DE19836139A1 - Brake lift simulator - Google Patents

Abstract

The arrangement (92) includes a first butt (96) and a second butt (108) which is adjustable along with the first butt in a second distance, after the first butt has been shifted a first distance. A first spring (106) presses the first butt away from the second butt. A second spring (116) presses the second butt towards the first butt. An elastic component (122, 124) is arranged in a contact position between the first butt and the second butt. The arrangement includes a first butt adjustable in response to a pressure (PMC) from the main cylinder (12) in a first (G1) and a second distance (G2), and a second butt which is adjustable along with the first butt in the second distance, after the first butt has been shifted the first distance. A first spring presses the first butt away from the second butt. A second spring presses the second butt towards the first butt. An elastic component is arranged in a contact position between the first butt and the second butt.

Description

On the disclosure content of the on August 8, 1997 filed Japanese Patent Application No. HEI 9-215011 finally the description, the claims, the together version and the drawing is hereby fully described pulled.

The invention relates generally to a brake hub mulator and in particular a brake stroke simulator with which itself in the case of an electronically controlled brake device tion of a motor vehicle has a good brake actuation feeling can be preserved.

An electronically controlled vehicle brake device with a brake stroke simulator, for example, in the Japanese Patent Application Laid-Open No. HEI 6-211124 disclosed. The braking stroke is at this braking device Simulator in connection with a master cylinder, which in the An speak to a brake pedal operator a correspond corresponding master cylinder pressure generated.

This conventional braking device has a high pressure source regardless of whether a brake pedal actuating force, continuously a certain Brake fluid pressure generated. When the brake is actuated dals the connection between the master cylinder and the Wheel cylinders interrupted and the wheel cylinder pressure below Using the high pressure source as a brake fluid regulates the pressure source, provided the braking system is operating normally tet. The brake fluid flows from the master cylinder into the Brake stroke simulator.

The braking device described in the above provided brake stroke simulator has a piston that is shifted under the effect of the master cylinder pressure,  as well as a large number of disc springs that hold the piston in an egg Press ne direction, the direction of the one under the effect the force caused by the master cylinder pressure is. The disc springs are arranged one behind the other. Becomes the piston under the effect of the master cylinder pressure pushed, the disc springs generate a reaction force. The The displacement or the stroke of the piston increases with increasing Pedal stroke too. The reaction generated by the disc springs force in turn increases with increasing piston stroke. Therefore, the reaction generated by the disc springs increases force with increasing pedal stroke.

The master cylinder pressure increases when the through the Disc springs generated reaction force increases. With a Rise in master cylinder pressure also rises to Brake pedal transmitted pedal reaction force. The brake stroke simulator therefore enables a stronger actuation brake pedal an increase in pedal response force.

With a normal manual braking device (the hereinafter referred to as "normal braking device" the master cylinder pressure is sent directly to the Radzy more relaxed. This device is characterized by a non-linear relationship between pedal reaction force and the pedal stroke. If the pedal stroke is particularly small, then the pedal reaction force changes with respect to the Pedal stroke relatively weak. If the pedal stroke is large, then the pedal reaction force changes with a change of the pedal stroke relatively strong.

Such a non-linear characteristic of the pedal reactions on force in relation to the pedal stroke, which is similar to that which is obtained with normal braking devices can be achieved by as described above brake stroke simulator use a stack of disc springs det. Although in the conventional brake device  Connection between the master cylinder and the wheel cylinders is interrupted, the conventional braking device create a brake pedal actuation feeling that one is similar to that obtained with normal braking devices becomes.

However, the characteristic or characteristic curve changes of the conventional brake stroke simulator with a change in Arrangement state of the disc springs. In the production of Brake stroke simulators make it difficult to continuously keep the to get the same arrangement state of the disc springs. Forth Conventional brake stroke simulators are therefore subject to manufacture deviations due to their characteristics.

The object of the invention is therefore a Bremshubsimu lator, with which it is possible to manufacture contingent deviations under the characteristics of individual brakes to reduce stroke simulators.

This task is accomplished by a brake stroke simulator the features of claim 1 or 5 or by Braking method according to the features of claim 11 or 13 solved. Advantageous further developments are Ge subject of the respective subclaims.

A first aspect of the invention provides a brake hub mulator before, which has: a first piston, which in the An speak to a master cylinder pressure is slidable; egg NEN second piston that ver together with the first piston is slidable when the stroke of the first piston is equal to or a specified stroke is larger; a first spring that the first piston and the second piston in the stroke direction Pressure applied; a second spring that the second col pushes towards the first piston; as well as an elastic Component that is in a contact position between the first Piston and the second piston is arranged.  

According to the first aspect of the invention, the Be drawing between the pedal stroke and the pedal reaction force on the spring force of a variety of springs.

The first piston, in particular, has an increase of the master cylinder pressure shifted. Up to a certain one The stroke of the first piston is under an elastic deformation tion of the first spring only the first piston moved; of the second piston is essentially not moved. In the case of the brake stroke simulator according to the first aspect of FIG Determine invention until reaching the certain stroke the first piston, d. H. until the first piston the second Piston contacted, only the characteristics of the first spring Relationship between pedal stroke and pedal response force. After the first piston contacts the second The piston increasingly undergoes elastic deformation elastic component. After a sufficient elastic Deformation of the elastic component is a state of being enough in which the relationship between the pedal stroke and the Pedal reaction force from the characteristics of the second spring be be true. During a period between the contact of the first piston with the second piston and the row appropriate elastic deformation of the elastic component the pedal reaction force characteristic changes continuously from one characteristic curve determined by the characteristics of the first spring a characteristic determined by the characteristics of the second spring line. In the area where the stroke of the first piston is larger than the specified stroke, the second piston moved together with the first piston, the second Spring is deformed elastically; the size of the elastic Deformation of the first spring remains constant. In this To is the relationship between the pedal stroke and the Pe dal reaction force essentially only from the spring constant te the second spring determined.

In the case of the brake stroke simulator according to the invention the relationship between the pedal stroke and the  Pedal reaction force with relatively small pedal strokes of that with relatively large pedal strokes. This on the way described above achieved non-linear characteristics line with a normal braking device targeted pedal reaction force characteristic to be approximated in which the characteristics of the first spring and the characteristics of the second spring can be specified appropriately. Therefore, with the brake stroke simulator according to the invention a stable brake pedal actuation feeling can be achieved, d. H. a brake pedal feeling of activity that is similar to that of the normal braking device is obtained, with strong Ab deviations under the characteristics of individual products redu are adorned.

The brake stroke simulator according to the first Aspect may further include a housing in which the first Piston is inserted, as well as one between the first piston ben and the housing provided sleeve-like seal a check valve type designed to prevent the master cylinder pressure escapes. This configuration bears effectively contributes to a hysteresis in the characteristic curve of the Pe to reduce dal reaction force.

When the pedal stroke increases, the first piston becomes pushed the second piston. At this stage, the pe dalreaction force a value corresponding to the sum of the generated by the first spring or by the second spring Pressure force and the sliding resistance of the first piston ent speaks. When the pedal stroke decreases, the first piston pushed away from the second piston. The pedal crack force a value corresponding to a force that by the sliding resistance of the first piston of that generated by the first spring or the second spring Compressive force is subtracted. When it comes to the first piston around a seal to seal the gap between which he Most pistons and the housing is arranged, the sliding resistance of the first piston strongly from the sliding resistance  between the seal and the housing. If the Seal during an increase in pedal stroke and during a decrease in the pedal stroke the same sliding resistance has the pedal reaction force accordingly With an increase in the pedal stroke larger and during one Decrease in pedal stroke less.

In the configuration according to which the first piston with the check type cuff type seal valve is provided, the seal during an ab taking the pedal stroke, d. H. during a decrease in Master cylinder pressure, elastically deformed radially inwards, d. H. so that the diameter of the seal is reduced. If the cuff-like seal of the type one Check valve elastically deformed radially inwards, the sliding resistance of the first piston decreases. Therefore with the brake stroke simulator according to this embodiment After a decrease in the pedal stroke, a pedal reaction force get that essentially from that through the first spring or second spring pressure force depends. There during a decrease in pedal stroke thus a relatively large pedal reactive force is achieved, the sliding resistance the hysteresis resulting from the seal was in the characteristic curve the pedal reaction force is reduced.

A second aspect provides a brake stroke simulator, which comprises: a first piston responsive to a master cylinder pressure is displaceable; a second Piston ver in response to master cylinder pressure is slidable; at least one coil spring that he push the piston and the second piston in one direction, that of the direction of under the action of the master cylinder pressure generated force is opposite; and one Piston stop opposite the stroke of the first piston the stroke of the second piston is reduced. The at least one ne coil spring can be a coil spring that the pressurize the first piston and the second piston  strikes. The master cylinder pressure that the first piston up moves to the end of its stroke differs from that Master cylinder pressure that the second piston up to its End of stroke moves.

According to the second aspect, the first piston and the second piston be pressurized by a coil spring hits. The first and second pistons are both together men shifted when the master cylinder pressure is lower as a certain pressure. The relationship between the pedal stroke and the pedal reaction force from the sum the pressure-receiving surface of the first piston and the pressure-receiving surface of the second piston and the Characteristics of the coil spring determined.

If the master cylinder pressure is greater than that te pressure, there will be a further displacement of the first piston prevented by the piston stop. Therefore, in this Pressure range only the second piston corresponding to the same weight between that under the effect of the master cylinder pressure force and the pressure force caused by the pressure Coil spring moved. The relationship between between the pedal stroke and the pedal reaction force from the pressure-receiving surface of the second piston and the Merk paint the coil spring determined.

According to the second aspect, that at re Relatively small pedal strokes given relationship between the Pedal stroke and pedal reaction force from the at relative large pedal strokes given relationship between the pedal stroke and pedal reaction force. This be on the above written non-linear characteristic can pedal reactions achieved with a normal braking device force curve can be approximated by taking up the pressure menden surfaces of the first and second pistons and the Merk paint the at least one coil spring on which he and the second piston applies pressure, suitable  can be set. Therefore, with the invention Brake stroke simulator according to the second aspect is a stable one Brake pedal actuation feeling is obtained, d. H. a Brake pedal actuation feeling similar to that that is obtained with the normal braking device, whereby large deviations under the characteristics of individual products are reduced.

The brake stroke simulator according to the invention aspect can also have a piston stop which a smaller stroke than the stroke of the second piston of the first piston; the at least one screw spring can be a coil spring that the first piston and pressurize the second piston with each other.

The foregoing and other features and advantages of Invention follow from the description below Zugter embodiments, in the on the attached drawing is referred to, the same reference numerals to represent the same or corresponding components be applied. It shows:

Fig. 1 is a schematic view of an electronically controlled brake device, for which various forms of execution of the brake stroke simulator according to the invention are used

Fig. 2 is a sectional view of the brake stroke simulator according to the invention in a first embodiment;

Fig. 3 is a diagram showing the obtained with a conventional, normal brake device relationship between the master cylinder pressure P _MC and the pedal stroke S;

Fig. 4 is a diagram showing the relationship obtained with a conventional brake stroke simulator between the master cylinder pressure P _MC and the pedal stroke S;

Fig. 5 is a diagram showing the relationship obtained by the brake stroke simulator in the first embodiment between the master cylinder pressure P _MC and the pedal stroke S;

Fig. 6 is a sectional view of the brake stroke simulator according to the invention in a second embodiment;

Fig. 7 is a sectional view of the brake stroke simulator according to the invention in a third embodiment; and

Fig. 8 is a sectional view of the brake stroke simulator according to the invention in a fourth embodiment.

With reference to the accompanying drawing preferred embodiments of the invention below described in detail.

Fig. 1 shows a schematic structure of an electro nically controlled braking device, for which different embodiments of the brake stroke simulator according to the invention are used. The electronically controlled Bremsvorrich device includes a brake pedal 10 which is connected to a brake booster 11 . The Bremskraftver stronger 11 is attached to a master cylinder 12 . The brake booster 11 increases the brake operating force applied to the brake pedal 10 and transmits the increased force to the master cylinder 12 . The master cylinder 12 it generates a master cylinder pressure P _MC , which is in a certain gain ratio to the brake actuation force.

A regulator 14 is attached to the master cylinder 12 . Above the master cylinder 12 and the controller 14 , a compensation container 16 is arranged. The expansion tank 16 contains brake fluid. The master cylinder 12 communicates with the surge tank 16 only when the brake pedal 10 is not actuated.

The braking device has a pump 18 . At a suction opening of the pump 18 is in communication with the expansion tank 16 . The pump 18 sucks brake fluid from the equalizing reservoir 16 and ejects it from its outlet opening. The discharge opening of the pump 18 is connected via a check valve 20 with a memory 22 . The reservoir 22 stores the fluid expelled by the pump 18 with a reservoir pressure P _ACC . The pump 18 is operated in such a way that the accumulator pressure P _{ACC is kept} in the range between an upper limit value and a lower limit value in this regard.

The memory 22 is connected to the controller 14 . The controller 14 is connected to the expansion tank 16 . Using the accumulator 22 as a high pressure source and the expansion tank 16 as a low pressure source, the regulator 14 generates a regulator pressure P _RE which is equal to the master cylinder pressure P _MC .

A regulator pressure line 24 is connected to the regulator 14 . The regulator pressure line 24 is provided with a fluid pressure sensor 26 which outputs an electrical signal pRE corresponding to the regulator pressure P _RE . The regulator pressure line 24 is connected to an amplifier linear control valve 28 and a check valve 30 in connection. A control fluid pressure line 32 is connected to the United stronger linear control valve 28 and the check valve 30 . The booster linear control valve 28 is a control valve that a brake fluid flow from the regulator pressure line 24 into the control fluid pressure line 32 in an amount that is substantially proportional to a drive signal applied to the valve 28 . The Rückschlagven valve 30 allows fluid flow only in the direction of the control fluid pressure line 32 in the regulator pressure line 24 .

The control fluid pressure line 32 is provided with a fluid pressure sensor 34 which outputs an electrical signal pR corresponding to the pressure in the control fluid pressure line 32 . The control fluid pressure line 32 is connected to an additional tank 40 via a pressure reducing linear control valve 36 and a check valve 38 . The Druckmin der-Linearsteuerventil 36 is a control valve that allows a brake fluid flow from the control fluid pressure line 32 to the additional container 40 in an amount that is substantially proportional to an applied to the valve 36 Ansteuersi signal. The check valve 38 allows a brake fluid flow only in the direction from the additional container 40 into the control fluid pressure line 32 . The additional container 40 can hold a certain amount of brake fluid.

The control fluid pressure line 32 is connected via an electromagnetic holding valve 42 and a check valve 44 to a rear fluid pressure line 46 . The electromagnetic holding valve 42 is an electromagnetic 2-way valve which is open in the normal state and is only closed when a control signal is applied. The check valve 44 allows fluid flow only in the direction from the rear fluid pressure line 46 into the control fluid pressure line 32 .

The rear fluid pressure line 46 is connected via a proportional valve 48 to a rear left wheel cylinder 50 and a rear right wheel cylinder 52 . The rear fluid pressure line 46 is also via an electromagnetic pressure reducing valve 54 with a return line 56 in connection. The proportional valve 48 feeds the fluid pressure in the rear fluid pressure line 46 directly to the wheel cylinders 50 , 52 when the fluid pressure is below a certain level. When the fluid pressure in the rear fluid pressure line 46 is above the certain level, the proportional valve 48 decreases the fluid pressure in a certain ratio and supplies the reduced pressure to the wheel cylinders 50 , 52 . The electromagnetic pressure reducing valve 54 is an electromagnetic 2-way valve that normally remains closed and is only opened when a control signal is applied. The return line 56 is connected to the above-described reservoir 16 in connection.

The control fluid pressure line 32 is connected to a front fluid pressure line 60 via a pressure build-up shutoff valve 58 . The pressure build-up shut-off valve 58 is an electromagnetic 2-way valve which is closed in the normal state and only opens when a control signal is applied. The front fluid pressure line 60 is provided with a fluid pressure sensor 62 which outputs an output signal pF corresponding to the pressure in the line 60 .

The front fluid pressure line 60 is connected via an elec tromagnetic holding valve 64 and a check valve 66 to a front left fluid pressure line 68 . The front fluid pressure line 60 is also via an electromagnetic holding valve 70 and a check valve 72 with a front right fluid pressure line 74 in connection. The electromagnetic holding valves 64 , 70 are electromagnetic 2-way valves that remain open in the normal state and are only closed when a control signal is applied. The check valves 66 , 72 allow fluid flow only in the direction from the front left fluid pressure line 68 or the front right fluid pressure line 74 to the front fluid pressure line 60 .

The front left fluid pressure line 68 and the front right fluid pressure line 74 are connected to the front left and front right wheel cylinders 76 and 78, respectively. The front left fluid pressure line 68 and the front right fluid pressure line 74 are also via an elec tromagnetic pressure reducing valve 80 and 82 with the return line 56 in connection. The electromagnetic pressure reducing valves 80 , 82 are electromagnetic 2-way valves, which remain closed in the normal state and are only opened when a control signal is applied.

A master pressure line 84 communicates with the master cylinder 12 . The main pressure line 84 is provided with a main pressure sensor 86 which outputs a master cylinder pressure P _MC corresponding electrical signal pMC. The main pressure line 84 is connected via a main shut-off valve 88 or 90 to the front left fluid pressure line 68 or the front right fluid pressure line 74 . The main shut-off valves 88 , 90 are electromagnetic 2-way valves which remain open in the normal state and are only closed when a control signal is applied. The main pressure line 84 is also connected to a brake stroke simulator 92 . The brake stroke simulator 92 is connected to the return line 56 and the main pressure line 84 .

Fig. 2 shows a sectional view of the brake stroke simulator 92 according to the invention. The brake stroke simulator 92 has a housing 94 which contains a first piston 96 . The first piston 96 partially defines a main pressure chamber 98 in the housing 94 . The main pressure chamber 98 is connected to the main pressure line 84 .

The first piston 96 is provided with an O-ring 100 and a support ring 102 . The gap between the first Kol ben 96 and the housing 94 is sealed by the O-ring 100 abge. The first piston 96 also has a Rohrab section 104 . A first spring 106 is arranged in the tube section 104 . The brake stroke simulator 92 also has a second piston 108 , which in turn has a Paßab section 110 and a flange section 111 . The passport section 110 is slidably inserted in the pipe section 104 of the first piston 96 .

Fig. 2 shows the first piston 96 and the second piston 108 ben in their initial positions. The brake stroke simulator 92 is constructed so that when the first piston 96 and the second piston 108 are in their initial positions, between the end face of the first piston 96 and the flange portion 111 of the second piston 108, a position G1 of a certain size was formed is as shown in Fig. 2.

The first spring 106 abuts the end face of the Paßab section 110 of the second piston 108 . The first spring 106 pushes the first piston 96 and the second piston 108 in opposite directions. When a comparable with the pressing force of the first spring 106 master cylinder pressure P _MC is guided in the main pressure chamber 98, the first piston 106 is pushed 96 under elastic deformation of the first of the Fe to the second piston 108 down. When the stroke of the first piston 96 becomes as large as the gap size G1, the first piston 96 contacts the second piston 108 . Subsequently, the force which is applied to the piston 96 by the master cylinder pressure P _MC guided into the main pressure chamber 98 is transmitted to the second piston 108 .

A return chamber 112 is also formed in the housing 94 . A plug 114 closes the return chamber 112 . The return chamber 112 is connected to the return line 56 at a point (not shown in FIG. 2) in the return chamber 112 . A second spring 116 is arranged between the second piston 108 and the sealing plug 114 . The second spring 116 generates a force that pushes the second piston 108 and the plug 114 in opposite directions. When ei ne force is transmitted from the first piston 96 to the second piston 108 , the second piston 108 is pushed to the plug 114 out.

The second piston 108 and the sealing plug 114 each have a stop 117 and 118, respectively. The brake stroke simulator 92 is constructed in such a way that a distance G2 of a certain size is formed between the stop 117 and the stop 118 when the second piston 108 is in its initial position. The second piston 108 can accordingly be pushed towards the sealing plug 114 until the stop 117 contacts the stop 118 . The first piston 96 can consequently be pushed out of its starting position by the defined distance G1 + G2 to the plug 114 .

The capacity of the main pressure chamber 98 varies with the stroke of the first piston 96 . The capacity of the main pressure chamber 98 increases with a displacement of the first piston 96 by the distance G1 + G2 from its initial position by a volume of πoD1o (G1 + G2), where D1 represents the diameter of the first piston 96 . The Bremshubsi mulator 92 is thus able to increase a maximum amount of brake fluid, which can be expressed by πoD1o (G1 + G2), when the master cylinder pressure P _{MC is} supplied from the main pressure line 84 .

The brake device shown in FIG. 1 performs brake fluid pressure control when the vehicle operator operates the brake, provided the system is operating normally. The brake fluid pressure control is carried out by closing the main shut-off valves 88 , 90 (ON state) and opening the pressure build-up shut-off valve 58 (ON state) and controlling the booster linear control valve 28 and the pressure reducing linear control valve 36 appropriately.

The brake fluid pressure control interrupts the connection between the wheel cylinder 76 or 78 of the left or right front wheel FL or FR and the master cylinder 12 and a connection between the wheel cylinder 76 or 78 of the left or right front wheel FL or FR and the Control fluid pressure line 32 set up; in contrast, the connection between the wheel cylinder 50 and 52 on the left or right rear wheel RL or RR and the control fluid pressure line 32 is maintained. By the brake fluid pressure control, the wheel cylinder pressure P _WC can thus be controlled in all wheel cylinders using the controller 14 as a fluid pressure source.

The regulator 14 generates the regulator pressure P _RE , which is the same as the master cylinder pressure P _MC , as described above. By a suitable control of the United-linear control valve 28 and the pressure-reducing linear control valve 36 , any fluid pressure that is lower or substantially as large as the master cylinder pressure P _MC can therefore be applied to the wheel cylinders 50 , 52 on the left or right front derrad FL, FR and the wheel cylinders 76 , 78 on the left and right rear wheel RL, RR are performed.

If an error occurs that complicates or hinders the execution of the brake fluid pressure control, the brake device shown in FIG. 1 prevents the brake fluid pressure control. In this case, after the initiation of the brake fluid pressure control, the main cut valves 88 , 90 are kept in the open state (OFF state), while the pressure build-up cut valve 58 is kept in the closed state (OFF state).

When the master valves 88 , 90 and the pressure build-up valve 58 are kept in the OFF state, there is a state in which the wheel cylinders 76 , 78 on the left and right front wheels FL and FR are in communication with the master cylinder 12 and the wheel cylinders 50 , 52 on the left and right rear wheels RL and RR are connected to the controller 14 via the amplifier linear control valve 28 . In this state, the master cylinder pressure P _MC can be guided into the wheel cylinders 76 , 78 on the left and right front wheels FL and FR, while a pressure can be guided in the wheel cylinders 50 , 52 on the left and right rear wheels RL and RR , which corresponds to the regulator pressure P _RE minus the pressure for opening the amplifier linear control valve 28 . With the braking device shown in FIG. 1, a sufficiently high braking force can thus be created even if a fault occurs in the system.

During the brake fluid pressure control, the brake fluid amount in the master cylinder 12 is not guided to the wheel cylinders 76 , 78 , as described above. The brake pedal 10 can be operated because brake fluid flows from the master cylinder 12 . If, however, no brake fluid can flow from the master cylinder 12 during the brake fluid pressure control, no brake pedal operation feeling can be created which is equivalent to the brake pedal operation feeling obtained with a normal brake device.

In the brake device shown in FIG. 1, the brake stroke simulator 92 can absorb a certain amount of the brake fluid supplied from the main pressure line 84 . Therefore, when the brake fluid pressure control is performed in the brake device shown in FIG. 1, brake fluid is discharged and received between the master cylinder 12 and the brake stroke simulator 92 . In the Bremsvorrich device shown in Fig. 1, the master cylinder 12 can therefore be operated appropriately during the brake fluid pressure control.

In a brake device that uses a brake stroke simulator to ensure a brake stroke, the relationship between the pedal stroke and the pedal reaction force is determined by the characteristic of the brake stroke simulator. The brake stroke simulator 92 in this embodiment is so simple that deviations under the characteristics of individual products are unlikely. Another feature of the brake stroke simulator 92 is that the brake stroke simulator 92 is capable of establishing a relationship between the pedal stroke and the pedal reaction force that is similar to that of a normal brake device. The characteristics of the brake stroke simulator 92 in this out will now be explained with reference to Fig. 2 and Figs. 3 to 5 guide die.

Fig. 3 shows the relationship between the master cylinder pressure P _MC and the pedal stroke S, which is achieved with a normal braking device, that is, a device that controls the wheel cylinder pressure P _WC using a master cylinder as a fluid pressure source. The brake pedal produces a reaction force corresponding to the master cylinder pressure P _MC . Therefore, the relationship shown in FIG. 3 can be regarded as the relationship between the pedal reaction force and the pedal stroke obtained with a normal brake device.

In the normal brake device, the amount of brake fluid Q _MC flowing out of the master cylinder is always proportional to the pedal stroke S. During a period from the start of a brake operation until the brake fluid pressure rises to a certain level, the brake fluid flowing to the master cylinder becomes partial for the Expansion of brake hoses and the like consumed. Therefore, in the normal braking device, the gradient of the change in the master cylinder pressure P _MC with respect to the pedal stroke S, ie the differential dP _MC / dS of the master cylinder pressure P _MC with respect to the pedal stroke S, is relatively small in the area of small pedal strokes and relatively large in the area of large pedal strokes as shown in FIG. 3.

Fig. 4 shows the relationship between the master cylinder pressure P _MC and the pedal stroke S, which is achieved with the conventional brake stroke simulator, which has only one spring stage. Such a brake stroke simulator has a piston which is displaced under the action of the master cylinder pressure P _MC and a spring which pushes the piston into its initial position.

The amount of brake fluid Q _MC flowing out of the master cylinder is proportional to the pedal stroke S as described above. In the case of a brake device with a brake stroke simulator, the total amount of brake fluid Q _{MC flows} from the master cylinder into the brake stroke simulator. Therefore, the piston provided in the brake stroke simulator is shifted ben by a distance proportional to the amount of brake fluid Q _MC flowing out of the master cylinder, ie proportional to the pedal stroke S.

In the conventional brake stroke simulator described above, a spring that pressurizes the piston undergoes an elastic deformation that is as large as the displacement of the piston. The spring produces a reaction force corresponding to the size of the elastic deformation. In the brake stroke simulator described above, the piston therefore experiences a reaction force proportional to the pedal stroke S until the piston reaches the end of its stroke. In the fluid pressure line from the master cylinder to the brake stroke simulator, the master cylinder pressure P _{MC is} proportional to the reaction force transmitted to the piston.

The brake stroke simulator described above is thus able to adjust the master cylinder pressure P _MC with respect to changes in the pedal stroke S in a range in which the piston has not yet reached the stroke end, ie in a range in which the pedal stroke is relatively small, linearly change as shown in FIG. 4. In the normal Bremsvor direction, however, the master cylinder pressure P _MC has a non-linear tendency to change with respect to changes in the pedal stroke S, as shown in Fig. 3. Therefore, it has been found difficult to reproduce the relationship between the master cylinder pressure P _MC and the pedal stroke S obtained with a normal brake device with the conventional brake stroke simulator in which only one spring stage is used.

Fig. 5 shows the relationship between the master cylinder pressure P _MC and the pedal stroke S, which is achieved with a Bremsvorrich device in which the brake stroke simulator 92 is used in this embodiment. In an area in which the master cylinder pressure P _MC led into the master pressure chamber 98 is small, only the first piston 96 is displaced in the brake stroke simulator 92 , while the second piston 108 remains in its initial position. The compressive force of the first spring 106 is transmitted to the first piston 96 as a reaction force. In this case, depending on the characteristics of the first spring 106 , ie the spring constant, the spring length and the like. Between the master cylinder pressure P _MC and the pedal stroke S, a linear relationship is achieved.

In a region in which the run in the main pressure chamber 98 master cylinder pressure P _MC is so large that the first piston is brought into contact with the second piston 108. 96, the brake stroke simulator 92, the second piston will together 108 moved with the first piston 96 . The compressive force of the second spring 116 is transmitted to the first piston 96 as a reaction force. In this case, depending on the characteristics of the second spring 116 , ie the spring constant, the spring length and the like. Between the master cylinder pressure P _MC and the pedal stroke S, a linear relationship is achieved.

With the brake stroke simulator 92 in this embodiment, a relationship between the master cylinder pressure P _MC and the pedal stroke S can thus be obtained, which is rich in a region in which the master cylinder pressure P _{MC is} relatively small, features of the first spring 106 and in a region rich, in which the master cylinder pressure P _{MC is} relatively large, depends on the second spring 116 . With the brake stroke simulator 92 , therefore, a non-linear relationship between the master cylinder pressure P _MC and the pedal stroke S can be obtained, which is similar to the relationship obtained with the normal brake device as shown in FIG. 5.

The characteristic of the brake stroke simulator 92 in this embodiment is determined by the features of the first spring 106 and the features of the second spring 116 , as described above. Deviations of these features can be relatively easily reduced to small loading area during the manufacture of the first spring 106 and the second spring 116 . Therefore, the brake stroke simulator 92 ensures in this embodiment a constant quality without great manufacturing-related deviations under the characteristics of individual brake stroke simulators.

A second embodiment of the invention will now be described with reference to FIG. 6. Fig. 6 shows a sectional view ei ne brake stroke simulator 120 according to the second embodiment. The comparable with those components in Fig. 2 components are designated in Fig. 6 with the same reference numerals and will not be explained.

The brake stroke simulator 120 in the second embodiment has elastic components 122 , 124 , 126 , 128 . The ela-elastic components 122 , 124 are arranged on the flange portion 111 of the second piston 108 . The elastic components 122 , 124 contact the end face of the first piston 96 when the first piston 96 is pushed beyond a certain distance to the second piston 108 . The ela-elastic components 126 , 128 are arranged at the stop 118 of the sealing plug 114 and contact the stop 117 of the second piston 108 when the second piston 108 is displaced over a certain distance to the sealing plug 114 .

In the case of the brake stroke simulator 120, until such time as the first piston 96 comes into contact with the elastic members 122, 124, only the reaction force of the first spring 106 (see Fig. 2) transmitted to the first piston 96. At this stage, the relationship between the pedal stroke S and the pedal reaction force is essentially determined only by the characteristics of the first spring 106 .

After the first piston 96 has come into contact with the elastic components 122 , 124 , the reaction force of the first spring 106 and the reaction force of the second spring 116 are transmitted to the first piston 96 until the second piston 108 begins to move . At this stage, the relationship between the pedal stroke S and the pedal reaction force is largely determined by the characteristics of the first spring 106 and the spring constant of the elastic members 122 , 124 .

The spring constant of the elastic components 122 , 124 increases with their elastic deformation. The spring constant of the elastic components 122 , 124 therefore increases with increasing displacement of the first piston 96 . If the spring constant of the elastic members 122 , 124 is relatively small, the relationship between the pedal stroke S and the pedal reaction force depends essentially on the characteristics of the first spring 106 . When the spring constant of the elastic members 122 , 124 increases, the spring constant of the elastic members 122 , 124 exerts a greater influence on the relationship between the pedal stroke S and the pedal reaction force. Therefore, the relationship between the pedal stroke S and the pedal reaction force in a brake device in which the brake stroke simulator 120 is used after the first piston 96 comes into contact with the elastic members 122 , 124 changes from the relationship that is substantially different from that Features of the first spring 106 be determined gradually and steadily to the relationship, which is relatively strongly dependent on the spring constant of the elastic construction parts 122 , 124 .

When the elastic deformation of the elastic components 122 , 124 has progressed sufficiently so that the compressive force transmitted from the elastic components 122 , 124 and the first spring 106 to the second piston 108 becomes sufficiently large, the displacement of the second piston begins 108 . At this stage, the relationship between the pedal stroke S and the pedal reaction force is largely determined by the characteristics of the second spring 116 and the spring constant of the elastic members 122 , 124 .

In the above-described state, the influence of the spring constant of the elastic members 122 , 124 on the relationship between the pedal stroke S and the pedal reaction force decreases when a change in the amount of elastic deformation of the elastic members 122 , 124 becomes more difficult, ie when the spring constant of the elastic members 122 , 124 increases. With increasing displacement of the second piston 108 , the relationship between the pedal stroke S and the pedal reaction force from the relationship, which is essentially determined by the characteristics of the second spring 116 and the spring constant of the elastic members 122 , 124 , changes gradually and continuously the relationship that is essentially determined by the characteristics of the second spring 116 .

When the second piston 108 is displaced sufficiently, it comes into contact with the elastic components 126 , 128 . After the second piston 108 contacts the elastic members 126 , 128 , the relationship between the pedal stroke S and the pedal reaction force is primarily influenced by the characteristics of the second spring 116 and the spring constant of the elastic members 126 , 128 .

The spring constant of the elastic components 126 , 128 increases with increasing elastic deformation of the elastic components 126 , 128 . If the spring constant of the elastic members 126 , 128 is relatively small, the relationship between the pedal stroke S and the pedal reaction force depends essentially on the characteristics of the second spring 116 . Therefore, the relationship between the pedal stroke S and the pedal reaction force immediately after the second piston 108 comes into contact with the elastic members 126 , 128 is primarily based on the characteristics of the second spring 116 . With increasing displacement of the second piston 108 , the relationship between the pedal stroke S and the pedal reaction force gradually and steadily changes to the relationship that exists after the second piston 108 has reached its stroke end.

The brake stroke simulator 120 in this embodiment thus enables a gradual and steady change in the relationship between the pedal stroke S and the pedal reaction force from the relationship determined by the characteristics of the first spring 106 to the relationship determined by the characteristics of the second spring 116 is determined, and from the relationship determined by the characteristics of the second spring 116 to the relationship existing after the second piston 108 has reached its stroke end. With the brake stroke simulator 120 , therefore, a good braking feel can be created without a large change in the pedal reaction force change amount.

A third embodiment of the invention will now be described with reference to FIG. 7. Fig. 7 ei ne-sectional view of the brake stroke simulator 130 according to the third embodiment. The comparable with those components in Fig. 2 components are designated in Fig. 7 with the same reference numerals and will not be explained.

The brake stroke simulator 130 in this embodiment has a cuff-like seal 132 of the check valve type, which is arranged on the first piston 96 . The seal 132 is made of an elastic material. When the master cylinder pressure P _MC in the master pressure chamber 98 increases, the seal 132 is elastically deformed radially outward, thereby improving the seal between the first piston 96 and the housing 94 .

In a braking device in which the brake stroke simulator 130 is used, the brake fluid flows into the main pressure chamber 98 depending on the pedal stroke. When the brake fluid flows into the main pressure chamber 98 , the first piston 96 is pushed toward the plug 114 , the seal 132 being in close contact with the housing 94 . At this stage, the master cylinder pressure P _MC prevails in the master pressure chamber 98 in accordance with the sum of the compressive force of the first spring 106 or the second spring 116 , which pressurizes the first piston 96 , and the sliding resistance between the seal 132 and the housing 94 .

When the pedal stroke S decreases in the case of the brake device in which the brake stroke simulator 130 is used, the brake fluid flows from the master pressure chamber 98 to the master cylinder. With the outflow of the brake fluid from the main pressure chamber 98 , the first piston 96 is pushed into its initial position, the seal 132 being in close contact with the housing 94 . At this stage, there is a master cylinder pressure P _MC in the master pressure chamber 98 corresponding to a force obtained by the sliding resistance between the seal 132 and the housing 94 from the pressing force of the first spring 106 or the second spring 116 holding the first piston 96 pressurized, subtracted.

In the case of the brake stroke simulator 130 , the sliding resistance between the seal 132 and the housing 94 affects the master cylinder pressure P _MC as described above. Therefore, in a Bremsvorrich device in which the brake stroke simulator 130 is used, there is a tendency for the master cylinder pressure P _MC , ie the pedal action force, to be relatively high or large during an increase in the pedal stroke S and relatively low or small during a decrease in the pedal stroke S becomes small.

In the case of the brake stroke simulator 130 in this embodiment, the characteristic of the pedal reaction force between an increase and a decrease in the pedal stroke S thus has a hysteresis. The hysteresis of the characteristic of the pedal reaction force decreases with a decrease in the sliding resistance between the seal 132 and the housing 94 . The seal 132 is elastically deformed radially outwards in this embodiment, whereby the close contact with the housing 94 is improved during an increase in the pedal stroke S. A large sliding resistance therefore arises between the seal 132 and the housing 94 . During a decrease in the pedal stroke S there is an elastic deformation of the seal 132 radially inward. Therefore, the sliding resistance between the seal 132 and the housing 94 is reduced to a relatively low value.

The brake stroke simulator 92 in the first embodiment is provided with the O-ring 100 for sealing between the first piston 96 and the housing 94 , as described above. The O-ring 100 produces substantially the same sliding resistance during an increase as well as during a decrease in the pedal stroke S. Therefore, the brake stroke simulator 92 in the first embodiment is likely to have a relatively strong hysteresis in the pedal reaction force racing line.

The seal 132 in the third embodiment is designed so that the seal 132 , when it elastically deforms radially outward, creates a sliding resistance substantially equivalent to that generated by the O-ring 100 in the first embodiment. and, when it elastically deforms radially inward, creates a sliding resistance that is significantly less than that that the O-ring 100 generates. Accordingly, the brake stroke simulator 130 in the third embodiment generates a larger pedal reaction force than the brake stroke simulator 92 in the first embodiment while decreasing the pedal stroke S. With the brake stroke simulator 130 , the hysteresis occurring between an increase and a decrease in the pedal stroke S in the characteristic of the pedal reaction can be reduced. Therefore, the braking stroke simulator 130 in the third embodiment achieves a better braking feeling.

A fourth embodiment of the invention will now be described with reference to FIG. 8. Fig. 8 shows a sectional view of the brake stroke simulator 140 according to the fourth embodiment. The ver comparable with those components in Fig. 2 components are referred to in Fig. 8 with the same reference characters and are no longer explained.

The brake stroke simulator 140 in this embodiment has a third piston 142 and fourth piston 144 in the housing 94 . The third piston 142 is arranged displaceably in the fourth piston 144 . The fourth piston 144 has a stepped section 145 , which limits the displacement of the third piston 142 . As shown in FIG. 8, the third piston 142 can be shifted to the left relative to the fourth piston 144 until it contacts the stepped section 145 .

The end face 147 of the third piston 142 as well as the end face 149 of the fourth piston 144 are exposed to the pressure in the main pressure chamber 98 . The end face 147 of the third piston 142 exposed to the pressure in the main pressure chamber 98 has a cross-sectional area A3. The end face 149 of the fourth piston 144 exposed to the pressure in the main pressure chamber 98 has a cross-sectional area A4. When the master cylinder pressure P _MC prevails in the master cylinder 98 , the third piston 142 and the fourth piston 144 each take the force F3 or F4 acting to the left in FIG. 8, which is represented by F3 = P _MC oA3 or F4 = Let P express _MC oA4.

The third piston 142 is provided with an O-ring 146 and a support ring 148 . The O-ring 146 seals the gap between the third piston 142 and the fourth piston 144 . The fourth piston 144 is provided with a check valve type seal 150 . The seal 150 seals the gap between the fourth piston 144 and the housing 94 .

A plug 152 is fitted in the housing 94 to thereby close a return chamber 112 . Between the plug 152 and the fourth piston 144 A, a coil spring 154 is arranged. The coil spring 154 generates a force that pushes the fourth piston 144 away from the sealing plug 152 . The third piston 142 and the fourth piston 144 are pushed to the plug 152 ge when the master cylinder pressure P _MC in the main pressure chamber 98 rises and the pressure force of the Schraubenfe 154 predominates.

The plug 152 has a piston stop 156 . In FIG. 8, the third piston 142 and fourth piston 144 are arranged in their starting positions. The brake stroke simulator 140 is designed such that when the third piston 142 and the fourth piston 144 are in their initial positions, a gap G3 or G4 (<G3) of between the third piston 142 and the fourth piston 144 and the piston stop 156, respectively a certain size is formed, as shown in Fig. 8. The third piston 142 and the fourth piston 144 can be pushed towards the plug 152 until they contact the piston stop 156 . Therefore, the third piston 142 and the fourth piston 144 can be pushed out of their respective starting positions by a certain distance G3 or G4 towards the sealing plug 152 .

In the case in which the Bremshubsi is used mulator 140 in this embodiment, a brake device, the brake fluid flows during increase of the pedal stroke S in the main pressure chamber 98th When the brake fluid flows into the main pressure chamber 98 , the third piston 142 and the fourth piston 144 are pushed toward the sealing plug 152 . At this stage, the relationship between the amount of brake fluid Q _MC flowing into the main pressure chamber 98 and the displacement L of the third piston 142 and the fourth piston 144 can be expressed as follows:

Q _MC = Lo (A3 + A4) (1)

Assuming that the amount of elastic deformation of the coil spring 154 is as large as the displacement L, the relationship between the displacement L and the master cylinder pressure P _MC can be calculated using the spring constant K of the coil spring 154 with the following equation express:

KoL = P _MC o (A3 + A4) (2)

Equations (1) and (2) can be used to express the relationship between the amount of brake fluid Q _MC and the master cylinder pressure P _MC as follows:

P _MC = KoQ _MC / (A3 + A4) ² (3)

Between the inflow amount of brake fluid Q _MC and the pedal stroke S there is an essentially proportional relationship. Using equation (3), the relationship between the pedal stroke S and the master cylinder pressure P _{MC can} thus be expressed as follows:

P _MC = {K '/ (A3 + A4) ² } oS (4)

where K 'is a constant obtained by multiplying the spring constant K of the coil spring 154 by the proportionality factor between the pedal stroke S and the amount of brake fluid Q _MC flowing in.

In the case of the brake stroke simulator 140 in this embodiment, the relationship expressed by the equation (4) between the master cylinder pressure P _MC and the pedal stroke S thus exists in the event that the third piston 142 and the fourth piston 144 are shifted with a change in the pedal stroke S. become, that is, in the event that the displacement L of the third piston 142 and the fourth piston 144 is smaller than the determined distance G3.

In the case of the brake device in which the brake stroke simulator 140 is used in this embodiment, the third piston 142 contacts the piston stop 156 when the pedal stroke S reaches a certain size. After the third piston 142 contacts the piston stop 156 , the third piston 142 can no longer be displaced even if the inflowing brake fluid quantity Q _MC increases with an increase in the pedal stroke S. Therefore, after the contact of the third piston 142 with the piston stop 156, only the fourth piston 144 is pushed further when the pedal stroke S increases further.

In a range in which only an additional displacement L of the fourth piston 144 is possible with an increase in the pedal stroke S, the relationship between the flow of brake fluid Q _MC and the displacement L of the fourth piston 144 can be expressed as follows:

Q _MC = G3oA3 + LoA4 (5)

Assuming that the amount of elastic deformation of the coil spring 154 is as large as the displacement L of the fourth piston 144 , the relationship between the displacement L and the master cylinder pressure P _MC using the spring constant K of the coil spring 154 can be given by the following equation are expressed:

KoL = P _MC oA ⁴ (6)

Equations (5) and (6) express the relationship between the amount of brake fluid Q _MC and the master cylinder pressure P _MC as follows:

P _MC = Ko (Q _MC - G3oA3) / A4 ² (7)

Between the inflow amount of brake fluid Q _MC and the pedal stroke S there is an essentially proportional relationship. Using equation (7), therefore, the relationship between the pedal stroke S and the master cylinder pressure P _MC can be expressed as follows:

P _MC = (K '/ A4 ² ) oS - P ₀ (8)

where K 'is a constant which is obtained by multiplying the spring constant K of the coil spring 154 by the proportionality factor between the pedal stroke S and the inflow amount of brake fluid Q _MC , and P0 represents a constant which is given by P ₀ = KoG3oA3 / A4 ² can be pressed.

In the case of the brake stroke simulator 140 in this embodiment, the master cylinder pressure P _MC changes with a change in the pedal stroke S in the range of a relatively small pedal stroke S with a relatively small gradient K '/ (A3 + A4) ² . In the area of a relatively large pedal stroke S, the master cylinder pressure P _MC changes with a change in the pedal stroke S under a relatively large gradient K '/ A4 ² . With the brake stroke simulator 140 , therefore, a non-linear relationship between the pedal stroke S and the pedal reaction force can be obtained, which is similar to the non-linear relationship obtained with the normal brake device.

The characteristic curve of the brake stroke simulator 140 in this embodiment is primarily determined by the features of the third piston 142 , the features of the fourth piston 144 and the features of the coil spring 154 . Deviations in the features of the coil spring 154 can be relatively easily reduced to a small area during their manufacture. Therefore, the brake stroke simulator 140 in this embodiment ensures a constant product quality without large deviations among the characteristics of individual brake stroke simulators.

In the case of the fourth embodiment, a non li-linear pedal reaction force characteristic is obtained by only a single coil spring 154 is used, the third piston 142 and fourth piston 144 with pressure beauf strike and by the distance G3 ben between the third Kol 142 and the Piston stop 156 and the distance G4 between the fourth piston 144 and the piston stop 156 is different. However, the invention is not limited to this embodiment. Various other measures can be taken so that the master cylinder pressure P _MC , under the effect of which the third piston 142 reaches its stroke end, deviates from the master cylinder pressure P _MC , under the effect of which the fourth piston 144 reaches its stroke end. For example, it would also be possible to provide the third piston and fourth piston independently of one another and to use springs with different spring constants, each of which pressurize the third piston and the fourth piston.

The invention has been described above with reference to the described preferred embodiments; however it will noted that the invention is not open to the beard embodiments is limited. Rather, the Invention various modifications and equivalents regulations are covered.

The invention thus relates to a brake stroke simulator to maintain a good feeling of activity when driving witness brake device. The brake stroke simulator has one in Responsive to a master cylinder pressure he slidable Most pistons and one at a distance from the first piston arranged second piston. At a further distance a plug is arranged from the second piston. There is one between the first piston and the second piston first spring arranged by which the pistons from each other be pushed away. Between the plug and the second piston, a second spring is arranged through which the second piston is pushed away from the plug. With the brake stroke simulator according to the invention, one can lower manufacturing-related deviation under the characteristics Never reach individual brake stroke simulators.

Claims (13)

1. brake stroke simulator ( 92 ) for use with a master cylinder ( 12 ), characterized by:
a first piston ( 96 ) which is displaceable by a first distance (G1) and a second distance (G2) in response to a pressure (P _MC ) from the master cylinder ( 12 );
a second piston ( 108 ) which together with the first piston ( 96 ) is displaceable by the second distance (G2) after the first piston ( 96 ) has been displaced by the first distance (G1);
a first spring ( 106 ) pushing the first piston ( 96 ) away from the second piston ( 108 );
a second spring ( 116 ) that urges the second piston ( 108 ) toward the first piston ( 96 ); such as
an elastic member ( 122 , 124 ) which is arranged in a contact position between the first piston ( 96 ) and the second piston ( 108 ). 2. brake stroke simulator ( 92 ) according to claim 1, characterized by further:
a housing ( 94 ) in which the first piston ( 96 ) is net angeord, and
a check valve type sleeve type seal ( 132 ) provided between the first piston ( 96 ) and the housing ( 94 ) to prevent leakage resulting from the pressure (P _MC ) from the master cylinder ( 12 ). 3. brake stroke simulator ( 92 ) according to claim 1 or 2, characterized in that the first piston ( 96 ) a Rohrab section ( 104 ) and the second piston ( 108 ) in the pipe section ( 104 ) slidably arranged Paßab section ( 110 ). 4. Brake stroke simulator ( 92 ) according to claim 3, characterized in that the first spring ( 106 ) is arranged in the tube section ( 104 ). 5. Brake stroke simulator ( 140 ) for use with a master cylinder ( 12 ), characterized by:
a first piston ( 142 ) slidable in response to pressure from the master cylinder ( 12 ) to its stroke end (G3);
a second piston ( 144 ) slidable in response to pressure from the master cylinder ( 12 ) to its stroke end (G4);
at least one coil spring ( 154 ) which urges the first piston ( 142 ) and the second piston ( 144 ) together in a direction opposite to the direction of the force generated by the pressure from the master cylinder ( 12 ), the first piston ( 142 ) and the second piston ( 144 ) are each displaceable in the direction of the force generated under the effect of the pressure from the master cylinder ( 12 ) up to the respective stroke end (G3, G4); such as
a piston stop ( 156 ) which is arranged with respect to the first piston ( 142 ) and the second piston ( 144 ) so that the maximum stroke (G3) of the first piston ( 142 ) is smaller than the maximum stroke (G4) of the second piston ( 144 ),
wherein the pressure from the master cylinder ( 12 ), under the effect of which the first piston ( 142 ) can be displaced up to its stroke de (G3), differs from the pressure from the master cylinder ( 12 ) under whose effect the second piston ( 144 ) can be pushed up to its stroke end (G4). 6. Brake stroke simulator ( 140 ) according to claim 5, characterized in that the first piston ( 142 ) cut a Rohrab and the second piston ( 144 ) has a section in the Rohrab slidably arranged fitting section. 7. brake stroke simulator ( 140 ) according to claim 5, characterized in. that the first piston ( 142 ) is slidably disposed in the second piston ( 144 ). 8. brake stroke simulator ( 140 ) according to claim 7, characterized in that the second piston ( 144 ) by a first distance (G3) and a second distance (G4 - G3) can be pushed ver, and that the first piston ( 142 ) together with the second piston ( 144 ) can be moved by the first distance (G3) before the second piston ( 144 ) has been moved by the second distance (G4 - G3). 9. Braking system, characterized by:
a brake stroke simulator ( 92 , 140 ) according to claim 1 or 5,
a master cylinder ( 12 ) that generates a master cylinder pressure (P _MC ) corresponding to the operation of a brake pedal ( 10 );
a pressure generator ( 14 ) which generates a pressure (P _RE ) equal to the master cylinder pressure (P _MC ),
a pressure switching system that supplies the master cylinder pressure (P _MC ) or the pressure generated by the pressure generator ( 14 ) (P _RE ) to a wheel cylinder, and
a fluid line connecting the wheel cylinder to the main cylinder ( 12 ),
wherein the brake stroke simulator ( 92 , 140 ) is connected to the fluid line connecting the wheel cylinder to the master cylinder ( 12 ) and the pressure switching system is provided on the same side of the brake stroke simulator ( 92 , 140 ) as the wheel cylinder. 10. Brake system according to claim 9, characterized in that the brake stroke simulator ( 92 , 140 ) absorbs only the main cylinder pressure (P _MC ). 11. Procedure for simulating a brake stroke, characterized by the following steps:
Shifting a first piston ( 96 ) by a first distance (G1) and a second distance (G2) by applying a pressure (P _MC ) from a master cylinder ( 12 ),
after displacement of the first piston ( 96 ) by the first distance (G1), displacement of a second piston ( 108 ) together with the first piston ( 96 ) by the second distance (G2),
Pushing the first piston ( 96 ) in a direction away from the second piston ( 108 ),
Pushing the second piston ( 96 ) in a direction towards the first piston ( 96 ), and
Applying an elastic force between the first piston ( 96 ) and the second piston ( 108 ). 12. The method according to claim 11, characterized by the further steps:
Placing the first piston ( 96 ) in a housing ( 94 ), and
Preventing a leakage between the first piston ( 12 ) and the housing ( 94 ) resulting from the pressure (P _MC ) from the main cylinder ( 12 ). 13. Method for simulating a brake stroke, characterized by the following steps:
Moving a first piston ( 142 ) to the end of a first stroke (G3) by applying a first pressure from a master cylinder ( 12 ),
Moving a second piston ( 144 ) to the end of a second stroke (G4) by applying a second pressure from the master cylinder ( 12 ),
Pushing the first piston ( 142 ) and the second piston ( 144 ) in a direction opposite to the direction of a force generated under the action of the pressure from the master cylinder ( 12 ),
Limiting the stroke of the first piston ( 142 ) so that the stroke of the first piston ( 142 ) is less than the stroke of the second piston ( 144 ), and
Compressing the first piston ( 142 ) and the second piston ( 144 ),
wherein the first pressure differs from the second pressure.