DE102008037720A1 - Hydraulically acting brake system for vehicle, has master brake cylinder, whose working space is connected with wheel brake or parking brake of vehicle by hydraulic line - Google Patents

Abstract

The hydraulically acting brake system has a master brake cylinder, whose working space is connected with a wheel brake or parking brake of the vehicle by a hydraulic line. An actuator adjusts a brake lining (52) of a wheel brake for attaining a clearance. The actuator is a spring, which is preloaded particularly by the actuator. An independent claim is included for a method using a hydraulically acting brake system.

Description

State of the art

The The invention relates to a hydraulically acting brake system with a Master cylinder whose at least one working space above at least one hydraulic line with at least one wheel brake or Parkierbremse the vehicle is connected.

After braking, especially in brake systems with disc brakes, creates a residual braking effect, since the restoring forces on the brake piston are not sufficient to lift the brake pads sufficiently far from the brake disc. To solve this problem, among other things, a roll-back seal has been developed, which moves the brake piston and with him the brake pad from the brake disc after the completion of braking. However, the roll-back capability of the sealing ring is limited to the brake piston and is not sufficient to fully compensate for soiling, aging and elastic deformation in the caliper and friction linings. Remedies with an air gap between brake pad and brake disc / brake piston are in DE 44 18 701 and DE 196 01 434 described. The proposed solutions according to the aforementioned documents have not been introduced, since the additional effort in relation to the effect is unsatisfactory and also occurs through the set air clearance during subsequent braking a pedal travel loss, which adversely the braking distances are at full braking longer.

According to the current state of development of the brakes, mid-range vehicles on the test bench to determine the NEDC consumption have an additional consumption of approx. 0.251 = 6 g CO ₂ / km due to the residual braking effect mentioned above. This value applies to a new vehicle without aging and is significant considering the future CO ₂ targets.

task The present invention is therefore a hydraulically acting To further develop brake system to the effect that the residual braking effect safely avoided.

These The object is achieved according to the invention an actuator at least one brake pad of a wheel brake for Achieving a clearance adjusted. Further advantageous Embodiments of the brake system according to the invention according to claim 1 result from the features of the subclaims.

Of the Invention is based on the idea that an actuator, which actively controllable or passive, that means by itself, lifts the brake pad from the brake disc to create a clearance. If the actuator is actively controlled, z. From the control device, which controls the overall braking system is, so the air play adaptive be set. Thus it is possible the air play depends from the driving condition or the driving situation and the brake pad wear or regulate.

The inventive brake system is advantageous characterized by being simple in construction, diagnosable and also adaptive. The brake system according to the invention can be used in both electro-pneumatic and electro-hydraulic Brake systems are used.

Provided An air game has been set, this can be an extra Loss path or a longer response time during braking mean, depending on the operating speed the brake would have a Bremswegverlängerung result. In a full braking to prevent a rear-end collision can cost this crucial meter and lead to the accident. To avoid a Bremswegverlängerung, the invention provides before, before starting the brake application on the brake shoes to apply the brake disc, d. H. to pick up the air play. The Braking system must thus recognize when and if a brake application will be done. This is useful, with rapid accelerator pedal return to control the brake shoes with small braking force or alternatively this via a distance sensor from the foot to the brake pedal to control. Also, the signal or the data from a distance measuring system, which is the distance to the vehicle ahead or obstacle determined, to determine a soon to be initiated braking operation be used. Likewise, the vehicle speed at the Evaluation to be taken into account.

The Air play is advantageously controlled after completion of the braking process, by the actuator the piston or a connected to the brake pad Power transformer moves a corresponding way to to create the air play.

Of the Actuator can advantageously be a solenoid, an electric motor or a Be a linear motor. The actuator can be in a normal wheel brake or an electric motor Parkierbremse be arranged. at the embodiment of a known parking brake with the invention Actuator, the actuator in the simplest case, a spring element, in particular in the form of a compression spring, the brake piston when loosening the parking brake is adjusted to a specific air clearance.

In the solution with a linear motor this acts as a linear magnet within the brake piston, the stator by a non-magnetic sleeve is separated from the brake fluid. In the second solution, a simple solenoid is used. In both solutions, the distance to the foot is preferably measured by a (not shown) distance sensor on the brake pedal before the start of braking and when the threshold value is exceeded, the magnet system is activated or deactivated, so that the clearance is turned off. With appropriate design of the dynamics of the actuators, the signal of the start of braking, z. B. Engage the brake booster to quickly apply the brake pads by the force of the actuator or the spring force. In the linear magnet solution, a displacement sensor can be used for brake lining wear measurement, resulting in the reduction of lining wear sensors.

If after the end of braking, the clearance is controlled on the brake piston side is, remains as a result of friction on the guide pin in the wheel carrier a small residual force on the brake pad, which is a Braking effect generated. Through a simple lifting magnet on the guide pin the floating caliper can also this residual braking effect advantageous turned off.

The Clearance can not be constant during vehicle operation act, z. B. in the rain, the pads must be easy or even before the start of braking after resetting the Accelerated accelerators abut. Also need to go longer journey without braking on a dry road To clean the windows, apply the brake pads at short notice become, what with o. g. Systems also with a defined small Braking force can be done. It is also advantageous if at standstill of the vehicle, z. B. when parking, the clearance is not set becomes.

Advantageous are all the functions described above fully capable of diagnosis, so z. B. by appropriate THZ control the clearance when applying the brake piston to the brake pad, z. B. in vehicle standstill, be tested.

following are the two possible embodiments based on drawings the invention and control concepts explained in more detail.

It demonstrate:

1 A first embodiment of the invention, with a linear motor as an actuator, which is arranged in a wheel brake;

2 a further embodiment of the invention, wherein the actuator is arranged as a spring element in an electric motor-driven parking brake;

3 a third embodiment of the invention, with a lifting magnet as an actuator, which is arranged in the brake piston of a wheel brake;

3a a section of the magnetic yoke with non-magnetic sheet metal;

4 : Further development of a brake system acc. of the 1 to 3 with a Lüftspieleinsteuerung by means of adjustment of the floating caliper of the wheel brake.

The 1 shows an electrical adjustment of the brake piston 49 for generating an air clearance BLS by means of a linear magnet with stator 50 and permanent magnets 51 , The permanent magnets are on the brake piston 49 arranged. In order to achieve a small design, the brake piston is designed pot-shaped towards the working space, wherein the permanent magnets 51 on the cylindrical inside of the pot around the stator 50 are arranged around. The stator 50 is from the pressure chamber through a jacket 54 made of non-magnetic material, which is sealed on the caliper. The movement of the brake piston 49 is preferably by an inductive sensor with coil 48 and Target 48a detected. The electrical connection is via a plug 55 or cable tail. About the spreader 47 is the brake piston 49 to the brake pad 52 couples. After preferably end of braking, the air clearance BLS is generated by the electric piston adjustment, which can be turned off in the described control mode as needed by electrical adjustment of the brake piston again. An application of the brake pads in rain and similar conditions can be done here electrically without hydraulic power. Again, with timely or faster adjustment - as described above - no Pedalwegverlängerung.

The 2 shows the modified one 1 out DE 10 2007 015 809 an electric parking brake with pressure support. With this parking brake, an electric motor sets the spindle with pressure plate after the end of parking braking 56 back through a defined path. The lower half shows the 1 the pre-registration. In the upper half of the picture is the modification drawn in which the pressure plate 56 a flange 56a for supporting the compression spring 57 having. The compression spring 57 supports with its other end on a stop ring 58 from, which is attached to the brake piston. By this construction, it is possible that the brake piston can move freely when pressurized. By return movement - in the figure to the right - the spindle after braking, the air gap BLS can be adjusted via a sensor, wherein the spring force is stronger than the friction force of the seal 29 have to be. In this solution can thus be created by electrically adjusting the spindle before or at the beginning of the braking of the brake pad electrically and canceled the game of air become.

The 3 also shows an electrical adjustment of the brake piston to produce an air clearance BLS. When braking, the brake piston 49 pressurized and exerts a corresponding force by means of the brake pad 52 on the brake disc 59 out. The brake piston slides 49 over the magnet armature 60 with friction element 61 , After completion of the braking occurs at zero pressure, a provision of the brake piston, wherein a residual force through the sealing ring 29 remains. This slides the piston 49 again over the magnet anchor 60 with friction element 61 whose friction force is greater than that of the sealing ring 29 is. Here is the force of the return spring 66 in turn greater than the frictional force of the friction element 61 , so that in the piston return no movement of the armature 60 he follows. After the end of the braking, the magnetic core 62 of the solenoid energized and the armature 60 moves and pulls the brake piston, so that sets a clearance BLS.

By the sliding movement of the brake piston 49 relative to the armature 60 the wear of the lining is automatically compensated. As a result of wear, the brake piston moves forward, in the drawing to the left, and the magnet armature with solenoid 60 remains in position.

As in the previous embodiment, before or at the beginning of the next braking via a control signal of the solenoid 62 switched off again and the brake pad 52 is due to the spring force of the return spring 66 with high dynamics against the brake disc 59 pressed. This ensures that the pedal travel is not adversely affected. Also, the free braking of the brake disc 59 done without pressurization. Furthermore, there is no risk of vapor bubble formation under reduced pressure. The only disadvantage is the small additional power for holding the armature while driving with adjusted clearance BLS and increased residual braking effect when the solenoid fails. The armature movement can be diagnosed by the current change at power up. In this embodiment, two return springs 66 provided, which are arranged symmetrically to the axis of the piston, so there is no tilting of the armature 60 comes.

Below the central axis is an alternative embodiment of the armature 60 shown with storage. In the alternative embodiment, the friction element is designed so that the pressure force is smaller. This is the anchor 60 on the brake piston 49 attached guide pin 65a Gela siege. In addition to the embodiment shown in the upper half of the figure, in the alternative embodiment there are two more springs 69 provided by 90 ° with respect to the compression springs 66 rotated and about the axis of the armature 60 are arranged around staggered. These additional compression springs 69 push against the sliders 68 and 68a , The spring force thus generates a frictional force on the brake piston and on the moving with the brake piston guide pin 65a , By appropriate choice of the spring strength of the springs 69 the friction force can be set exactly. As a result, the spring force to generate the friction force is halved. Since the brake piston is now made of aluminum, a sliding ring 71 made of steel on the brake piston and thus achieved a lower wear. The anchor must be limited in the stroke or air clearance. This is the stop pin 70 connected to the armature and the magnetic core 62 over the stop ring 64a fixed. Preferably, a second arranged by 180 ° pin with stop ring is used. The two compression springs 66 act on the stop ring 64 , The electrical connection is made by appropriate holes in the magnetic circuit to the plug 55 or cable tail.

The 3a shows a section of the magnetic circuit 62 with coil and non-magnetic sheet metal ring 54a , This is a simpler solution than the complete sheath. In addition, there is the advantage that the residual air gap is smaller than the thickness of the welded-in sheet metal ring. This reduces the power required to hold the armature.

The 4 shows a section of the floating saddle bearing with brake holder 33 , Caliper 11a and guide pins 31 , In the guide pin 31 is a magnet armature 32 with bearing pin and with a spreading element 34 provided whose friction is greater than the friction of the two guide pins of the saddle. At the beginning of the braking becomes the coil of the magnet 46 energized and pulls the anchor 32 with caliper 11 at. On the opposite side is due to the reaction force of the brake piston of the caliper 11 over the brake pad 52 pressed on the brake disc and thus generates known the braking effect. After the end of the braking, the magnet becomes 46 shut off, and the reset bolt 35 with compression spring 36 creates a defined clearance BLS ₂ and thus the return of the saddle. By doing that at the start of braking similar 1 Activated by a distance sensor to the brake pedal of the magnet, this clearance BLS ₂ no pedal travel extension result. With appropriate dynamic dimensioning of the actuator, the movement is so fast that the distance sensor is not necessary.

In the foregoing, many feasible solutions are described which allow adaptive control of the air clearance with the aim of braking To keep very low effect, resulting in a high reduction of CO ₂ and fuel consumption. According to the concept of the invention not only brake piston side, but also on the saddle side a clearance with the solutions according to the invention can be selectively adjusted, so that the residual braking effect is almost zero.

11

caliper

31

guide pins

32

armature with bearing pin

33

brake support

34

spreader

35

Reset pin

36

Return spring

37

Brake piston sensor

48

sensor coil

48 °

sensor target

49

brake pistons

50

stator

51

permanent magnets

52

brake lining

53

caliper

54

nonmagnetic shell

54a

non-magnetic sheet metal ring

55

plug

56

printing plate

56a

flange

57

compression spring

58

stop ring

59

brake disc

60

armature

61

friction element

62

magnetic core with coil

63

housing seal

64

stop ring

65

guide pins

65a

alternative guide pins

66

Return spring

67

casing

68

slide

68a

slide

69

compression springs

70

stop pin

71

sliding ring

BLS _i

air game

E ₁

Electric drive as a lifting magnet acc. 1

E ₂

Electric drive as linear motor acc. 3

E ₃

actuator for floating saddle adjustment

EP

electrical parking brake on

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4418701 [0002]
• - DE 19601434 [0002]
• - DE 102007015809 [0023]

Claims (35)

Hydraulically acting brake system with a master brake cylinder, whose at least one working space is connected via at least one hydraulic line to at least one wheel brake or parking brake of the vehicle, characterized in that an actuator at least one brake pad ( 52 ) of a wheel brake to achieve an air clearance (BLS _i ) adjusted. Hydraulically acting brake system according to claim 1, characterized in that the actuator is a spring ( 57 ), which is biased in particular by the actuator, or the actuator is an electric, in particular electromagnetic, drive (E ₁ , E ₂ ). Hydraulically acting brake system according to claim 1 or 2, characterized in that the brake system is an electro-hydraulic Brake system is, in which the master cylinder by means of an electric Drive is adjustable or a pneumatic-hydraulic braking system is, in which the master cylinder is pneumatically adjustable. Hydraulically acting brake system according to one of Claims 1 to 3, characterized in that the actuator acts on a power transmission member to the brake disc. Hydraulically acting brake system according to one of Claims 1 to 4, characterized in that the actuator acts directly on the brake piston of the wheel brake. Hydraulically acting brake system according to claim 5, characterized in that the actuator at least partially within the brake piston ( 49 ) of the wheel brake is arranged. Hydraulically acting brake system according to claim 5 or 6, characterized in that the actuator within the Working space of the piston-cylinder system of the wheel brake arranged is. Hydraulically acting brake system according to claim 6 or 7, characterized in that the brake piston ( 49 ) at its the brake lining ( 52 ) facing away from a recess ( 49a ), in which the actuator rests at least partially. Hydraulically acting brake system according to one of the preceding claims, characterized in that the actuator (E ₁ ) is a linear motor. Hydraulically acting brake system according to claim 9, characterized in that the brake piston ( 49 ) forms the rotor of the linear motor (E ₁ ). Hydraulically acting brake system according to claim 10, characterized in that on the brake piston ( 49 ), in particular in a recess ( 49a ) of the brake piston, permanent magnets ( 51 ) are arranged, which generate an adjusting force for generating an air clearance (BLS) with a stator. Hydraulically acting brake system according to one of claims 7 to 11, characterized in that a separating element ( 54 ) of non-magnetic material, the electrical components, in particular the coils, stator or the magnetic circuit separated from the pressure chamber or the brake fluid. Hydraulically acting brake system according to one of claims 1 to 8, characterized in that the actuator (E ₂ ) is a solenoid, in particular within the brake piston ( 49 ) is arranged. Hydraulically acting brake system according to claim 13, characterized in that the armature ( 60 ) of the lifting magnet via friction, in particular by means of a friction element ( 61 ) with the brake piston ( 49 ) connected is. Hydraulically acting brake system according to one of claims 7 to 14, characterized in that at least one return spring ( 66 ) the brake piston ( 49 ) in the direction of the brake pad ( 52 ) and adjust this when deactivating the actuator in the direction of brake pad. Hydraulically acting brake system according to claim 15, characterized in that the force of the return spring ( 66 ) greater than the frictional force of the piston seal ( 29 ). Hydraulically acting brake system according to claim 15 or 16, characterized in that two additional compression springs ( 69 ) in the magnet armature ( 60 ) whose force is perpendicular to the force of the return springs ( 66 ), wherein the compression springs ( 69 ) with their respective ends in each case two sliders ( 68 . 68a ) against the piston ( 49 ) and guide pins ( 65a ) apply pressure to generate a frictional force. Hydraulically acting brake system according to claim 17, characterized in that the two return springs ( 66 ) and the two additional pressure springs ( 69 ) each about the axis of the armature ( 60 ) are distributed around. Hydraulically acting brake system according to claim 17 or 18, characterized in that Stop pins ( 70 ) on the magnet housing ( 62 ) are arranged, which the hub of the armature ( 60 ) limit. Hydraulically acting brake system according to one of Claims 17 to 19, characterized in that a sheet-metal ring (in particular made of non-magnetic material) ( 54a ), which is in particular welded or soldered, the coil of the actuator from the hydraulic medium sealingly isolated. Hydraulically acting brake system according to claim 20, characterized in that the thickness (s) of the sheet metal ring ( 54a ) greater than the distance (a) from the magnetic yoke to the armature ( 60 ). Hydraulically acting brake system according to one of claims 1 to 4, characterized in that an additional actuator on the caliper ( 11 ) acts. Hydraulically acting brake system according to claim 22, characterized in that the actuator is a linear motor or a solenoid (E ₃ ). Hydraulically acting brake system according to claim 22 or 23, characterized in that the additional actuator in a housing ( 67 ) on the brake caliper carrier ( 33 ) is arranged. Hydraulically acting brake system according to one of the preceding claims, characterized in that a displacement sensor the lifting height or the displacement of the brake piston ( 49 ), the actuator or its movable parts for adjusting the air clearance (BLS _i ) detected. Hydraulically acting brake system according to claim 25, characterized in that by means of the displacement sensor of the brake pad wear can be determined is. Hydraulically acting brake system according to claim 1, characterized in that the brake piston via at least one spring element ( 57 ) is coupled to the drive of an electric parking brake (EP), wherein by resetting the drive of the parking brake, the spring element ( 57 ) A force for lifting the brake pad from the brake disc on the brake piston ( 49 ), wherein the introduced spring force is greater than the frictional force of the brake piston seal ( 29 ). Hydraulically acting brake system according to one of the preceding claims, characterized in that a controller adjusts or adjusts the clearance (BLS _i ) as a function of the driving situation. Hydraulically acting brake system according to claim 28, characterized in that the control in the rain and / or wet lane no clearance in the wheel brakes generated. Hydraulically acting brake system according to claim 28 or 29, characterized in that when the road is dry after a certain driving time and / or driving distance the clearance generation is interrupted, and for a predeterminable time, the brake pads the wheel brakes against the brake discs to achieve a braking effect be pressurized. Hydraulically acting brake system according to one of Claims 28 to 30, characterized in that at normal Ride without operation of the brake by the person driving a clearance is set by the controller. Method using a hydraulically acting Brake system according to one of the preceding claims, characterized characterized in that the clearance (BLS) in the individual Wheel brakes is canceled as soon as the braking system based on the driving situation recognizes that a braking process is imminent. Method according to claim 32, characterized in that that the actuators are designed so that they the brake pad quickly apply the respective wheel brake at the start of braking. A method according to claim 32 or 33, characterized that on the basis of the movement of the gas pedal, in particular its speed, the speed of the brake-actuating foot, the distance of the brake pedal actuating foot relative to the brake pedal and / or the signal of a distance warning system the braking system is the impending initiation of a braking process recognizes. Method according to one of claims 32 to 34, characterized in that at least one distance sensor ( 7 ) determines the distance of the foot to the brake pedal in at least one, preferably in three directions.