EP1137563A1

EP1137563A1 - Hydraulic intensifier operating as a pressure intensifier

Info

Publication number: EP1137563A1
Application number: EP99963406A
Authority: EP
Inventors: Hans-Jörg Feigel
Original assignee: Continental Teves AG and Co OHG
Current assignee: Continental Teves AG and Co OHG
Priority date: 1998-12-09
Filing date: 1999-12-07
Publication date: 2001-10-04
Also published as: WO2000034097A1

Abstract

The invention relates to a hydraulic intensifier, especially for ABS systems. In order to provide a low-noise hydraulic intensifier (8) that can be adjusted in a precise manner and is easy to assemble, the inventive intensifier is fitted with a continuously operating positive-displacement pump (1). Adjustment is carried out with the aid of a sensor device. The input pressure (pF) of the pump (1) is increased according to a gain factor (MU) and compared with the output pressure (pV) of the pump. The pressure differential (uD) is used to determine the torque that is exerted by a motor on said pump, resulting in said pressure gain.

Description

Hydraulic booster working as a pressure booster

Hydraulic amplifiers are becoming increasingly important in technology. This applies in particular to amplifiers in motor vehicles in which the amplifiers to be installed are to be as compact as possible. The vacuum amplifiers that have been used regularly up to now can often no longer be used effectively, because on the one hand they require a considerable amount of space and on the other hand the vacuum required for amplification is no longer available in more modern vehicles. Another advantage of hydraulic boosters, particularly in connection with brake systems, is that there is no longer any break with regard to the working medium (liquid), that is to say, air and liquid are not used simultaneously within the control device.

The use of hydraulic boosters in controlled brake systems is known per se. However, the known hydraulic amplifiers were comparatively complex and could only be regulated relatively inaccurately. The present invention is therefore based on a hydraulic amplifier, in particular for controlled brake systems. The object of the present invention is to improve such amplifiers with regard to their control behavior, their dimensions and their smoothness.

The object is achieved by the combination of features resulting from the characterizing part of claim 1. In principle, the present invention therefore consists in continuously promoting hydraulic amplification Use positive displacement pump. The force exerted on the displacers due to the inlet pressure is amplified by a connected electric motor until the outlet pressure at the pump corresponds to the desired pressure which is dependent on the inlet pressure.

It is particularly advantageous in such a pump that a low-pulsation and quiet pressure build-up for actuating connected actuation devices, for example hydraulically actuated disc brakes, is achieved. There is no media break within the entire control loop, since both the amplifier and the brake actuation circuits work hydraulically. The brake booster according to the invention also makes it possible to dispense with the known vacuum brake boosters and the brake booster according to the invention is furthermore particularly suitable for modern injection engines in that the vacuum required for the conventional vacuum booster is no longer available. The present brake booster does not need a separate hydraulic accumulator and, for the reasons mentioned above, does not require a separate vacuum pump and is therefore very inexpensive overall.

In a further development of the invention, gear pumps, vane cell pumps and spindle pumps have proven to be particularly suitable as continuously demanding displacement pumps. With regard to the electric motor, in a further development of the invention the brake booster according to the invention can be simplified by the use of a brushless, permanently excited DC motor and the admissibility increased. In order to To prevent that the pressurized liquid, in particular brake liquid, present in the brake circuits can be reclaimed via the pump to the actuating element (THZ), it is advisable in a further development of the invention to incorporate a check valve into the input and / or output line of the pump. With regard to the brushless, permanently excited DC motor, it must also be added that it can be operated at idle even when the brake pressure is not required, so that it is generally not necessary to start the motor when the brake pressure is required.

For the valve device there is a special structure by using the combination of features according to claim 7. It is particularly important that the valve device must be controllable in an analog manner in order to obtain a simple structure of the brake booster according to the invention and to achieve a comfortable pressure reduction.

While it is possible per se to regulate the torque exerted by the electric motor on the pump as a function of the torque exerted by the input pressure of the pump on the displacer body of the pump, the feature combination according to claim 8 is recommended in a further development of the invention measured at the inlet and at the outlet of the pump and determined the desired pressure at the outlet of the pump as a function of the inlet pressure. A particularly simple and mechanically operating device for determining the torque to be exerted on the pump by the electric motor can be seen from the combination of features according to claim 9. The pressure compensator described there compares output pressure and input pressure via two pistons which are driven in opposite directions and are coupled to one another, the transmission ratio being determined by the differently sized piston surfaces are introduced into the comparison process within the scale. The pressure compensator is in its balanced state when the outlet pressure of a pump is equal to the inlet pressure of the same pump, which is increased by the amplification factor. If the pressure compensator deviates from its balanced state or its position describing this state, this positional deviation serves as a measure of the control deviation of the pump pressure, the positional deviation of the pump being able to actuate an electrical actuator at the same time. Another solution already proposed above is to use transducers to generate electrical output voltages which correspond to the inlet pressure or the outlet pressure of the pump in order to readjust the motor force exerted on the pump via the voltage difference.

In order to start the actuation of the brakes more quickly and to overcome the initial frictional resistances in the brake mechanics more quickly, in a further development of the invention the combination of features according to claim 12 is recommended. If one wants to ensure that the very high brake pressure desired by the driver is really the one for If the brake system reaches the maximum possible brake pressure on the brakes, then in a further development the combination of features according to claim 13 is recommended. It is taken into account that the driver is either psychologically or physically unable to specify the maximum possible brake pressure despite the recognized large dangerous situation.

A further improvement of the brake booster according to the invention can be achieved by using the features according to claim 14. The brake pressure generated by the pump is not only that of Driver caused input pressure but also the speed with which this brake pressure is built up at the input. The control algorithm on which this is based assumes that if the brake is actuated quickly, there is also a particular risk potential for the driver.

In order to carry out the brake pressure reduction particularly quickly, the feature combination according to claim 15 is recommended in a further development of the invention. In other words, this means that the valve device has SO valves which are opened in the event of a desired brake pressure reduction. As a result, the output of the pump is either returned to its input and thus the pump is short-circuited or, if necessary, the pump input is connected to the brake pressure transmitter, which at least partially reclaims the brake fluid in it. The brake booster according to the invention is excellently suited to be interconnected with an ABS control device in accordance with the combination of features according to claim 16. The advantage here is that by interconnecting the output of the ABS pump with the input of the booster pump, only small pressures have to be generated by the ABS pump, so that the ABS pump can be dimensioned weak.

In a further development of the invention it can also be achieved that the electric motor of the ABS pump is omitted and the ABS pump is additionally driven by the electric motor of the brake booster. A further simplification of the brake system can be achieved by using the features according to claim 18. The pump of the brake booster is also used as an ABS pump, which is done with the help of a Switching valve between the brake pressure sensor and the pump input of the brake pump can be effected.

A particular advantage of using the brake booster with the aid of an ABS system can be achieved by using the features according to claim 19, in that the low-pressure accumulators are omitted and the connection of these low-pressure accumulators is connected to the container.

From the above-mentioned simplifications and summaries, the feature combination according to claim 20 can be achieved in a further development, in that the brake booster and the ABS system are structurally combined in a common assembly, which further saves connection lines and installation space.

In accordance with the development according to claim 21, the present amplifier is also excellently suited to be used not only in connection with ABS but also in connection with ESP systems for performing their functions.

An exemplary embodiment of the invention is explained below with reference to the drawing. It shows:

Fig. 1 built for two circles

Brake booster with a downstream ABS device,

Fig. 2 shows the same structure as in Fig. 1, the

Motor of the brake booster operates the ABS pumps at the same time Fig. 3 shows the structure of FIG. 2, the task of ABS-Pu taken over by the booster pumps and at the same time the

Low pressure booster of the ABS system were omitted

4 shows the structure according to FIG. 3, the assemblies of the ABS device and the brake booster being spatially combined in a common assembly and the low-pressure accumulator of the ABS device being added,

Fig. 5 shows the structure of Fig. 3, wherein in Fig. 5, the low pressure accumulator was added and

Fig. 6 shows the structure and operation of the sensor devices not shown in detail in the previous figures.

In Fig. 1 the brake system shown there is divided into two brake circuits. Since these brake circuits are shown symmetrically in FIG. 1, only the right-hand brake circuit in FIG. 1 will be stated below.

In Fig. 1 em brake pressure sensor 4 is shown in the form of a tandem main cylinder, on the first piston 5 with the help of a pedal lever 6 a force and thus em pressure in the cylinder chamber 7 is applied. This pressure is fed to a brake booster 8 as input pressure pF and is fed from this brake booster via an ABS device 9 to brakes HL, VR. To understand the invention, the ABS device 9 is not absolutely necessary and can therefore be omitted. In the event that the brake booster is ineffective, the pressure generated in the cylinder space 7 is thus applied to the brakes HL, VR. The following considerations also assume that the ABS device 9 has been removed, so that the output line 11 of the brake booster is connected to the brake lines 13, 14 of the brakes HL and VR. It is thus always possible, by actuating the pedal lever 6, to exert a braking effect on the brakes HL, VR.

In Fig. 1 it is now assumed that the

Brake booster 1 is switched on, ie the motor 2 can be supplied with current by a control device, so that it can drive the pump 1. A possible embodiment of the control device not shown in FIG. 1 is shown in FIG. 6. The force to be exerted by the engine and thus the driving torque of the engine is determined as follows: It is measured as the input pressure, the pressure pF generated in the cylinder space via the pedals 6 via a converter 15 and at the same time the increased pressure pV at the output of the Pump measured with the converter 16. The resulting voltages uF and uV, as can be seen in FIG. 6, are fed to a comparator VG, the voltage uF reaching the comparator VG by the amplification factor, for example the amplification factor 4, via a multiplier MU. The comparator compares the two voltages and thus measures the voltage uD which is fed into an electronic circuit ECU. Because of the size of UD, the ECU determines the voltage uM or the corresponding current to be supplied to the motor, as a result of which torque is exerted by the motor on the pump P. The torque amplifies the output voltage uV and thus UV2, which makes the Differential voltage uD is reduced and the torque is adjusted to the target voltage uV2.

A prerequisite for the correct execution of the process described is that the SO valve of the valve device 3 is closed, so that the pump 1 is not operated in idle mode, but rather requires pressure medium from the cylinder space 7 in the direction of the brakes HL, VR. The switchover of the SO valve in the valve device 3, in its actuation, can be triggered, for example, by a change in pressure at the input of the pump 1 due to the change in force on the pedal lever 6. However, it can also prove to be advantageous to combine with the piston 5 or its actuating plunger a displacement sensor, not shown in FIG. 1, when actuated, the valve device 3 blocks.

If the brake pressure built up by the pump 1 is to be reduced in the brakes HL, VR, it is necessary to switch through the valve device 3, that is to say to open it, so that the em and outlet of the pump 1 are short-circuited and the pressure medium from the brakes in the Cylinder chamber 7 can be reclaimed. In this way, the direction of the pressure medium can be reversed without having to change the direction of rotation of the pump. This makes the pump structure and the structure of the motor very simple, since it is sufficient to always turn them in the same direction.

With the operation of the amplifier described above, it is not necessary that an ABS-ASR device 9 between amplifiers and brakes HL, VR is connected, as shown in FIG. 1. The brake booster described is excellent for working together suitable with the facility mentioned. 1 has the structure known per se, in which the input line 11 of the ABS-ASR device is connected as usual to the output line 19 of the master cylinder. The brake fluid is reclaimed via line 10 back into the cylinder space 7 of the master cylinder. Since the ABS-ASR device 9 has the usual structure, it will not be described in more detail here.

The following Figures 2 to 5 are only described to the extent that a deviation from the previous figures can be determined. From an advantageous development of the invention, FIG. 2 shows that the work of the motor 22 in the ABS / ASR device 9 in FIG. 1 can also be carried out by the motor 2 in FIG. 1 or FIG. 2 . In this case, however, care must be taken that the motor 2 only drives the pump or pumps of the ABS ASR system when there is a need. This can be done on the one hand by a corresponding manual transmission if the engine is running continuously or by the fact that the engine is only switched on except for the boosting braking processes when the pumps of the ABS-ASR device 9 are to start.

In FIG. 3, a step further is taken compared to FIG. 2 in that not only the motor 2 of the

Brake booster 8 but also the pump 1 or both pumps of the brake booster 8 take over the task of the motor and pumps in the ABS-ASR device 9. This means that motor 2 and pumps 1 not only start up when the pressure on the brakes HL, VR for braking the vehicle increases, but also start up when in the ASR case motor 2 and pump 1 act on them, when the wheels spin in the ASR case. The control for the second case is done by the ECU of the ABS-ASR device 9. A further difference from FIG. 3 is that the low-pressure accumulators 23, 24 have been omitted in FIG. 1, so that the brake fluid in the ABS case passes from the brakes HL into the container 25 via corresponding accesses within the brake pressure transmitter 4. To prevent the outflowing liquid from getting into the pump 1, check valves (SG valve) are provided.

FIG. 4 differs from FIG. 3 essentially in that, on the one hand, the low-pressure accumulators 23, 24 have been reinserted, but on the other hand, the amplifier 8 and the ABS-ASR device 9 have been structurally combined. The result is a combined ABS / ASR amplifier device 30, which essentially works like the circuit arrangement according to FIG. 3 in connection with FIG. 2. The pump 1 starting in the ASR case can take the necessary liquid from the associated low-pressure container 23, the liquid then reaching the brakes HL and VR from the outlet of the pump.

The draining of the liquid from the brake HL, HR runs into the associated low-pressure accumulator or, if there is no low-pressure accumulator, via the THZ into the container 25.

FIG. 5 shows the structure corresponding to FIG. 4, except that the components in question are divided into two assemblies, which can be referred to as brake booster 8 and ABS / ASR device 9. Another particular advantage of the present invention is that the pump is connected in parallel Valve device 3 with the help of the valve control and thus the connection of the valves, the pressure reduction can be carried out very quickly, while at the same time the pressure build-up via the pump is sufficiently fast. By using a continuously demanding pump, the device is also quite quiet and the pedal feel very even.

Claims

claims

1. Brake booster (8) consisting of a pump (1) which is rotatably driven by an electric motor (2), the input (19) of which is connected to a brake pressure transmitter (4) actuated by the driver and the output (11) of which is connected to the wheel brakes (HL; VR) is connected to a hydraulic connection, which can be shut off with a valve device (3, VE), between the pump inlet (19) and the pump outlet (11) of an electrical sensor device (WF, Wv; Mu; VG), the electric motor (M) and the valve device ( 3; VE) controlling electronics (ECU), characterized in that the pump (1) is designed as a continuously delivering positive displacement pump, in which the moment resulting from the input pressure effect (pF) on the displacer body is amplified by the drive torque applied by the electric motor (2) (Fig. 1 to Fig. 6).

2. Brake booster according to claim 1, characterized in that the pump (1) is a gear pump. (Fig. 1 to Fig. 5)

3. Brake booster according to claim 1, characterized in that the pump (1) is a vane pump. (Fig. 1 to Fig. 5).

4. Brake booster according to claim 1, characterized in that the pump (1) is a spindle pump. (Fig. 1 to Fig. 5).

5. brake power amplifier according to one of the preceding claims, characterized in that the electric motor is a brushless permanent magnet excited DC motor. (Fig. 1 to Fig. 5)

6. Brake booster according to one of the preceding claims, characterized in that a check valve (31, 32) is introduced in the input and / or output line (19 or 11), which prevents the backflow to the brake pressure transmitter. (Fig. 1 to Fig. 5)

7. Brake booster according to one of the preceding claims, characterized in that the valve device is formed from an analog controllable valve in slide or seat design.

(Fig. 1 to Fig. 5)

8. Brake booster according to one of the preceding claims, characterized in that the sensor device (VE; 3; 15,16) comprises pressure sensors (15,16) which sense the pressure (PV) in the pump outlet (11) and in the pump inlet (19) . (Fig. 1 to Fig. 6).

9. Brake booster according to one of the preceding claims, characterized in that the sensor device consists of an asymmetrical pressure compensator which is monitored with a position sensor and is adapted to the strengthening ratio (FIGS. 1 to 5).

10. Brake booster according to one of the preceding claims, characterized in that the 15

Components of the Bkv (8) are combined in one assembly. (Fig. 1 to Fig. 3, Fig. 5)

11. Brake booster according to one of the preceding claims, characterized in that between Bkv

(8) and wheel brakes (HL, VR) em ABS system (9) with the Ruckforderprmzip is interposed. (Fig. 1 to Fig. 5)

12. Brake booster according to claim 8, characterized in that the inlet pressure is increased disproportionately in the low pressure range (for a jumper function, rounded jumper). (Fig. 1

13. Brake booster according to claim 8, characterized in that the inlet pressure is increased disproportionately in the high pressure region to reduce the actuation forces. (Fig. 1 to Fig. 5).

14. Brake booster according to claim 8, characterized in that the input pressure is increased disproportionately with rapid brake pressure actuation (to achieve a brake assistant function). (Fig. 1 to Fig. 5)

15. Brake booster according to claim 8, characterized in that the brake pressure reduction takes place by opening the SO valve device. (Fig. 1 to Fig. 5)

16. Brake booster according to claim 11, characterized in that the output of the ABS pump is connected to the input of the pump. (Fig. 1 to Fig. 2)

17. Brake booster according to claim 11 or one of the following claims, characterized in that the ABS pump (35,36) is driven by the electric motor (2) of the Bkv (8). (Fig. 1 to Fig. 5)

18. Brake booster according to claim 11 or one of the following claims, characterized in that the ABS pump function can be taken over by the Bkv pump through a changeover valve (28) between the brake pressure transmitter (4) and the pump inlet (31). (Fig. 3 to Fig. 5)

19. Brake booster according to claim 11 or one of the following claims, characterized in that the low-pressure accumulators (23, 24) are dispensed with and their connection is connected to the container (25). (Fig. 22)

20. Brake booster according to claims 11 and 16 to 19, characterized in that the Bkv (8) and ABS

Unit (9) structurally m in an assembly (10) are merged. (Fig. 20 to Fig. 24)

21. Brake booster according to claim 8, characterized in that the sensor device (VB, 15.1, VG; Mu) and the pump are used for an ESP function. (Fig. 1 to Fig. 5)