DE19717639C2 - Fluidic automotive braking system - Google Patents

Description

The present invention relates to a fluidic Motor vehicle braking system that with a variety of Braking force control patterns can be used, and in particular to a brake fluid pressure control device for such fluidic motor vehicle braking system with Fluid pressure pumps is provided and is able to apply braking forces to control which are individually applied to respective bikes become.

A fluidic motor vehicle braking system with the features the preamble of claim 1 is from DE 37 34 903 A1 known. This braking system includes a pedal operated Master brake cylinder, which has a pressure line in which a Fluid flow restricting element is provided and which is in two pressure line branches branched, with one Wheel brake cylinder pair is connected. Opens into the pressure line A pump is connected via outlet lines one serving as an exhaust valve device electromagnetic open / close valve or electromagnetic 2/2-way valve is connected. The electromagnetic On / off valve connects the pair of wheel brake cylinders with the Suction side of the pump or separate it from it.

In addition, DE 44 45 512 A1 is a fluid one Motor vehicle braking system disclosed in which at the A 2/3-way valve is connected to the wheel brake cylinders is. These act as an intake / exhaust valve combination, i.e. H. in the pump pressure side is in a switch position Wheel brake cylinder applied while the exhaust pipe is shut off, and in the other position the  Brake circuit shut off while the outlet line is open to lower the pressure in the wheel brake cylinder.

One of the development goals for such brake fluid pressure Control devices is to reduce costs and build space save, d. H. relatively inexpensive electromagnetic valves as a pressure valve unit too use and the number of used to minimize electromagnetic valves without their Basic function for controlling the brake fluid pressure individually to adversely affect the respective vehicle wheel.

In US 5,441,336 (= JP 6-171487 A), for example Control device of an X-type arrangement disclosed on the JP 61-235254 A based. According to this control device is a brake fluid channel that has a master brake cylinder connects a brake cylinder of a front right wheel, provided with an electromagnetic valve to the To control fluid pressure. In the same way is also a another brake fluid channel that connects the master cylinder with one connects another brake cylinder for a front left wheel, with an electromagnetic valve of the same kind Mistake. When one of the electromagnetic valves is activated then a difference in fluid pressure between the generated two front wheels. The control device has the further an adjustment valve, which is designed to Responding to the pressure to take action. When the fluid pressure is applied to the front right vehicle wheel is applied, is less than the fluid pressure that is applied to the front left wheel is placed, then the adjustment valve actuated to increase the fluid pressure in a rear right wheel Taxes. In the opposite case, the adjustment valve actuated to increase the fluid pressure in a right left wheel Taxes. Looking to improve this conventional. Control device becomes a brake fluid pressure control device suggested that is able to control fluid pressure for everyone To control vehicle wheels. Although this recently  proposed device a maximum of four electromagnetic Open / close valves or 2/2-way valves are required not the adjustment valve mentioned above.

Since the facility, which in the US 5,441,336 is disclosed, no more than four electromagnetic on / off valves to control the Brake fluid pressure required for the respective wheels, it is relatively inexpensive. However, it is still extremely desirable the number of used further reduce electromagnetic valves. This means, it is advantageous if the brake fluid pressure control for the appropriate wheels are carried out in an appropriate manner, even in the case of a basic construction in which each Brake fluid pressure system with only one electromagnetic Valve is provided. This basic construction can be done with a or several electromagnetic valves corresponding to one certain vehicle types.

It is therefore an object of the present invention to provide a brake fluid pressure control device that Has fluid pressure pumps and is able to brake fluid pressure for each wheel individually under Use a minimum number of electro to control magnetic valves.

The task is performed by a fluid motor vehicle Braking system according to claim 1 solved that is particularly characterized in that each two wheel brake cylinders via an electromagnetic 3/2-way valve or a three-port / two-position Electromagnetic switching valve can be controlled individually are.

Further advantageous developments result from subclaims 2 and 3.

The present invention is illustrated below preferred embodiments with reference to the accompanying drawings described in more detail.

Fig. 1 is a diagram showing a brake fluid pressure control device according to a first embodiment of the present invention,

Fig. 2 is a diagram illustrating a brake fluid pressure control device according to a second execution of the present invention;

Fig. 3 is a diagram illustrating a brake fluid pressure control device according to a third execution of the present invention;

Fig. 4 is a diagram illustrating a brake fluid pressure control device according to a fourth execution of the present invention;

Fig. 5 is a diagram illustrating a brake fluid pressure control device according to a fifth execution of the present invention;

Fig. 6 is a diagram illustrating a brake fluid pressure control device according to a sixth execution of the present invention;

Fig. 7 is a diagram illustrating a brake fluid pressure control device according to a seventh execution of the present invention;

Fig. 8 is a diagram showing a brake fluid pressure control device according to an eighth embodiment of the present invention,

Fig. 9 is a diagram illustrating a brake fluid pressure control device according to a ninth execution of the present invention;

Fig. 10 is a diagram illustrating a brake fluid pressure control device according to a tenth execution of the present invention;

Fig. 11 is a diagram showing a brake fluid pressure control device according to an eleventh embodiment of the present invention,

Fig. 12 is a diagram showing a brake fluid pressure control device according to a twelfth embodiment of the present invention,

Fig. 13 is a diagram illustrating a brake fluid pressure control device according to a thirteenth execution of the present invention;

Fig. 14 is a diagram illustrating a brake fluid pressure control device according to a fourteenth execution of the present invention;

Fig. 15 is a diagram illustrating a brake fluid pressure control device according to a fifteenth execution of the present invention;

Fig. 16 is a diagram illustrating a brake fluid pressure control device according to a sixteenth execution of the present invention;

Fig. 17 is a diagram illustrating a brake fluid pressure control device according to a seventeenth execution of the present invention;

Fig. 18 is a diagram showing an example of a brake fluid pressure control device, which shows the same functional effect as embodiments of the invention, but is not the subject of the invention,

Fig. 19 is a timing chart showing a pattern for an anti-lock control which is executed by the brake fluid pressure control device according to the second embodiment of the present invention,

Fig. 20 is a time chart showing a different pattern of an anti-lock control which is executed by the brake fluid pressure control device according to the second embodiment of the present invention,

FIG. 21 is a timing chart showing still another pattern for an anti-skid control performed by the brake fluid pressure control device according to the second embodiment of the present invention, and

Fig. 22 is a sectional view showing a part of a device provided with dampers used for the front and rear assembly.

The following are the preferred embodiments the invention described with reference to the drawings.  

The Figs. 1 to 5 relate to a front wheel is surrounded trie (FF) vehicle with an anti-lock control function, whereas the FIGS. 6 through 9, a rear wheel driven (FR) driving generating relate to an anti-lock control function. Furthermore, FIGS . 10 to 17 relate to a vehicle with a slip control function, a vehicle stability control function and the like in addition to the anti-lock control function. That is, in the preferred examples as shown in Figs. 1 to 5 and Figs. 10 to 17 respectively, a diagonal arrangement is provided in which the left and right brake fluid pressure systems are constructed in the same manner. In this case, each brake fluid pressure system is provided with a three-port / two-position electromagnetic switching valve, which is basically designed to carry out an anti-lock control. On the other hand, the embodiment as shown in Figs. 6 to 9 is provided with a front and rear arrangement in which the front wheel side and rear wheel side brake fluid pressure systems are constructed in the same manner. In this case, the front wheel side brake fluid pressure system is provided with the above three-port / three-position electromagnetic switching valve.

The first embodiment of the present invention will now be described with reference to FIG. 1. As shown in FIG. 1, wheels FL, RR, RL, FR are each provided with wheel brake cylinders Wfl, Wrr, Wrl, Wfr, which are connected to a master cylinder 12 . It should be noted here that when viewed from a driver's seat, a front right wheel is designated by FR, a front left wheel is designated by FL, a right left wheel is designated by RL, and a rear right wheel is designated by RR is. The master cylinder 12 is a conventional tandem cylinder with first and second pressure chambers 12 a, 12 b. When a brake pedal 10 is operated, the Hauptzy cylinder 12 is driven by an amplifier 11 such that brake fluid to the first and second pressure chambers 12 a, 12 b is supplied from a reservoir 13 and pressurized. As a result, the brake fluid pressure is discharged through the master cylinder 12 . The brake booster 11 can be of the type of a vacuum booster or of the type of a fluid pressure booster.

As shown in FIG. 1, the wheels FL, RR, RL and FR are each provided with wheel speed sensors sfl, srr, srl, sfr, which are connected to an electronic control device 100 . Each wheel speed sensor is designed to enter the rotational speed of a respective wheel, ie to enter a corresponding number of pulse signals from the electronic control device 100 . The number of pulse signals is proportional to the speed of rotation of the wheel. The electronic control device 100 has a microcomputer (not shown) that performs a number of operations including anti-lock control. Referring to Figs. 1 to 5, in which the first to fifth For exemplary implementation of the present invention is shown in each case is drawn to the fact that left and right brake fluid pressure systems, which are in each drawing schematically Darge, are constructed in the same manner. Consequently, the following descriptions are given only with respect to those components which are denoted by odd numbers and are shown in the left half of the respective figure, without going into those components which are denoted by even numbers and shown in the respective right half of the figure are. A left component, which is denoted by a certain odd number, corresponds to a right th component, which is denoted by a respective even number, which is one greater than the respective odd number.

As shown in FIG. 1, the first fluid pressure chamber 12 a is connected to the wheel cylinders Wfl, Wrr via a main fluid pressure channel PO, which is divided into first and second fluid pressure channels P1, P2. The first and second Fluiddruckkä ne P1, P2 are schlüsse- to first and second terminals of a Dreian / two-position electromagnetic switching valve 31 is closed each fluid (hereinafter for simplicity only as a switching valve 31 hereinafter). The switching valve 31 is connected via a check valve 23 to an inlet of a fluid pressure pump 21 . The outlet of the fluid pressure pump 21 is connected via a check valve 25 , a damper D and a throttle 41 to the main fluid pressure channel PO and thereby to the first and second fluid pressure channels P1 and P2.

The fluid pressure pump 21 is operated by an electric motor 20 together with a fluid pressure pump 22 . The brake fluid is introduced into the inlet of the fluid pressure pump 21 , pressurized therein to a predetermined level and expelled through its outlet. The check valves 23 , 25 cause ken that the brake fluid, which is expelled from the fluid pressure pump 21 , constantly flows in a certain direction. A first throttle 43 is between a section that connects the switching valve 31 to the first fluid pressure channel P1 and the outlet of the fluid pressure pump 21 interposed, whereas a second throttle 45 between a connecting section that connects the switching valve to the second fluid pressure channel P3 and the Outlet of the fluid pressure pump 21 is interposed. In particular, the first fluid pressure channel P1 is provided with the first throttle 43 , whereas the second fluid pressure channel P2 is seen with the second throttle 45 . Proportional valves 51 , 52 of a known type are connected to the wheel cylinders Wrr, Wrl, respectively.

The right brake fluid pressure system is also constructed as described above. The fluid pressure pump 22 is driven by the electric motor 20 together with the fluid pressure pump 21 be. After the electric motor 20 is operated, the first and second fluid pressure pumps 21 , 22 are continuously driven so that the pressure of the discharged brake fluid is increased or decreased in accordance with the rotational speed of the electric motor 20th Accordingly, when a relatively small load is applied to one of the fluid pressure pumps (e.g., the pump 22 ), it is possible to increase the driving force on the other fluid pressure pump 21 , thereby improving the overall pressure loading performance.

The following is a description of how the brake pressure control device operates according to the first embodiment. In the normal braking operation, as shown in FIG. 1, each valve assumes its normal position with the electric motor 20 not actuated. If the brake pedal 20 is depressed further, the Hauptzylin 12 is operated by the amplifier 11 such that the brake fluid in the first and second pressure chambers 12 a, 12 b is pressurized. The fluid pressure to the respective brake fluid pressure systems is then delivered from the master cylinder 12 . The following description will now be limited to the brake fluid pressure system for simplification, which is shown in the left half of FIG. 1.

If it is determined during an anti-lock control of the wheel FL or RR that the wheel FL tends to lock, then a solenoid coil of the switching valve 31 assumes its first position and remains in a negative excitation. The switching valve 31 is fluidly separated from the second fluid pressure channel P2 and fluidly connected to the first fluid pressure channel P1.

At the same time, the electric motor 20 is operated to cause the fluid pressure pump 21 to start operating. As a result, the wheel cylinder Wfl is in a pressure reduction mode in which brake fluid contained therein is released to the fluid pressure pump 21 to achieve a reduction in pressure. When the wheel speed of the wheel FL is restored, the switching valve 31 is energized to assume its second position. When the switching valve 31 is in its second position, the wheel cylinder Wfl is in a pressure increase mode, in which the brake fluid pressure therein is increased by the master cylinder 12 . In this way, the switching valve 31 is discontinuously controlled such that the brake fluid pressure in the wheel cylinder Wfl is selectively increased or decreased. In this embodiment, in order to ensure a highly stable pressure reduction operation, the switching valve 31 is switched every time the electric motor 20 has completed a cycle, that is to say every time the fluid pressure pump 21 has completed a suction or discharge operation. In the following it will be described in detail how the electric motor 20 is operated. While the brake fluid is regulated in one of the wheel cylinders Wfl, Wrr, the other wheel cylinder Wrr, Wfl is prevented by the throttle 43 , 45 from being subjected to such brake fluid control.

In addition, the electric motor 20 is driven and subjected to power control to ensure that a constant current is obtained, thereby appropriately controlling the amount of brake fluid to be delivered by the fluid pressure pump 21 . As a result, the pressure increase gradient of the brake fluid in the wheel cylinder Wfl can be appropriately adjusted. If the drive source for the electric motor 20 is unable to supply a steady current, then the switching valve 31 is discontinuously controlled such that the brake fluid in the wheel cylinder Wfl is alternately increased and decreased to finally increase in a pulsed manner. In this way, the pressure increase gradient of the brake fluid is set. Such setting of the pressure increase gradient is referred to as a stepwise pressure increase mode or a pulse-wise pressure increase mode. Alternatively, it can also be referred to as a pump pressure increase mode, since in this mode the fluid pressure pump 21 also carries out a pressure increase operation. Similarly, the pressure decrease gradient of the brake fluid can be set in a pressure decrease mode.

If the fluid pressure in the master cylinder 12 becomes lower than the fluid pressure in the wheel cylinder Wfl after releasing the brake pedal 10 , then the brake fluid within the wheel cylinder Wfl is led through the throttle 43 back into the master cylinder 12 and then into the reservoir 13 .

As has been described so far, according to the first exemplary embodiment of the present invention, during the control of the fluid pressure in the wheel cylinder Wfl, the second fluid pressure channel P2 is fluid-separated upstream of the fluid pressure pump 21 . In addition, the throttle 43 prevents pressure fluctuations or changes in the brake fluid, which is expelled from the fluid pressure pump 21 , is transmitted to the wheel cylinder Wfl. As a result, the wheel RR is prevented from being affected by the braking force control of the wheel FL. In this way, the braking force control for a particular wheel can be performed independently of the other wheels. In the brake fluid pressure system shown in the left half of FIG. 1, the brake fluid pressure for the wheel cylinders Wfl, Wrr is individually controlled in accordance with the discontinuous control of the switching valve 31 and a resultant fluid pressure control mode. Similarly, in the brake fluid pressure system shown in the right half of FIG. 1, the wheels can be controlled individually.

As a result of this, a particularly suitable brake get power control.

According to the now following Fig. 2 shows a second exporting is approximately example of the present invention now be described. In this embodiment, a diagonal arrangement is also provided in which two brake pressure systems are built, as shown in FIG. 1. However, the second exemplary embodiment differs from the first exemplary embodiment in that the main fluid pressure channel PO is furthermore provided with a two-port / two-position open / close electromagnetic valve 33 (hereinafter referred to simply as an open / close valve 33 ). The wheel cylinders Wfl, Wrr are return channels via third and fourth fluid pressure P3, P4 respectively connected to the first pressure chamber 12a of the master cylinder 12th The fluid pressure channels or lines P3, P4 are each provided with third and fourth check valves 61 , 62 which allow the brake fluid to flow into the master cylinder 12 and prevent the same from flowing in the opposite direction. In this construction, when the brake pedal 10 is released, the fluid pressure in the wheel cylinders Wfl, Wrr is gently decreased in response to the fluid pressure decrease in the master cylinder 12 . The other components are constructed in the same way as in the first embodiment and are therefore not described in detail.

In the following it is described how the brake fluid pressure system works, which is shown in the left half of FIG. 2. In normal braking operation, each electromagnetic valve assumes its normal position, as shown in FIG. 2, with the electric motor 20 not actuated. If the brake pedal 20 is depressed further, then the fluid pressure from the first and second pressure chambers 12 a, 12 b of the master cylinder 12 through the on / off valve 33 , which he and the second throttles 43 , 45 and the first and second check valves 63 , 65 leads to the wheel brake cylinders Wfl, Wrr. In the following description, the anti-blocking control of the second embodiment is explained with reference to FIGS . 19 to 21. According to a control example shown in FIG. 19, the wheel cylinder Wfl is in a transition from the pressure reduction mode to the pressure maintenance mode, whereas the wheel cylinder Wrr is in the transition from the pressure maintenance mode to the pressure reduction mode. As shown in FIG. 19, a solenoid for the open / close valve 33 is energized at time T1 (indicated by "ON") when the electric motor 20 is activated (also indicated by "ON"). , At this point in time, the switching valve 31 remains negatively excited (indicated by "OFF"), assuming its first position according to FIG. 2. Accordingly, the brake fluid in the wheel cylinder of the Wfl is released to the fluid pressure pump 21 , so that the fluid pressure Pfl therein is reduced. On the other hand, since the second fluid pressure passage P2 leading to the wheel cylinder Wrr is not fluidly connected to the switching valve 31 or the on / off valve 33 , the fluid pressure Prr is kept in the wheel cylinder Wrr without being reduced. A pulse is output every time the fluid pressure pump 21 completes a cycle, that is, each time the fluid pressure pump 21 completes its suction or discharge operation. In response to such a pulse output (indicated by "ON" in Fig. 19), the switching valve 31 is switched to either the first ("OFF") or the second "ON" position. When the fluid pressure pump changes from the suction mode to the discharge mode at time T2, the fluid pressure Pfl is held in the wheel cylinder Wfl. When the fluid pressure pump 21 completes a cycle to enter the suction mode again at time T3, the switching valve 31 is switched to the second position, whereby the decrease in the fluid pressure Prr in the wheel cylinder Wrr is started. Conversely, the fluid pressure Pfl remains unchanged in the wheel cylinder Wrr. Although the switching valve 31 is likely to be switched to the first position in principle, it may still remain in the second position according to the control example as shown in FIG. 19. Accordingly, the fluid pressure in the wheel cylinder Pfl is in the holding mode, whereas the fluid pressure in the wheel cylinder Prr is in the pressure reducing mode.

According to a further control example, which is shown in FIG. 20, the wheel cylinder Wfl is in the pressure reduction mode, whereas the wheel cylinder Wrr is in the (gradual) pressure increase mode. In this case, the solenoids for the on / off valve 33 and the switching valve 31 remain energized negatively even after the time t1 when the electric motor 20 is activated. That is, the on / off valve 33 remains in its open position while the switching valve 31 remains in the first position. Consequently, when the electric motor 20 starts rotating at time t1, the fluid pressure Pfl in the wheel cylinder Wfl is alternately decreased and increased to eventually increase, while the fluid pressure Prr in the wheel cylinder Wrr is alternately gradually and normally increased to finally be raised. During the period between t1 and t2, the brake fluid in the wheel cylinder Wfl is directed to the fluid pressure pump 21 , so that a substantial part of the brake fluid flowing through the on / off valve 33 is delivered to the wheel cylinder Wfl ge. As a result, the pressure increase gradient of the fluid pressure Prr becomes relatively small during this period. On the other hand, during the period between T2 and T3, the brake fluid in the wheel cylinder Wfl is not released to the fluid pressure pump 21 , so that the brake fluid flowing through the on / off valve 33 is distributed substantially uniformly to the wheel cylinders Wfl, Wrr , As a result, the pressure increase gradient of the fluid pressure Prr becomes relatively large during this period. For this reason, the pressure increase gradient of the fluid pressure Prr between T1 and T2 is smaller than between T2 and T3.

According to a further control example, as is shown in FIG. 21, both wheel cylinders Wfl, Wrr are in the pressure increase mode, in which the electric motor 20 remains activated. The on / off valve 33 remains in its most position, whereas the solenoid for the switching valve 31 is alternately positively and negatively excited, so that the switching valve 31 is alternately switched to the first and second positions. As a result, the fluid pressure Pfl and the fluid pressure Prr are alternately increased and decreased to finally increase.

The pressure increase gradient or the pressure decrease gradient can be arbitrarily set by adjusting the rotational speed of the electric motor 20 using the PWM control described above, for example. Alternatively, the gradients can be set arbitrarily by adjusting the switching period (switching ratio) during which the open / close valve 33 and the switching valve 31 are excited positively or negatively. In addition, the entire control is performed based on the fluid pressure output from the fluid pressure pumps 21 , 22 while they are each fluid-separated from the master cylinder 12 by the on / off valves 33 , 34 . Accordingly, the appearance of a so-called "kick-back" during an anti-lock control is prevented. Furthermore, unlike the conventional technology, no distribution operation noise is caused.

In the following, a third embodiment of the prior invention is described with reference to FIG. 3, in which the on / off valves 33 , 34 of the second exemplary embodiment are replaced by throttles 47 , 48 . The throttles 47 , 48 prevent pressure fluctuations or changes from being transmitted to the master cylinder 12 or further onto the brake pedal 10 during the anti-lock control.

In the following, a fourth embodiment of the present invention is described with reference to FIG. 4, in which the throttles 43 to 46 of the first embodiment are set by mechanically constructed pressure response valves 91 to 94 , each of which has a throttle installed therein. The pressure response valves 91 to 94 normally assume their first positions, as shown in FIG. 4, in order to thereby enable relatively large fluid channel cross sections. On the other hand, if they assume their second positions, the channel cross-sections or areas are reduced by the above-mentioned restrictors which are installed in the respective pressure response valves 91 to 94 , whereby the same effect is achieved as in the third exemplary embodiment according to FIG . 3. This Druckan speaking valves 91 to 94 are in accordance with a relationship between the supplied from the dampers D, D the brake fluid pressure, which pressure pump towards the outlet of the fluid 21, 22 are provided, and the brake fluid pressure in the wheel cylinders Wfl, Wrr, Wrl and Wfr switched. If, for example, the former is larger than the latter, then who switched the pressure response valves 91 to 94 from the first positions to the second positions.

In the following, a fifth embodiment of the prior invention is described with reference to FIG. 5, in which the throttles 43 to 46 of the first embodiment by two connections / two-position open / close electromagnetic valves (open / close valves) 35 to 38 and check valves 61 , 62 , 67 , 68 are each replaced. The check valves 61 , 62 , 67 , 68 operate in substantially the same manner as those shown in Fig. 2. During the control of the fluid pressure in the wheel cylinders Wfl, Wrr, Wrl and Wfr, the on / off valves 35 to 38 are respectively controls ge substantially in the same manner as the on / off valve 33 , which is shown in FIG. 2 ge.

In the following, with reference to FIGS . 6 to 9, which shows a rear-wheel-drive vehicle equipped with a brake fluid pressure control device according to the present invention, it is shown that the sixth to ninth exemplary embodiments of the invention are described. According to the sixth embodiment, the wheel RR shown in FIG. 1 is replaced by the wheel FR shown in the left half of FIG. 6, making it unnecessary to use the proportional valve 51 . As shown in the right half of FIG. 6, on the other hand, the wheel cylinders Wrr, Wrl are each connected to the fluid pressure channel P4, which is connected to the proportional valve 52 and the two-port / two-position open / close valve (open / close valve). 34 is provided. The inlet of the fluid pressure pump 22 is connected via a throttle 82 to a section of the fluid pressure channel P4 between the open / close valve 34 and the proportional valve 52 . Accordingly, according to the control operation performed by the electronic control device 100 in this embodiment, the front wheel brake fluid pressure system is controlled in substantially the same manner as the system in the left half of FIG. 1, whereas the rear wheel brake fluid pressure system is controlled in the same manner Is controlled like a conventional antiblocking control device in which the on / off valve 34 is continuously controlled.

According to the seventh exemplary embodiment, which is shown in FIG. 7, the on / off valve 34 for the rear wheel-side brake fluid pressure system according to FIG. 6 is replaced by the throttle 84 and the throttle 82 according to FIG. 6 is by a two-port connection / Two-position open / close electromagnetic valve 96 replaced. The front wheel side brake fluid pressure system is constructed in the same manner as shown in FIG. 6. Accordingly, the rear wheel side system is controlled in the same manner as a conventional anti-lock control device in which the on-off valve 96 is intermittently activated.

According to the eighth and ninth exemplary embodiment according to FIGS . 8 and 9, the front wheel-side brake fluid pressure system is basically constructed in the same way as shown in FIG. 2, with the exception that the proportional valve 51 is dispensed with. In the rear wheel side brake fluid pressure system according to FIG. 8, the throttle 82 according to FIG. 6 is replaced by the two-port / two-position open / close electromagnetic valve 96 . The rear wheel side Sy stem of FIG. 9 is constructed in the same manner as in the Fig. 6 is shown. In the eighth and ninth exemplary embodiments, the open / close valves 33 , 34 , 96 are necessary in addition to the switching valve 31 . By appropriately adding on / off valves and / or throttles to a basic structure provided with the switching valve 31 , it is possible to easily set a desired control pattern. According to the tenth and seventeenth embodiments, as they are shown each in FIGS . 10 to 17, the brake fluid pressure control device is constructed such that it can perform a slip control or the like in addition to the anti-blocking control. In these Ausführungsbeispie len between the pressure chambers 12 a, 12 b of the master cylinder 12 and the throttles 41 , 42 two connections / two-position on / off electromagnetic valves (on / off valves) 71 , 72 , pressure relief valves 73 , 74 and check valves 75 , 76 inserted between each. The open / close valves 71 , 72 normally assume their normal positions according to FIGS. 10 to 17. While the brake pedal 10 is not actuated, for example, at the time of a slip control, and when the wheel brake cylinders Wfl, Wrr, Wfr, Wrl are acted upon by a brake fluid pressure by means of the fluid pressure pumps 21 , 22 , then lenoids of the open / close valves 71 , 72 are excited to ensure that the on / off valves 71 , 72 take the closed positions. When the brake fluid pressure output from the fluid pressure pumps 21 , 22 exceeds a predetermined value, the brake fluid is returned to the master cylinder 12 through the relief valves 73 , 74 , thereby maintaining the downstream fluid pressure at the predetermined value. The check valves 75 , 76 allow the brake fluid to flow from the master cylinder 12 to the wheel cylinders Wfl, Wrr, Wfr, Wrl and prevent the same from flowing in the opposite direction. When the brake pedal 10 is operated during the fluid pressure control, the wheel cylinders are pressurized with a brake fluid pressure through the check valves 75 , 76 , thereby allowing the brake pedal 10 to be depressed further. According to the tenth exemplary embodiment according to FIG. 10, in addition to the components according to FIG. 1, the on / off valves 71 , 72 are provided in order to carry out a slip control. That is, if the wheels FL, FR start to slip during their acceleration, the on / off valves 71 , 72 are closed, the electric motor 20 is activated and the switching valves 31 , 32 are controlled discontinuously. The wheels FL, FR are hereby appropriately prevented from slipping further.

According to the eleventh and twelfth exemplary embodiments, as shown in FIGS. 11 and 12, in addition to the components according to FIGS. 4 and 5, the above-mentioned open / close valves 71 , 72 are provided in order to control slip, a Brake force distribution control and a brake steering control to perform. In addition, according to the thirteenth embodiment, as shown in FIG. 13, the front wheel side system is constructed in the same manner as that in FIG. 1, whereas the rear wheel side system is constructed in the same manner as that according to FIG. 5. In addition, the brake fluid pressure control device 13 is shown in FIG. with the open / close valves 71, provided 72nd

When the above brake force distribution control is executed during braking operation, then the Ver Ratio of braking forces applied to the rear wheels and those who are attached to the front wheels in  suitably controlled to the stability of the vehicle guarantee. If the above brake steering control is executed, for example when the vehicle turns, then either becomes an oversteer button denz suppression control or an understeering tendency Suppression control executed to the stability as well to maintain the directional stability of the vehicle. In that case an override control to prevent the driving excessively oversteer when the vehicle is cornering, braking forces are applied to a front wheel, which radi al outwards with reference to the center of the curve of the vehicle pla is adorned, causing the vehicle to be pushed radially outward becomes. In the case of understeer control to prevent tion that the vehicle understeers excessively when driving If a corner turns, braking forces are applied to a front wheel created which radial outwards with reference to the curve with telpunkt of the vehicle is placed and also both rear Wheels, causing the vehicle to be pushed radially inward and the speed is reduced.

According to the fourteenth to sixteenth embodiments, as shown in FIGS. 14 to 16, the on / off valves 71 , 72 are replaced by three ports / two-position switching valves (switching valves) 77 , 78 , which are provided for one 14, 15 and 16 are constructed in the same manner as those in FIGS. 13, 11 and 12, except that the switching valves 77 , 78th . The brake fluid pressure control device shown in FIGS . 14, 15 and 16 instead of the on / off valves 71 , 72 are easily seen.

According to the seventeenth embodiment, which is shown in FIG. 17, the switching valves 77 , 78 according to FIG. 16 by the on / off valves 71 , 72 , the check valves 97 , 98 and the throttles 97 a, 98 a, respectively replaced. The check valves 97 , 98 and the throttles 97 a, 98 a work in cooperation with the on / off valves 71 , 72 , which are controlled to selectively open or close, whereby essentially the same effect is achieved , as in the switching valve of the switching valves 77 , 78 .

FIG. 18 shows, by way of illustration, an example not falling under the invention, in which the switching valves 31 , 32 according to FIG. 1 by two electromagnetic 2/2-way valves or on / off valves 301 , 302 , On / off valves 303 , 304 and check valves 305 , 308 are replaced. The open / close valves 303 , 304 , which are normally closed, are selectively opened or closed in accordance with a difference in pressure between the upstream and downstream sides of the respective open / close valves 301 , 302 . The open / close valves 301 , 302 , the open / close valves 303 , 304 and the check valves 305 bsi 308 are provided in order to achieve essentially the same effect as the switching valves 31 , 32 . In this case, the rear wheel system is provided with the on / off valves 303 , 304 . If the on / off valves 301 , 302 are closed, for example upon activation of the fluid pressure pumps 21 , 22 , then a difference in pressure between the upstream and downstream sides of the respective on / off valves 301 , 302 is generated. The open / close valves 303 , 304 are then switched from the closed position to the open position. The check valves 305 , 308 prevent pressure fluctuations at the inlet of the fluid pressure pumps 21 , 22 to perform a gentle pressure reducing operation.

FIG. 22 shows an example of a device with two dampers D, D corresponding to the front and rear arrangement, as shown in FIGS. 6 to 9. In the front and rear arrangement, since the amount of brake fluid to be discharged from one of the fluid pressure pumps 21 , 22 is different from the amount to be discharged from the other, it is desirable that the two pumps 21 , 22 22 are different from each other in terms of their capacities. Consequently, an additional damper is generally provided in addition to the front-wheel damper D, which inevitably requires a channel for fluid communication between the two dampers, and increases the total number of parts. Taking this background into consideration, the device according to FIG. 22 is provided with a front-wheel-side damper D1 and a rear-wheel-side damper D2, which differ in terms of their capacity from one another. The dampers D1, D2 consist of pistons P1, P2, springs S1, S2 and cylinder chambers C1, C2. In this construction, the pistons P1, P2 are each biased by the springs S1, S2. The cylinders of C1, C2, although a diameter, are different from each other with respect to their axial dimensions and are built up to be in fluid communication with the outlets of the fluid pressure pumps 21 and 22, respectively. A piston 21 p for the fluid pressure pump 21 has a larger diameter than a piston 22 p for the fluid pressure pump 22 , both pumps 21 , 22 being connected to the electric motor 20 . In addition, the axial dimension of the cylinder chamber C1 is larger than that of the cylinder chamber C2, making the capacity of the former larger than that of the latter.

The present invention as described so far has advantages in the following points.

Since according to a first aspect of the present invention the brake fluid pressure device with a minimum possible on number of electromagnetic valves, it is considerably inexpensive. Although a minimally possible approach number of electromagnetic valves is provided, can nevertheless the fluid pressure is more suitable for the respective wheels Be controlled individually. In addition, this Setup either with a diagonal arrangement or one Front and rear arrangement can be applied.  

According to a second aspect of the present invention, the Three-port / three-position electromagnetic switching valve either the first position or the second position switches, every time the fluid pressure pump a Zy closes. During a given wheel a fluid pressure the other wheels are consequently subjected to control protected from being influenced by such a control the. Overall, it is therefore possible to use a suitable fluid pressure control.

According to a third aspect of the present invention the occurrence of the so-called "kick-back" prevented by the first and second chokes, which on the upstream side of the three ports / three position eclectromagnetic switching valve are provided.

According to a fourth aspect of the present invention in addition, first to fourth check valves additionally provided for the above components. While a certain wheel is subjected to fluid pressure control, the other wheels are therefore protected from such to be influenced by a controller, so overall it is possible to perform the fluid pressure control in a suitable manner ren.

Claims (3)

1. Fluidic motor vehicle braking system, with
a pedal-operated master brake cylinder (12) having at least one working chamber (12 a), which is connected via a brake circuit (P0, P1, P2) with two wheel brake cylinders (Wfl, Wrr), one to the brake circuit (P0, P1, P2) Fluid volume flow restricting device is inserted and wherein the brake circuit (P0, P1, P2) consists of a pressure line (P0) branching into a first (P1) and a second (P2) pressure line branch, and
a pressure pump ( 21 ) which opens into the pressure line (P0) on the pressure side and is connected to the pressure line branches (P1, P2) on the suction side via outlet lines with the interposition of an outlet valve device between the device restricting the fluid volume flow and the wheel brake cylinders (Wfl, Wrr),
characterized in that
the device throttling the fluid volume flow consists of a throttle element ( 43 , 45 ; 91 , 93 ; 35 , 37 ) provided in the first (P1) and second (P2) pressure line branch, and that
the outlet valve device is an electromagnetically switchable 3/2-way valve ( 31 ), which has two inlet connections, each connected to a wheel brake cylinder (Wfl; Wrr), and an outlet connection connected to the suction side of the pressure pump ( 21 ), the 3/2-way valve ( 31 ) in its one position connects one wheel brake cylinder (Wfl) and in its other position the other wheel brake cylinder (Wrr) to the suction side of the pressure pump ( 21 ), while the other wheel brake cylinder is disconnected. 2. Brake system according to claim 1, characterized in that the 3/2-way valve ( 31 ) each time the pressure pump ( 21 ) completes a cycle, ie a suction or exhaust process, either in the first position or second position is switchable. 3. Brake system according to claim 1, characterized in that

• - Each of the two pressure line branches (P1, P2) has a check valve ( 63 ; 65 ) blocking in the direction of the master brake cylinder ( 12 ), each between the throttle element ( 43 ; 45 ) and the junction point of the respective outlet line with the associated pressure line branch (P1; P2 ) is arranged,
• - To each pressure line branch (P1, P2) between the check valve ( 63 ; 65 ) and the wheel brake cylinder (Wfl; Wrr) a relief line (P3, P4) leading to the master brake cylinder ( 12 ) is connected, in which a direction towards the master brake cylinder ( 12 ) Another check valve ( 61 , 67 ) is inserted.