Hydraulic power-assisted vehicle brake device and method for filling the hydraulic power-assisted vehicle brake device

Abstract

The present invention proposes connecting a pedal travel simulator (16) of a hydraulic booster vehicle brake device (1) to a brake fluid tank (13) via a groove between two piston seals (21) of a booster brake pressure generator (3), whereby any air bubbles in the brake fluid flow from the pedal travel simulator (16) into the brake fluid tank (13) and the piston seal (21) is lubricated by the brake fluid.

Description

Technical Field

[0001] The invention relates to a hydraulic power-assisted vehicle brake device having the features of the preamble of claim 1 and a method for filling a hydraulic power-assisted vehicle brake device according to the features of the preamble of claim 7 . Background Art

[0002] International patent application WO 2012 / 150 120 A1 discloses a hydraulically powered vehicle brake device with a manually operable master brake cylinder and a power-assisted brake pressure generator with a piston-cylinder unit, the piston of which can be moved in a cylinder body by means of an electric motor via a threaded transmission mechanism in order to generate brake pressure. The master brake cylinder is used as a set value for the brake pressure to be generated by means of the power-assisted brake pressure generator. A piston-cylinder unit with a spring-loaded simulator piston is connected to the master brake cylinder as a pedal travel simulator, in the simulator cylinder of which brake fluid can be discharged from the master brake cylinder, whereby a master brake cylinder piston and a foot brake pedal can be moved when the master brake cylinder is hydraulically separated from the vehicle brake device by closing a clutch valve during power-assisted operation of the vehicle brake device. Summary of the invention

[0003] The hydraulic booster-vehicle brake device according to the invention with the features of claim 1 comprises a master brake cylinder, a particularly pressureless brake fluid reservoir, a booster brake pressure generator, one or more hydraulic wheel brakes and a pedal travel simulator with a piston-cylinder unit with a simulator piston that can move in a simulator cylinder. The wheel brakes are connected to the booster brake pressure generator, particularly via inlet valves, so that the wheel brakes can be actuated by means of the booster brake pressure generator. Preferably, the wheel brakes are connected to the master brake cylinder, also via valves, so that in the event of a failure or an error in the booster brake pressure generator, the wheel brakes can be actuated by means of the master brake cylinder.

[0004] The master brake cylinder can be actuated by manpower, for example, via a foot brake pedal or a hand brake lever, and can also have a brake booster, so that the master brake cylinder can be power-assisted actuated, that is, amplified by manpower through the boost of the brake booster.

[0005] During power-assisted actuation, the master brake cylinder is hydraulically separated from the rest of the vehicle brake system by closing the clutch valve and connected to the simulator cylinder of the pedal travel simulator on the front side of the simulator piston, so that brake fluid can be discharged from the master brake cylinder into the simulator cylinder. As a result, a master brake cylinder piston can be moved in the master brake cylinder and the foot brake pedal or hand brake lever can be moved. In particular, the simulator piston is spring-loaded so that the simulator piston provides a resistance to the brake fluid discharged from the master brake cylinder into it that increases as the piston stroke increases, so that the actuation force of the master brake cylinder increases as the foot pedal stroke or hand brake lever stroke increases, as in a conventional hydraulic vehicle brake system.

[0006] On the rear side of the simulator piston, the simulator cylinder is connected according to the invention to a brake fluid tank so that when the simulator piston moves in the simulator cylinder, the simulator piston discharges brake fluid from the simulator cylinder into the brake fluid tank on the rear side of the simulator piston. This makes it possible to fill the simulator cylinder on the rear side of the simulator piston in addition to the front side of the simulator piston, so that the simulator piston is lubricated from both sides with brake fluid. When moving the simulator piston, air that may be contained in the simulator cylinder on the rear side of the simulator piston is discharged from the simulator cylinder into the brake fluid tank, where the air escapes from the brake fluid.

[0007] The dependent claims have as their subject matter developments and advantageous embodiments of the invention which are specified in the independent claims.

[0008] All features disclosed in the description and drawings can be implemented in the embodiments of the present invention individually or in any combination. The following design of the present invention is possible in principle: the design does not have all the features of the claims or the embodiments of the present invention, but only has one or more features of the claims or the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Next, the present invention will be further described with the aid of the embodiments shown in the accompanying drawings. The accompanying drawings show:

[0010] Figure 1 A hydraulic circuit diagram of a hydraulic power-assisted vehicle brake device according to the present invention;

[0011] Figure 2 From Figure 1 Individual parts of the hydraulic circuit diagram; and

[0012] Figure 3According to the present invention, Figure 1 Hydraulic integrated block for vehicle braking device. DETAILED DESCRIPTION

[0013] exist Figure 1 The hydraulic servo-assisted vehicle brake device 1 according to the invention shown in FIG. 1 further comprises a dual-circuit master brake cylinder 2 which can be activated by human power and a servo-assisted brake pressure generator 3 , to which hydraulic wheel brakes 6 are connected via servo-assisted valves 4 and inlet valves 5 .

[0014] The booster brake pressure generator 3 has a piston-cylinder unit 7 with a booster piston 8, which can be moved in a booster cylinder 9 for generating brake pressure. The booster piston 8 can be moved in the booster cylinder 9 by means of an electric motor 10 via a screw transmission 11 (for example, a ball screw transmission or, in general, a rotation-translation conversion transmission). Between the electric motor 10 and the rotation-translation conversion transmission, for example, a planetary gear transmission can be arranged as a mechanical reduction transmission (not shown).

[0015] In the present embodiment, the vehicle brake device 1 has two brake circuits I, II and four wheel brakes 6, wherein every two wheel brakes are assigned to one of the brake circuits I, II. In each brake circuit I, II, the wheel brakes 6 of the respective brake circuits I, II are connected to the booster brake pressure generator 3 via a booster valve 4 and an inlet valve 5 assigned to the brake circuit.

[0016] Each wheel brake 6 is assigned a discharge valve 12 , via which the wheel brake 6 is connected to a pressure-free brake fluid reservoir 13 situated on the master brake cylinder 2 .

[0017] The inlet valve 5 and the discharge valve 12 form a wheel brake pressure regulating valve system, with which a slip control can be performed. Such slip control is, for example, an anti-lock control, a drive slip control and / or a driving dynamics control or an electronic stability program, for which the abbreviations ABS, ASR, and / or FDR or ESP are often used. Such slip control is well known and will not be explained further here. The slip control can also have, for example, a piston pump or an (internal) gear pump that can be driven by an electric motor as a hydraulic pump (not shown) in each brake circuit I, II. Such a hydraulic pump for slip control is also called a return pump (Rückförderpumpe).

[0018] A different number of wheel brakes 6 and an assignment to the brake circuits I, II are possible.

[0019] The wheel brakes 6 are connected in each brake circuit I, II via a disconnect valve 14 and the inlet valve 5 to the master brake cylinder 2 , so that the wheel brakes 6 can be actuated by the master brake cylinder 2 if the booster brake pressure generator 3 stops functioning or fails.

[0020] In one of the two brake circuits, a pedal travel simulator 16 is connected to the master brake cylinder 2 via a simulator valve 15. The pedal travel simulator 16 has a piston-cylinder unit with a simulator cylinder 17, in which a spring-loaded simulator piston 18 is axially movable. On the front side of the simulator piston 18, the simulator cylinder 17 is connected to the master brake cylinder 2 via a simulator valve 15. On the rear side of the simulator piston 18, the simulator cylinder 17 is connected to a pressureless brake fluid reservoir 13.

[0021] During boosted braking, the master brake cylinder 2 is hydraulically separated from the vehicle brake system 1 or the wheel brake 6 by closing the clutch valve 14 and connected to the pedal travel simulator 16 by opening the simulator valve 15, so that the brake fluid can be discharged from the master brake cylinder 2 on the front side of the simulator piston 18 into the simulator cylinder 17. The brake pressure is generated by the booster brake pressure generator 3, which is connected to the wheel brake 6 by opening the booster valve 4. The brake pressure can be adjusted by the forward and backward movement of the booster piston 8 in the booster cylinder 9. The brake pressure is adjusted according to the actuation of the master brake cylinder 2, which is used as a setter for the brake pressure to be generated by the booster brake pressure generator 3 during boosted braking. For this purpose, the master brake cylinder 2 has a pressure sensor 19 and a displacement sensor 20. In principle, one sensor 19, 20 is sufficient, and the second sensor 20, 19 is provided for redundancy.

[0022] The booster valve 4, the inlet valve 5, the discharge valve 12, the clutch valve 14 and the simulator valve 15 are two-position two-way solenoid valves, wherein the inlet valve 5 and the clutch valve 14 are open in their de-energized initial positions, and the booster valve 4, the discharge valve 12 and the simulator valve 15 are closed in their de-energized initial positions. Other designs of the valves and their switched-on positions are possible.

[0023] The booster cylinder 9 of the piston-cylinder unit 7 of the booster brake pressure generator 3 has two axially offset piston seals 21, and the booster cylinder 9 is connected to the brake fluid reservoir 13 through the two piston seals. For this purpose, the booster cylinder 9 has a circumferential groove between the piston seals 21, which surrounds the circumference of the booster piston 8 and connects the brake fluid pipeline 22 from the pedal travel simulator 16 to the brake fluid pipeline 23 leading to the brake fluid reservoir 13. The groove in the booster cylinder 9 that connects the brake fluid pipelines 22 and 23 extends over the entire circumference or part of the circumference.

[0024] The vehicle brake system 1 may have a modular structure, for example, the master brake cylinder 2 and the booster brake pressure generator 3 may be arranged in a module or in a hydraulic integrated block, and the slip adjustment may be arranged in another module or in another hydraulic integrated block (not shown). The master brake cylinder 2 and the booster brake pressure generator 3 may also be arranged in their own modules or hydraulic integrated blocks (not shown). However, a design of the vehicle brake system 1 having a module or a hydraulic integrated block is also possible.

[0025] Figure 3 The rectangular parallelepiped hydraulic integrated block 24 of the vehicle brake system 1 is shown. The rectangular parallelepiped hydraulic integrated block has a hole as a receiving portion for the above-described components of the vehicle brake system 1, and the rectangular parallelepiped hydraulic integrated block is according to Figure 1 The hydraulic circuit diagram in the housing is used for drilling, that is, the elements arranged in the housing are connected to each other according to the hydraulic circuit diagram. In the side view, the hydraulic integrated block 24 is approximately square, and the width of the hydraulic integrated block is approximately 1 / 4 to 1 / 3 of the length and / or height. Figure 3 The hydraulic block 24 is shown in the set installation and use position, in which the narrow side as the upper side 25 is located at the top. Figure 3 The brake fluid reservoir 13 , not shown, is placed on the upper side 25 .

[0026] In the large side of the hydraulic block 24 facing the observer (here referred to as the motor side 26), the booster cylinder bore, which forms the booster cylinder 9 of the booster brake pressure generator 3, is arranged, and next to it, the simulator cylinder bore, which forms the simulator cylinder 17, is arranged. In the installation and use position, the booster cylinder bore and the simulator cylinder bore, and therefore the booster cylinder 9 and the simulator cylinder 17, are horizontal. Above the booster cylinder 9, that is, between the booster cylinder 9 and the upper side 25, parallel to the upper side 25 and parallel to the motor side 26, the master brake cylinder bore, which forms the master brake cylinder 2, is arranged in the hydraulic block 24, and in the installation and use position, the master brake cylinder bore also extends horizontally and perpendicularly to the booster cylinder 9 and the simulator cylinder 17.

[0027] The dotted circular line is used to draw the inner circumference of the booster cylinder 9 surrounding the booster piston 8. Figure 3 The groove 27 between the two piston seals 21, which cannot be seen in the figure, connects the brake fluid pipeline 22 from the pedal travel simulator 16 to the brake fluid pipeline 23 leading to the brake fluid reservoir 13. The brake fluid pipeline 23 leads vertically upward to the counterbore 28 of the connecting joint for the brake fluid reservoir 13 in the upper side 25 of the hydraulic manifold 24. When the brake fluid reservoir 13 is placed on the upper side 25 of the hydraulic manifold 24, the connecting joint (not shown) of the brake fluid reservoir 13 is inserted into the counterbore 28, so that the brake fluid reservoir 13 is connected to the brake pipeline 23. The brake pipeline 23 leads to the groove 27 of the booster cylinder 9 from above.

[0028] The brake fluid line 22 from the pedal travel simulator 16 intersects the simulator cylinder 17, which is horizontal in the installation and use position, at the upper side and opens radially into the groove 27 of the booster cylinder 9. Since the brake fluid line 22 is connected to the simulator cylinder 17 at the top, the air that may be contained in the brake fluid is discharged from the simulator cylinder 17 on the rear side of the simulator piston 18 together with the brake fluid and reaches the brake fluid reservoir 13 through the brake fluid lines 22, 23 and the groove 27 of the booster cylinder 9 as shown by the arrow 29, where the air escapes from the brake fluid. In the illustrated installation and use position of the hydraulic manifold 24, the simulator cylinder 17 is installed deeper than the booster cylinder 9 so that air bubbles escape upward from the simulator cylinder 17.

[0029] During each booster braking, the master brake cylinder 2 (which serves as a set valuer for the brake pressure to be generated by the booster brake pressure generator 3) is operated. The simulator valve 15 is opened, so that the master brake cylinder 2 discharges the brake fluid into the simulator cylinder 17. As a result, the simulator piston 18 moves in the simulator cylinder 17 and discharges the brake fluid from the simulator cylinder 17 on the rear side of the simulator piston through the brake fluid pipeline 22, the groove 7 around the booster piston 8 between the two piston seals 21 in the booster cylinder 9, and the brake fluid pipeline 23 to the brake fluid reservoir 13 (see Figure 2 ), in which any air bubbles contained in the brake fluid escape from the brake fluid. When the master brake cylinder 2 is released, the brake fluid is sucked from the brake fluid tank 13 into the simulator cylinder 17 on the rear side of the simulator piston 18 in the opposite direction.

[0030] Since brake fluid is present in the simulator cylinder 17 , on the front and rear sides of the simulator piston 18 , and in the groove 27 between the two piston seals 21 , the simulator piston 18 and the piston seals 21 are lubricated from both sides with the brake fluid.

[0031] Since the brake fluid flows into the groove 27 around the booster piston 8 between the two piston seals 21 in the booster cylinder 9 as described above each time the simulator piston 18 moves in the simulator cylinder 17, the two piston seals 21 are lubricated. The booster piston 8 delivers the brake fluid from the groove 27 to the two piston seals 21 by its back and forth movement in the booster cylinder 9. As described in Figure 2 As can be seen in the figure, the two piston seals 21 are lamellar seals, that is, seals that can only overflow in one direction in the manner of a non-return valve. Since no brake fluid passes through the high-pressure side piston seal 21 (on the right in the figure) to the low-pressure side piston seal (on the left in the figure), the brake fluid supply line between the two piston seals 21 is important for lubricating the low-pressure side piston seal 21.

[0032] The vehicle brake system 1 can be vented as is customary in slip-controlled vehicle brake systems and subsequently filled with brake fluid, preferably under pressure. However, filling without venting is also possible by injecting pressurized or unpressurized brake fluid into the vehicle brake system 1 via the brake fluid reservoir 13. When the simulator valve 15 is opened, the master brake cylinder 2 is then actuated several times and the brake fluid on the front side of the simulator piston 18 is discharged into the simulator cylinder 17, whereby the simulator piston 18 moves in the simulator cylinder 17. On its rear side, the simulator piston 18 discharges the brake fluid from the simulator cylinder 17 through the brake fluid line 22, the groove 27 in the booster cylinder 9 between the two piston seals 21 around the booster piston 8, and the brake fluid line 23 into the brake fluid reservoir 13, where the air contained in the brake fluid escapes. When the master brake cylinder 2 is released, the brake fluid without air (!) is sucked from the brake fluid reservoir 13 in the opposite direction to the simulator cylinder 17 on the rear side of the simulator piston 18. By repeating this process several times, the simulator cylinder 17 is vented of air on the rear side of the simulator piston 18 (and also on the front side of the simulator piston!).

Claims

1. A hydraulic booster vehicle brake system having a master brake cylinder (2), a brake fluid reservoir (13), a booster brake pressure generator (3), hydraulic wheel brakes (6) which can be actuated by means of the booster brake pressure generator (3), and a pedal travel simulator (16) having a piston-cylinder unit with a simulator piston (18) which can be moved in a simulator cylinder (17), in, The simulator cylinder (17) is connected to the master brake cylinder (2) on the front side of the simulator piston (18), and is characterized in that the simulator cylinder (17) is connected to the brake fluid storage tank (13) on the rear side of the simulator piston (18), the booster brake pressure generator (3) has a piston-cylinder unit (7), the booster piston (8) of the piston-cylinder unit is sealed in the booster cylinder (9) by means of two axially offset piston seals (21), and the simulator cylinder (17) is connected to the brake fluid storage tank (13) on the rear side of the simulator piston (18) through the two piston seals (21) of the piston-cylinder unit (7) of the booster cylinder (9).

2. The hydraulic power-assisted vehicle brake device according to claim 1, It is characterized in that The booster cylinder (9) has a circumferential groove (27) between the two piston seals (21), which surrounds the booster piston (8), and the simulator cylinder (17) is connected to the brake fluid tank (13) on the rear side of the simulator piston (18) via the groove.

3. The hydraulic power-assisted vehicle brake device according to claim 1 or 2, It is characterized in that The simulator cylinder (17) is connected to the brake fluid reservoir (13) on the rear side of the simulator piston (18) at a position of the simulator cylinder (17) which is located at the top in the installation and use position.

4. The hydraulic power-assisted vehicle brake device according to claim 1 or 2, It is characterized in that The simulator cylinder (17) has a horizontal installation and use position.

5. The hydraulic power-assisted vehicle brake device according to claim 3, It is characterized in that In the installation and use position, the simulator cylinder (17) is arranged deeper than the booster cylinder (9).

6. Method for filling a hydraulic power-assisted vehicle brake system according to claim 1 with brake fluid, It is characterized in that In order to fill the vehicle brake system (1) with brake fluid, the brake fluid is injected into the vehicle brake system (1) through the brake fluid reservoir (13), and the master brake cylinder (2) is actuated multiple times, so that the simulator piston (18) moves back and forth multiple times in the simulator cylinder (17), and in this process, the brake fluid is discharged from the simulator cylinder (17) into the brake fluid reservoir (13) multiple times on the rear side of the simulator piston (18), and is sucked back from the brake fluid reservoir (13) into the simulator cylinder (17) on the rear side of the simulator piston (18).

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