M4) the actuator device ( 23 ) for reducing the pressure of the hydraulic fluid in the second cylinder chamber ( 38 ). Method (M) according to claim 12, wherein the driving (M4) of the actuator device ( 23 ) changing the electric field strength at the dielectric elastomer actuator ( 32 ; 33 ; 34 ) by the control device ( 7 ).

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