JP4879437B2 - Vehicle brake device with pneumatic brake booster - Google Patents

Description

[0001]
The present invention relates to a vehicle brake device having a pneumatic brake booster having the characteristics described in the premise of claim 1.
[0002]
Such a braking device is known, for example, from EP 754 607, comprising effective means for detecting the maximum boost point of a pneumatic brake booster and an additional booster. Yes. This booster can be actuated by the detection means when the maximum boost point of the pneumatic brake booster is achieved. The means for detecting the maximum boost point comprises a pneumatic pressure switch and an electrical (contact) switch provided within the reaction disk. This electric switch has two opposing contacts provided on the reaction disk itself and a conductive path provided on the valve piston. The electrical evaluation unit detects the maximum boost point when both switches are operated, in other words, when both switches are electrically closed.
[0003]
This known device is expensive. This is because two switches and an evaluation device for the signals are provided. This not only increases the cost from the perspective of calibration of both switches, but also increases the cost of the hardware.
[0004]
Each cable is supplied from the brake booster to the electric control unit in a liquid-tight manner. Implementation of this system requires evaluation software that considers two switches. The problem cannot be solved by only one switch provided within the range of the junction disk. This is because the valve piston and the reaction disk come into contact with each other without necessarily achieving the maximum boost point each time the brake booster is operated.
[0005]
One pneumatic switch or sensor for sensing variable air pressure in the chamber (working chamber) is disadvantageous. This is because, for example, when the ventilation passage is blocked, the boosting is done very slowly or not at all. Subsequently, since the pneumatic switch is not operated, no error is recognized even though the driver requests an increase in boost. Therefore, it is not possible to generate a signal for the operation of the additional auxiliary power source.
[0006]
The object of the present invention is to provide a simplified and simultaneously improved braking device with a maximum boosting point detection device so as to output an appropriate signal even when the pneumatic brake boosting device does not supply the required boosting force. Is to provide.
[0007]
According to the features of the characterizing portion of claim 1, this object is provided with one switching means or sensor means, and this switching means or sensor means is a component of a brake booster that indicates the input force (Fe). Sensing the maximum proximity above the switching threshold, in particular between the input member and a part of the brake booster exhibiting a boost (Fv), in particular a movable wall or a connected part thereof, and Means are provided for detecting the maximum proximity duration, whereby a predetermined time including the maximum proximity duration of parts movable relative to each other is determinable, after a predetermined time has elapsed This is solved for the first time by issuing a signal indicating the maximum boost point.
[0008]
In another embodiment of the invention, proximity sensing is performed between the input member (valve piston) and the control casing that supports the movable wall.
[0009]
Furthermore, it is advantageous if a gap is provided in the area between the valve piston and the control casing, and this gap decreases as the boost of the brake booster increases. A completely closed gap or at least a minimized gap (ie, some contact between the valve piston and the control casing within the switch or sensor) is used to sense the maximum boost point. Accordingly, the operating element of the switch or sensor must be integrated into the control casing or valve piston.
[0010]
As will be appreciated, the electrical signal of the switch or sensor is supplied to the electrical control unit via a liquid tight cable connection. This control unit is preferably, for example, an electric control unit of an ABS control system having a driving dynamics control function or an electric control unit of a brake booster capable of external operation, preferably electromagnetic operation. Since such a control unit is already provided in almost all modern vehicles, the hardware costs for the control unit are further reduced.
[0011]
In order to save construction space, it is advantageous to use a very small sized macro switch.
[0012]
According to the characteristics of the other independent claims, the problem is that a switching means or sensor means is provided, between an output member showing the output force (Fa) and a movable wall showing the boost (Fv). By sensing the maximum proximity, the switching means or sensor means is solved by sensing the maximum boost based on the maximum deformation of the reaction element disposed between the output element (pressing rod) and the movable wall.
[0013]
According to the characteristics of the other independent claims, the problem is that a switching means or sensor means is provided, the maximum between the output member showing the output force (Fa) and the input member showing the input force (Fe). By sensing proximity, the switching means or sensor means is solved by sensing the maximum boost (Fv) based on the maximum deformation of the reaction element indirectly placed between the output element and the input element.
[0014]
An important effect of the present invention is that the maximum boost point is detected directly according to the present invention, i.e. it is not necessary to provide two switches or sensors, especially without the need for a pneumatic pressure sensor, the difference in force to be compared. It is to be detected directly in the range.
[0015]
Other advantageous embodiments of the invention emerge from the dependent claims in connection with the following description and drawings.
[0016]
The pneumatic brake booster shown in FIG. 5 is divided into a working chamber 3 and a negative pressure chamber 4 by a wall 2 that can move in the axial direction. The axially movable wall 2 is composed of a diaphragm plate 8 deeply drawn from a thin metal plate and a flexible diaphragm 18 in contact with the diaphragm plate. This diaphragm forms a rolling diaphragm (not shown) as a seal between the outer periphery of the diaphragm plate 8 and the booster casing 1.
[0017]
A control valve 12 operable by the operation rod 7 is accommodated in the control casing 5. The control casing is sealed and guided in the booster casing 1 and supports the movable wall 2. The control valve includes a first seal sheet 15 formed on the control casing 5, a second seal sheet 16 formed on the valve piston 9 connected to the operation rod 7, and cooperation with both the seal sheets 15 and 16. It consists of the valve body 10 to do. The valve body is pressed against the valve seats 15 and 16 by a valve spring 22 supported by the holding ring 21. The working chamber 3 can be connected to the negative pressure chamber 4 via a passage 28 extending to the side of the control casing 5.
[0018]
The braking force is transmitted to an operation piston of a master cylinder (not shown) of the brake device via a rubber elastic reaction disk 6 that contacts the control casing 5 and a pressing rod 14 having a head flange 23. This operation piston is attached to a negative pressure side end (not shown) of the brake vacuum booster. The force applied to the operating rod 7 is transmitted to the reaction disk 6 by the valve piston 9.
[0019]
The return spring 26 schematically shown in the figure is supported by the flange of the end wall on the suction side of the booster casing 1. This spring holds the movable wall 2 in the illustrated starting position. Furthermore, a second compression spring 27 is provided. The compression spring is disposed between the operating rod 7 and the support ring that contacts the holding ring 21 and holds the valve body 10 on the holding ring 21, and the force is applied to the valve piston 10 or the valve piston 9. The valve seat 16 is energized.
[0020]
In order to allow the working chamber 3 to communicate with the atmosphere when the control valve 12 is operated, a passage 29 extending in a substantially radial direction is formed in the control casing 5. At that time, the return movement of the valve piston 9 at the end of braking is limited by the transverse member 11. This transverse member is in contact with a sliding seal ring 13 which seals and guides the control casing 5 in the booster casing 1 in the illustrated release position of the vacuum brake booster.
[0021]
As further shown in FIG. 5, the valve element 10 includes a ring-shaped sealing surface that cooperates with both the sealing sheets 15 and 16. This sealing surface is reinforced by a metal reinforcing disk.
[0022]
During the braking operation, when the boosting is performed, the movable wall 2 supported by the control casing 5 slides toward the casing portion on the master cylinder side. Therefore, the position of the movable wall 2 represents the boost component generated by the booster. On the other hand, the position of the input member (operating rod 7) directly represents the driver's request. In the case of the solution of FIGS. 1 and 2, this relationship is used to sense the maximum boost point (control point) by simple means. In other words, the maximum proximity of the input member (operation rod 7) to the movable wall 2 is used to display the maximum boost point. Similarly, the maximum penetration length of the input member into the control casing 5 is used for display. This is advantageous in terms of space with respect to the required switch or sensor arrangement in the control casing 5.
[0023]
Also in the case of the solution of FIG. 1, the valve piston 9 provided at the end of the operating rod 7 is provided with a flange-like radial extension having a contact surface 30 (first reference surface) in its front range. ing. This contact surface is at a distance a with respect to the contact surface 31 (second reference surface) on the control casing side at the basic position. In this case, the distance a is chosen to be such that the gap disappears at the maximum boost point or at least significantly decreases so that the valve piston contact surface 30 is close to the control casing contact surface 31. In another embodiment of the invention, it is conceivable to provide an electrical button or switch 32 with operating elements. This button or switch is integrated in the control casing 5 and its operating element responds to the proximity of the valve piston 9 so that after proximity is achieved, a signal can be generated indicating the maximum boost point. In this case, the description or specific illustration of the method of arranging the switch or sensor is omitted intentionally. This is because various changes in this arrangement are known to the expert without departing from the invention. Furthermore, as an example and to some extent kinematically, the operating element of the switch or sensor may be integrated into the valve piston 9 and moved together with this valve piston. In this case, a signal is generated when the extended portion of the valve piston 9 contacts the contact surface on the control casing side together with the switch.
[0024]
For all solutions, it is basically the case that sensors, in particular Hall sensors, are preferred over electrical switches. The reason is that, for example, in the case of a sensor, an automatic calibration can be performed to determine a fixed device reference point in a non-operating state. This is done, for example, when the ignition device is switched on or every time the brake is operated, allowing a clear assignment of the switching state for a given booster operating state, independent of errors, and after years of driving and appropriate wear Even after. On the other hand, switches are susceptible to errors. This is because, in order to assign a predetermined switching state of the switch to a predetermined operating state of the brake booster, a built-in position that matches the error position must be guaranteed.
[0025]
For all solutions, a means of detecting the maximum proximity duration can be provided. Thereby, a signal notifying the maximum boost point is generated only after a predetermined time (maximum proximity exists within this time) has elapsed.
[0026]
This means can be implemented as a timed element in the electrical control unit, for example in the form of an algorithm. Thereby, additional hardware is not necessarily required. The duration can be, for example, 300 milliseconds. Thereby, the maximum boost signal is only generated when the above time-related signal is supplied to the switch or sensor.
[0027]
The following additional explanation is supplemented for the use of the holding member. In the case of the solutions of FIGS. 1, 2 and 4, the relative position of the input member 7 and the control casing 5 is important for evaluating whether the booster is in the maximum boost range. When the brake booster performs its maximum boost, it is desired that an additional boost is initiated, for example by an ABS pump. That is, the increase in the force acting on the master cylinder in the subsequent arrangement is no longer assisted by the brake booster, but must be additionally performed by the driver himself via the pedal. In this case, an additional braking force is required by the driver. This braking force cannot be provided by a booster. This is because the booster is performing maximum boost or has failed. As described above, this state can be detected when the gap between the control casing 5 and the input member 7 is below a predetermined value or when the input member is in contact with the control casing. Of course, if the clearance for normal driving in the brake booster is sufficiently small, the play of the pedal is correspondingly reduced. As a result, it is possible to shift from the normal operation to a state in which the input member abuts on the control casing, so that the pedal can directly act on the pressing rod of the master cylinder via the control casing. In this state, it is desirable to apply an additional braking force to provide the driver with assistance that cannot be obtained from the brake booster.
[0028]
Of course, if the clearance for normal operation is small, the small clearance will be eliminated by a sufficiently powerful operation of the pedal by the driver already during normal operation of the brake booster. Therefore, this allows the driver to slide the input member sufficiently with respect to the control casing by vigorous movement, and in this case, the input member is brought into contact therewith. During this movement, the valve for allowing atmospheric pressure to enter the working chamber of the booster is opened, so that the movable wall 2 and thus the control casing 5 follows the input member 5, thereby increasing the gap again. In contrast, in the maximum boost range of the booster, the input member remains in contact with the control casing while the driver requires additional braking force and acts on the input member accordingly. Thus, in the case of a small gap provided, whether the driver has acted strongly against the input member for a short time in the normal functional range of the brake booster or the brake booster is already within its maximum boost range. Whether or not can be distinguished by a timed element.
[0029]
However, if the gap is sufficiently large, time measurement can be omitted depending on circumstances. In this case, the driver does not contact the input member in the operating range of the brake booster that is outside the maximum boosting range. Because during normal braking, the driver's force is not sufficient to bring the input member into contact, and the control casing immediately follows the input member, thereby preventing contact during normal driving. It is. Only when the brake booster is in the maximum boost range, the driver can fully insert the input member into the reaction disk with the extremely large force required at that time. This insertion is performed until the input member comes into contact with the control casing. In other words, whether or not it is necessary to use a time measuring device in order to be able to distinguish between the normal range and the maximum boost range of the brake booster device depends on the size of the gap during normal operation.
[0030]
This is true even when the operation of the switch before the contact is important, not the achievement of the contact, in order to start acting the auxiliary force.
[0031]
A modified embodiment is apparent from FIG. In this case, matching parts and features are indicated by the same reference numbers. 2 differs from the solution of FIG. 1 in that proximity monitoring is not performed in the control casing 5 but between the contact member 35 and the end face 36 of the tubular collar of the control casing 5 outside the control casing. Yes. As can be appreciated, an integral stepped portion can, of course, be arranged on the operating rod 7 instead of a separate abutment piece 35. As described in the case of the solution of FIG. 1, in this case too, switches or sensors can be arranged in the control casing 5 or the valve piston 9 depending on the kinematic preference.
[0032]
FIG. 3 relates to another solution not related to FIGS. This solution is also based on the principle of directly sensing relative sliding on the side of the reaction disk 6 opposite the valve piston 9. In this case, like the above, the same reference numerals are used to indicate the same features.
[0033]
In this case, the relative sliding is sensed between the output member (pressing rod 14) and the movable wall 2, more precisely speaking, supporting the pressing rod 14 and the movable wall 2 and partially containing the reaction disk 6. This is performed with the control casing 5. Similar to the solution of FIGS. 1 and 2, the clearance shortening between the pressing rod 14 and the control casing 5 is used to sense the maximum boost point. This solution has the advantage that the built-in chamber of the electrical switch moves within the range of a brake booster in which a sufficient built-in chamber is provided on the basis of the negative pressure chamber 4. Therefore, there is no shortage of space in the control casing 5 based on the passage guidance.
[0034]
In the case of the solution of FIG. 4, sensing of the relative movement distance between the input member (valve piston 9) and the output member (pressing rod 14) is performed. This movement is based on deformation of the reaction disk 6 due to reaction force. In this case as well, a large braking force, and thus a large reaction force, reduces the thickness of the reaction disk 6, so that two reference points or reference planes of two different parts provided in the force transmission path. The shortening of the interval is used to detect the maximum boost point. In this case, as in the solution of FIGS. 1 and 2, it is necessary to monitor the time of maximum proximity between the input member and the output member that move relative to each other (duration). Thereby, only when the maximum relative sliding (proximity) lasts, for example, 300 milliseconds, the maximum boost point detection signal is issued. Thus, for example, the so-called depression of the pedal as a result of panic braking (which results in a large relative sliding in a short time) is clearly distinguished from a maximum boost point or a booster failure. In other words, the risk of malfunction is reduced even if only one switch or sensor is used.
[0035]
As will be appreciated, the necessary arithmetic operations are performed based on the algorithm of the electronic control unit. This is, of course, performed in a corresponding data processing unit.
[0036]
A switching contact may be inserted into the reaction element 6 as shown in FIG. In order to clarify this, FIG. 4 shows contacts 45 and 44 made of a conductive material. When these contacts come into contact with each other, a current circuit (not shown) is closed. This corresponds to the activation signal for the auxiliary force provided. The contacts can be formed in other forms. For example, the contact 45 can be integrally connected to the valve piston 9. The same is true for the contacts 44 for the output member 14. For this purpose, of course, the contacts should not be connected to each other by earth or ground when the switches 44, 45 are opened. Furthermore, there must be a free space between the contacts. Thereby, the contacts can contact each other.
[0037]
Furthermore, as understood for all solutions, the electrical signal of the switch or sensor can be supplied via a liquid-tight connection 40 to an electrical control unit not shown. This electric control unit can basically be arranged in any part of the vehicle, for example in the engine compartment or in the vehicle compartment. For connection to a so-called fly lead provided on the vehicle side or for direct connection to an electric control unit, a connection 40 on the booster side having a plug 41 can be provided. The arrangement of the connections 40 is shown schematically in FIG. In a variant, the cable can be provided in the area of the existing casing passage 42 (for cable or vacuum connection) and the cable itself can be guided through the chamber 4. In another variant, the cable is guided outside in the area of the casing lance piercing part and connected to the diaphragm inside the casing. In both cases, it is conceivable that at least a part of the connection 40 is injection-molded into a part of the control casing 5 (made of synthetic resin). In particular in the case of the solution with the contacts on the outside (FIG. 2), at least a part of the operating rod 7 and / or the valve piston 9 can additionally be provided as electrical conductors for signal transmission.
[0038]
Instead of guiding the contacts out of the casing of the brake booster 1 via the conductor 40, this can be done without a conductor by a radio link (telemetry) not shown. Instead of measuring the distance or travel distance, it is recommended that within the scope of the present invention, the travel distance difference is measured in order to detect the maximum boost range of the brake booster. That is, when the brake booster reaches its maximum boost range, the input member or valve piston is inserted into the reaction element until the valve piston contacts the control casing. From this point on, the overall force of the master cylinder opposes the driver's pedaling force. This causes a change in the movement of the pedal and thus the valve piston. Therefore, the difference in pedal displacement changes.
[0039]
The electric control unit is preferably an electric control unit of an ABS control system, in particular having a driving dynamics control function, or an electric control unit of a brake booster capable of external operation, in particular electromagnetic operation. Since such a control unit is already provided in most modern vehicles, the necessary hardware costs for the control unit are further reduced.
[Brief description of the drawings]
FIG. 1 is a partial sectional view showing the principle of the present invention based on a pneumatic brake booster, in which the upper half shows the basic position and the lower half shows the maximum boost point.
FIG. 2 is a diagram showing a second modification as in FIG.
FIG. 3 shows another principle solution as in FIG.
FIG. 4 is a diagram showing another solution similar to FIG.
FIG. 5 is a schematic partial cross-sectional view of a pneumatic brake booster to show electrical connections, particularly to vehicle electronics.

Claims (7)

An input member (7) for the pneumatic brake booster to be operated by the driver, an output member (pressing rod) (14), and a movable wall (2) supporting the reaction disk (6) at least partially And a means (32) for detecting the maximum boost point of the pneumatic brake booster (1), which operates other brake booster devices. In a vehicle brake device with a pneumatic brake booster (1), which can be used for
One switching means or sensor means (32) is provided, the switching means or sensor means, the input member of the input force the brake booster showing the (Fe) (1) (7), booster ( and sensing between the variable movement of the wall of the brake booster apparatus according to fv) (2) or parts connected thereto (5), the maximum proximity to above the switching threshold (a, z), this Means are provided for detecting the duration of the maximum proximity (a, z), whereby a signal indicating the maximum boost point is generated only after a predetermined time including the duration of the maximum proximity. Vehicle brake device.   The proximity (a, z) is sensed between the input member (7) (valve piston (9)) and a control casing supporting the movable wall (2). Brake device.   A gap (a) is provided in the range between the valve piston (9) and the control casing (5), and this gap can be reduced as the boost of the brake booster (1) increases, 3. Brake device according to claim 1 or 2, characterized in that a closed gap or at least a minimized gap (a) is used for sensing the maximum boost point. Brake device according to any one of claims 1-3, characterized in that the operating element of the switch or sensor is integrated in the control casing or the valve piston or reaction element. The brake device according to any one of claims 1 to 4 , wherein an electrical control unit is provided, and an electrical signal of a switch or a sensor is supplied to the control unit via a liquid-tight casing connection. . Control unit for detecting a maximum magnification power point is, any claim 1-5, characterized in that it is integrated into the casing of the control unit of the casing or electromagnetic operable brake booster of A BS control system The brake device as described in one. The brake device according to any one of claims 1 to 6 , further comprising a micro switch for sensing a maximum boost point.

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