JP2019119340A - Brake device and on-vehicle brake system - Google Patents

Abstract

To prevent generation of a braking force from being lost due to failure or breakage of a power source, and to suppress an adverse effect associated with magnetization of a magnetic circuit.SOLUTION: By using switching devices Q1 to Q4 connected in a bridge shape to an electromagnet coil 16, power source power of a plurality of power sources 21, 22 is selectively supplied to the electromagnet coil 16 to cause currents i1, i2 having different directions to selectively flow. Even when an abnormality such as a failure or voltage drop occurs in one of the plurality of power sources 21, 22, a necessary braking force can be secured by automatically selecting a power source of a normal system by a brake ECU30. By switching the directions of the currents i1, i2 flowing through the electromagnet coil 16, it is possible to suppress magnetization due to an influence of a DC magnetic field and to prevent generation of the braking force at the time of non-energization. It is also possible to demagnetize a permanent magnet generated by the magnetization and to facilitate diagnosis of each part of a circuit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a brake device that can be used for braking a vehicle or the like and an in-vehicle braking system.

  For example, Patent Document 1 shows the technology of a brake device for a vehicle using MR fluid. That is, the rotating side disc and the stationary side disc are alternately arranged, and the composite material formed by impregnating the porous member with the MR fluid is supported and fixed on the side face of the stationary side disc. Then, at the time of braking, the gap between the rotating disk and the composite material is made zero by the drive device. Then, in this state, a current is supplied to the electromagnetic coil constituting the applying device to form a magnetic circuit in the casing functioning as a yoke. Then, by applying a magnetic field to the MR fluid in the porous member, the apparent viscosity of the MR fluid is changed to impart rotational resistance to the rotating disk.

  Further, the vehicle control device of Patent Document 2 shows a technology for generating a driving force of a vehicle using an electric motor and performing control to short circuit coil terminals of the electric motor to generate a braking force. There is. In addition, in order to generate three-phase AC power necessary for driving the electric motor, an inverter including a switching circuit connected in a bridge shape is used.

JP, 2017-116014, A JP, 2017-184338, A

  For example, when driving an electric motor, it is necessary to control the direction and magnitude of the current flowing through the exciting coil of the electric motor, so using a switching circuit connected in a bridge shape as in Patent Document 2 It controls the energization of the exciting coil. On the other hand, the braking force of the brake device using the MR fluid as in Patent Document 1 is not affected by the direction of the magnetic field generated by the electric coil. Therefore, in the case of such a brake device, an operation of switching the energization direction of the electric coil is not performed.

  On the other hand, in the case of a brake device as disclosed in Patent Document 1, power supply power is required to generate a braking force. However, in the case of a brake device for a vehicle, it is necessary to take into consideration the possibility that power supply power supplied from an on-vehicle battery or the like may be interrupted due to any failure or malfunction. That is, it is necessary to prevent the situation that the brake device can not generate the braking force even if the supply of the power supply is stopped.

  Moreover, in the case of a brake device like patent document 1, there exists a possibility that the yoke of a magnetic circuit, etc. may be magnetized by the influence of the magnetic field which an electric coil generate | occur | produces. And, even if the electric coil is not energized when the yoke or the like is magnetized, the MR fluid drags between the rotating side and the stationary side due to the influence of the magnetism of the permanent magnet generated by the magnetization. Become. That is, even if the brake is turned off, the braking force can not be completely released.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to prevent generation of braking force from being lost due to failure or failure of a power supply, and to accompany magnetization of a magnetic circuit. An object of the present invention is to provide a brake device and an on-vehicle braking system capable of suppressing an adverse effect.

In order to achieve the above-mentioned object, a brake device and an in-vehicle braking system according to the present invention are characterized by the following (1) to (5).
(1) A function of filling the space between the fixed member, the movable member disposed at the position facing the fixed member, and the space between the movable member and the fixed member, and changing the viscoelasticity according to the application of the magnetic field A brake device comprising: a reactive fluid; and a magnetic field generator for applying a magnetic field to the functional fluid,
The magnetic field generator is
At least one electrical coil,
A first switch circuit connected between an output of the first power supply unit and the electric coil to control energization of current in a first direction of the electric coil;
A second switch circuit connected between an output of a second power supply unit and the electric coil to control energization of current in a second direction of the electric coil;
An electronic control unit that selectively controls the first switch circuit and the second switch circuit in accordance with a predetermined braking instruction;
A brake device comprising:

  According to the brake device of the configuration of (1), for example, the second power supply unit outputs when the first power supply unit fails or its output voltage drops abnormally or when the first switch circuit breaks down. Since the electric coil can be energized using the power supply power, the necessary braking force can be secured. Also, even if the second power supply unit fails or its output voltage drops abnormally, or the second switch circuit fails, the electric coil can be energized using the power supply output from the first power supply unit. , You can secure the necessary braking force. Further, when the electronic control unit selectively switches the first switch circuit and the second switch circuit, current flows in different directions in the electric coil, and the direction of the magnetic field also changes. Therefore, it is possible to suppress the magnetization of the magnetic circuit, and it is also possible to provide a demagnetizing function.

(2) The first switch circuit controls a connection between the output of the first power supply unit and the first terminal of the electric coil, and a low potential common to the second terminal of the electric coil. And a second switch to control connection with the line,
The second switch circuit includes a third switch for controlling connection between the output of the second power supply unit and the second terminal of the electric coil, the first terminal of the electric coil, and the low potential line And a fourth switch that controls connection of the
The electronic control unit allows connection of the first switch and the second switch when the third switch and the fourth switch are both off, and when the first switch and the second switch are both off. Allow connection of a third switch and the fourth switch,
The brake device according to the above (1), characterized in that

  According to the brake device of the configuration of (2), current can flow in the direction from the first terminal of the electric coil to the second terminal by turning on both the first switch and the second switch. In addition, by turning on both the third switch and the fourth switch, current can flow in the direction from the second terminal of the electrical coil to the first terminal. In addition, under the control of the electronic control unit, a short circuit between each output of the first power supply unit and the second power supply unit and the low potential line can be prevented.

(3) The electronic control unit monitors the state of at least a part of the first switch circuit, the second switch circuit, the first power supply unit, and the second power supply unit, and detects a failure or abnormality Automatically switching the selection state of the first switch circuit and the second switch circuit,
The brake apparatus as described in said (1) or (2) characterized by the above-mentioned.

  According to the brake device of the above configuration (3), even if a failure or abnormality occurs in any of the first switch circuit, the second switch circuit, the first power supply unit, and the second power supply unit, Since the control unit automatically switches the selection state of the first switch circuit and the second switch circuit, the braking force can be secured using a normal circuit.

(4) The electronic control unit periodically and alternately selects the first switch circuit and the second switch circuit when the predetermined condition is satisfied, and switches the conduction state of the electric coil.
The brake device according to any one of the above (1) to (3), characterized in that

  According to the brake device of the configuration of (4), the direction of the magnetic field generated by the electric coil is periodically switched by alternately selecting the first switch circuit and the second switch circuit. This enables abnormality detection of both the first switch circuit and the second switch circuit. Further, abnormality detection of the outputs of the first power supply unit and the second power supply unit is also possible. Furthermore, since the direction of the generated magnetic field is periodically switched, the magnetization of the magnetic circuit is less likely to occur.

(5) A vehicle-mounted braking system comprising a plurality of braking devices according to any one of (1) to (4), wherein the braking states of a plurality of wheels mounted on a vehicle are controlled by the independent braking devices.
The electronic control unit simultaneously supplies common power to the brake devices of the plurality of wheels from the output of the selected power supply system among the first power supply unit and the second power supply unit.
An on-board braking system characterized by

  According to the on-vehicle braking system configured as described in (5) above, even if the power supply voltages output from the first power supply unit and the second power supply unit are different from each other, common power is supplied to the brake devices of the plurality of wheels. Since supply is simultaneously performed, bias does not occur in the braking torque applied to a plurality of wheels. Therefore, stable braking operation of the vehicle is possible.

  According to the brake device and the on-vehicle braking system of the present invention, it is possible to prevent the generation of the braking force from being lost due to the failure or failure of the power supply, and to suppress the adverse effects associated with the magnetization of the magnetic circuit. become.

  The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the modes for carrying out the invention described below (hereinafter referred to as "embodiments") with reference to the attached drawings. .

FIGS. 1 (a) and 1 (b) are longitudinal sectional views showing the main components related to the operation principle of a braking mechanism using MR fluid, in which the currents flow in different directions. Represent. FIG. 2 is a block diagram showing a configuration example of an electronic circuit for controlling an electromagnet coil of the braking mechanism shown in FIGS. 1 (a) and 1 (b). FIGS. 3 (a) and 3 (b) are block diagrams showing major components of a system for controlling four braking mechanisms mounted on a vehicle, in which current flows in different directions. . FIG. 4 is a flowchart showing an operation example-1 of a system that controls four braking mechanisms. FIG. 5 is a flowchart showing an operation example-2 of a system that controls four braking mechanisms. FIG. 6 is a flowchart showing an operation example-3 of a system that controls four braking mechanisms.

  Specific embodiments of the present invention are described below with reference to the figures.

<Basic structure and principle of operation>
The major components related to the operating principle of the braking mechanism 10 using MR fluid are shown in FIGS. 1 (a) and 1 (b). FIGS. 1A and 1B show states in which current flows in different directions.

  The braking mechanism 10 shown in FIGS. 1 (a) and 1 (b) can be used, for example, to brake the rotation of each wheel of the vehicle. The rotating body 12 of the braking mechanism 10 has, for example, a disk rotor 12a connected to each wheel of the vehicle, and rotates together with the wheel. The fixing member 11 is formed in an annular shape so as to surround the outer side of the rotating body 12, and has a plate-like electromagnet yoke 11a. The electromagnet yoke 11a and the disk rotor 12a face each other in a surface, and a gap is formed between these surfaces. The fixing member 11 is fixed to, for example, a vehicle body. 1 (a) and 1 (b) show a cross section of the upper half with respect to the rotation axis (not shown).

  An MR fluid (Magneto Rheological Fluid) 14 is filled in a space 13 including a gap between the electromagnet yoke 11a and the disk rotor 12a. The MR fluid 14 is, for example, one in which a large number of ferromagnetic particles such as iron powder are dispersed in a liquid such as oil. The particle size of the ferromagnetic particles is about several [μm]. The space 13 is formed inside a housing (not shown) and can maintain the MR fluid 14 in a sealed state.

  The electromagnet core 15 made of a ferromagnetic material such as iron is integrally formed with the fixing member 11, for example. An electromagnet coil (electric coil) 16 is wound on the outside of the electromagnet core 15. When a current flows in the forward direction through the electromagnet coil 16, a magnetic field 17F in the direction shown in FIG. 1A is generated. The magnetic field 17F forms a magnetic path that passes through a magnetic circuit including the electromagnet core 15, the electromagnet yoke 11a, the MR fluid 14, and the disk rotor 12a. In addition, when current flows in the reverse direction to the electromagnet coil 16, a magnetic field 17R in the direction shown in FIG. 1B is generated. The magnetic field 17R also forms a magnetic path that passes through a magnetic circuit including the electromagnet core 15, the electromagnet yoke 11a, the MR fluid 14, and the disk rotor 12a.

  Therefore, in the state of FIG. 1 (a) or FIG. 1 (b), a relatively strong magnetic field is applied to the MR fluid 14 present in the gap between the facing surfaces of the electromagnet yoke 11a and the disk rotor 12a. Can.

  When no magnetic field is applied from the outside, the ferromagnetic particles in the MR fluid 14 exist in a dispersed state. Therefore, in this state, no braking force is generated with respect to the rotation operation of the disk rotor 12a.

  On the other hand, when a magnetic field is applied from the outside as shown in FIG. 1 (a) or FIG. 1 (b), the respective ferromagnetic particles in the MR fluid 14 attract each other to form a chain-like cluster structure and semisolidify. . That is, the disc rotor 12a and the electromagnet yoke 11a of the fixing member 11 are connected via a chain cluster structure. Then, when the disk rotor 12a moves relative to the fixing member 11 with the rotation of the disk rotor 12a, the chain-like cluster structure is sheared. Further, immediately before shearing, a stress is generated, and this stress acts as a sliding resistance between the fixing member 11 and the disk rotor 12a, that is, as a braking force 18 for rotation.

  In addition, in the situation where the application of the magnetic field is continued, the sheared chain-like cluster structure immediately bonds with nearby fragments (aggregates of ferromagnetic particles) to form a new chain-like cluster structure. This chain-like cluster structure shears again as the disk rotor 12a rotates, and a stress is generated accordingly. The continuous repetition of the operation as described above causes the generation of the braking force 18 to continue. The change in kinetic energy due to the braking force 18 is converted to the thermal energy of the MR fluid 14.

  That is, when the electromagnet coil 16 is energized, the braking mechanism 10 generates the braking force 18 by the action of the MR fluid 14. Further, since the magnitude of the braking force 18 is irrelevant to the difference in the direction of the magnetic fields 17F and 17R, the difference in the braking force 18 does not occur between the state of FIG. 1 (a) and the state of FIG. 1 (b). Of course, if the magnitude of the magnetic field 17F or 17R changes, the braking force 18 also changes.

  On the other hand, as shown in FIG. 1 (a) or 1 (b), when the state where the direct current magnetic fields 17F and 17R are generated is maintained long or a large direct current magnetic field is applied, the electromagnet yoke 11a included in this magnetic circuit. For example, magnetization may occur to form a permanent magnet. When such a permanent magnet is formed, even when the electromagnet coil 16 is not energized, the state where the magnetic field is applied to the MR fluid 14 is maintained, and the electromagnet yoke 11 a and the disc rotor 12 a , And the aggregation of the ferromagnetic particles in the MR fluid 14 moves while being dragged. In other words, the brake can not be completely released. Therefore, it is necessary to suppress the magnetization of the electromagnet yoke 11a or the like, to demagnetize it, and to reduce the adverse effect of the permanent magnet.

  In order to generate the braking force 18 by the braking mechanism 10 shown in FIGS. 1 (a) and 1 (b), it is necessary to energize the electromagnet coil 16, so it is essential to secure a power supply. However, there is a possibility that a failure may occur in a power supply such as an on-vehicle battery that supplies power to the braking mechanism 10, and a situation in which the output voltage of the power supply is abnormally reduced may be considered. Therefore, it is important to be able to secure the braking force 18 of the braking mechanism 10 even when a failure or the like occurs in the power supply.

<Configuration Example of Electronic Circuit>
An exemplary configuration of an electronic circuit for controlling the electromagnet coil 16 of the braking mechanism 10 shown in FIGS. 1A and 1B is shown in FIG.

  The electronic circuit shown in FIG. 2 includes four switching devices Q1 to Q4 connected in H bridge form to both ends 16a and 16b of the electromagnet coil 16, a current detection unit 23, a brake ECU (electronic control unit) 30, and Is equipped.

  Further, this electronic circuit uses a main battery 21 and a sub battery (spare power supply) 22 mounted on the vehicle as a power supply. It is assumed that a voltage such as 12 [V], 24 [V], or 48 [V] is used as the output voltage of the main battery 21 and the sub battery 22. Further, the voltage of the main battery 21 and the voltage of the sub battery 22 do not necessarily have to be the same.

  Each of the switching devices Q1 to Q4 is a MOS type field effect transistor (FET), and is used to switch on / off the energization of the electromagnet coil 16 and to switch the direction of the currents i1 and i2. The current detection unit 23 includes, for example, a resistor, and is used to detect the magnitude of the currents i1 and i2.

  In the switching device Q1, the high potential side terminal (source) is connected to the positive electrode output terminal of the main battery 21 via the first power supply line 24, and the low potential side terminal (drain) is one terminal 16a of the electromagnet coil 16. And connected. In the switching device Q4, the high potential side terminal (drain) is connected to one terminal 16a of the electromagnet coil 16 and the drain of the switching device Q1, and the low potential side terminal (source) is connected to the common line 26. There is.

  In the switching device Q3, the high potential side terminal (source) is connected to the positive electrode output terminal of the sub battery 22 through the second power supply line 25, and the low potential side terminal (drain) is the other terminal 16b of the electromagnet coil 16. And connected. In the switching device Q2, the high potential side terminal (drain) is connected to the other terminal 16b of the electromagnet coil 16 and the drain of the switching device Q3, and the low potential side terminal (source) is connected to the common line 26. There is.

  The negative electrode output terminals of the main battery 21 and the sub battery 22 are connected to the ground line 27 respectively. Further, a current detection unit 23 is connected between the common line 26 and the ground line 27.

  The brake ECU 30 can individually turn on / off the switching devices Q1 to Q4 by applying control signals SG1 to SG4 which are binary signals to the control terminals (gates) of the switching devices Q1 to Q4.

  For example, when the switching devices Q1 and Q2 are controlled to be on while the switching devices Q3 and Q4 are off, the current i1 can flow through the electromagnet coil 16. That is, from the positive electrode output terminal of the main battery 21, the first power supply line 24, the switching device Q1, the terminal 16a, the electromagnet coil 16, the terminal 16b, the switching device Q2, the common line 26, the current detection unit 23, the ground line 27, and the main A current path passing through the negative output terminal of the battery 21 is formed, and a forward current i 1 flows through the electromagnet coil 16.

  When the switching devices Q3 and Q4 are controlled to be on while the switching devices Q1 and Q2 are in the off state, the current i2 can flow through the electromagnet coil 16. That is, from the positive electrode output terminal of sub battery 22, second power supply line 25, switching device Q3, terminal 16b, electromagnet coil 16, terminal 16a, switching device Q4, common line 26, current detection unit 23, ground line 27, and sub A current path passing through the negative output terminal of the battery 22 is formed, and a reverse current i 2 flows in the electromagnet coil 16.

  If the switching devices Q1 and Q4 are turned on at the same time, the first power supply line 24 and the ground line 27 are short-circuited and a large current flows. Therefore, it is necessary to control such a situation not to occur. Similarly, it is necessary to control so that the switching devices Q3 and Q2 are not simultaneously turned on.

  A current detection signal SG5, a first monitoring signal SG6, a second monitoring signal SG7, and a braking instruction signal SG8 are applied to the input terminals of the brake ECU 30 shown in FIG. The current detection signal SG5 is a signal representing the current value of the current i1 or i2 detected by the current detection unit 23. The first monitoring signal SG6 is a signal for monitoring a failure or voltage abnormality of the main battery 21. For example, by monitoring the potential difference between the first power supply line 24 and the ground line 27, it is possible to detect a failure or voltage abnormality of the main battery 21. The second monitoring signal SG7 is a signal for monitoring a failure or voltage abnormality of the sub battery 22. For example, by monitoring the potential difference between the second power supply line 25 and the ground line 27, it is possible to detect failure or voltage abnormality of the sub-battery 22. The braking instruction signal SG8 is a signal representing the on / off and the amount of depression of the brake pedal in the vehicle.

  The brake ECU 30 monitors the current detection signal SG5, the first monitoring signal SG6, the second monitoring signal SG7, and the braking instruction signal SG8 according to a program incorporated in advance, and controls the appropriate control signals SG1 to SG4 according to the situation. By outputting, the brake control of the braking mechanism 10 can be performed.

  Further, in the case of a general automobile, since four braking mechanisms 10 are provided independently for each of the four wheels, the brake ECU 30 mounted on the automobile is configured to be able to control the four braking mechanisms 10 simultaneously. Ru.

<Example of configuration of in-vehicle system>
The major components of a system for controlling four braking mechanisms mounted on a vehicle are shown in FIGS. 3 (a) and 3 (b). FIGS. 3A and 3B show states in which current flows in different directions.

  The in-vehicle braking system shown in FIGS. 3A and 3B includes four independent braking mechanisms 10FL, 10FR, 10RL, and 10RR. That is, the braking mechanisms 10FL, 10FR, 10RL, and 10RR are respectively connected to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel of the vehicle. Also, electromagnet coils 16FL, 16FR, 16RL and 16RR are provided in the braking mechanisms 10FL, 10FR, 10RL and 10RR, respectively.

  Further, in any of the four braking mechanisms 10FL, 10FR, 10RL, and 10RR, the high potential side terminal of the switching device Q1 is connected to the main battery 21 via the first power supply line 24, and the high potential side of the switching device Q3 The terminal is connected to the sub battery 22 via the second power supply line 25. Although not shown in FIGS. 3A and 3B, the low potential side terminals of the switching devices Q2 and Q4 are connected via the common line 26 and the current detection unit 23 as in FIG. Are connected to the ground line 27.

  Then, when the vehicle is braked, the brake ECU 30 that controls this in-vehicle braking system controls to the state shown in FIG. 3 (a) or FIG. 3 (b).

  In the state of FIG. 3A, the switching devices Q3 and Q4 are turned off and the switching devices Q1 and Q2 are turned on for any of the four braking mechanisms 10FL, 10FR, 10RL, and 10RR. That is, the electric power of the main battery 21 causes a current i1 to flow in a path passing through the switching device Q1, the electromagnet coil 16, and the switching device Q2. Therefore, the braking force 18 is generated in each of the braking mechanisms 10FL, 10FR, 10RL, and 10RR by the magnetic field 17F (see FIG. 1A) generated by the current i1 of the electromagnet coils 16FL, 16FR, 16RL, and 16RR.

  In the state of FIG. 3B, the switching devices Q1 and Q2 are turned off and the switching devices Q3 and Q4 are turned on for any of the four braking mechanisms 10FL, 10FR, 10RL, and 10RR. That is, the electric power of the sub battery 22 causes a current i2 to flow through the path passing through the switching device Q3, the electromagnet coil 16, and the switching device Q4. Therefore, the braking force 18 is generated in each of the braking mechanisms 10FL, 10FR, 10RL, and 10RR by the magnetic field 17R (see FIG. 1B) generated by the current i2 of the electromagnet coils 16FL, 16FR, 16RL, and 16RR.

  In the case of control as shown in FIG. 3A, since the power supply power is supplied from the common main battery 21 to the four braking mechanisms 10FL, 10FR, 10RL, and 10RR, four systems of switching devices Q1 and By turning on and off Q2 simultaneously, the same current i1 can be supplied to each system. Further, in the case of control as shown in FIG. 3B, since the power supply power is supplied from the common sub-battery 22 to the four braking mechanisms 10FL, 10FR, 10RL, and 10RR, the switching devices of four systems are provided. By turning on and off Q3 and Q4 simultaneously, the same current i2 can be supplied to each system.

  Therefore, in any state of FIG. 3 (a) and FIG. 3 (b), the braking forces 18 generated in the four braking mechanisms 10FL, 10FR, 10RL and 10RR have the same magnitude. Therefore, even when the output voltages of the main battery 21 and the sub-battery 22 are different, it is possible to brake the four-wheeled vehicle in a stable state. In addition, it is also possible to appropriately adjust the balance of the braking force of the four wheels in order to enable more stable braking of the vehicle. For example, if the length of time for which the currents i1 and i2 are energized is adjusted for each of the four wheels, the balance of the magnitudes of the braking forces 18 can be changed.

<Operation Example of In-Vehicle System-1>
An operation example 1 of a system for controlling four braking mechanisms is shown in FIG. For example, when the brake ECU 30 shown in FIG. 2 controls the four braking mechanisms 10FL, 10FR, 10RL, and 10RR shown in FIGS. 3 (a) and 3 (b), this corresponds to the operation of FIG. Implement control. The operation of FIG. 4 will be described below.

  The brake ECU 30 first selects the energization direction to the electromagnet coil 16 of each braking mechanism 10 (S11). For example, in the initial state, the state (see FIG. 3A) in which the forward current i1 is supplied to each of the four electromagnet coils 16FL, FR16, 16RL, and 16RR is selected by the power supply power supplied by the main battery 21.

  When the brake ECU 30 detects “braking instruction is present” by monitoring the braking instruction signal SG8, the process proceeds from S12 to S13, and performs energization control on the electromagnet coil 16 according to the current selection state. For example, since the forward current i1 is selected in S11 in the initial state, the switching devices Q1 and Q2 are controlled to be on in S13 while the switching devices Q3 and Q4 are off. Implement the same control for all four systems. By this control, for example, as shown in FIG. 3A, the current i1 flows in each system.

  The brake ECU 30 detects the current value for each system by monitoring the current detection signal SG5 in a state in which the electromagnet coil 16 of each system is energized (S14). Furthermore, by comparing the detected current value with, for example, a predetermined threshold value, the presence or absence of an abnormality in the current value is identified for each system (S15).

  Then, when an abnormality in the current value is detected in at least one of the four systems, the process proceeds from S15 to S16. In that case, the brake ECU 30 performs switching of the energization directions of all four systems. For example, when an abnormality is detected in a state where the forward current i1 is selected in the initial state, switching is performed so as to select the reverse current i2. As a result, when the conduction control is performed in S13 and thereafter, the switching devices Q1 and Q2 are turned off and the switching devices Q3 and Q4 are turned on, so that the current i2 in the reverse direction as shown in FIG. Flows to the electromagnet coil 16 of each system.

  For example, if the main battery 21 fails or the switching device Q1 or Q2 fails in any of the four systems while the brake ECU 30 selects the current i1 in the forward direction, an abnormality in the current value occurs. As detected in S15, the energization direction of each system is switched in S16. In the case where sub battery 22 fails or switching device Q3 or Q4 fails in any of the four systems while brake ECU 30 selects current i2 in the reverse direction, an abnormality in the current value occurs. As detected in S15, the energization direction of each system is switched in S16. That is, the brake ECU 30 controls so as to select a circuit of a normal system in which a failure does not occur. Thereby, even in the case of the failure of the power supply system or the circuit failure, it is possible to secure the braking force necessary for the vehicle to decelerate or stop.

  On the other hand, when the brake ECU 30 detects that the braking instruction has been released, it proceeds from S12 to S17 and stops the energization of the electromagnet coil 16 of each system. That is, all the switching devices Q1 to Q4 are controlled to be off. This releases all the braking forces of the four wheels.

  When a predetermined time has elapsed after the release of the braking instruction, the brake ECU 30 proceeds to the processing of S18 to S19. Then, demagnetization control is performed. That is, when the direct current i1 or i2 is continuously supplied to the electromagnet coil 16, the electromagnet yoke 11a or the like may be magnetized due to the influence of the magnetic field 17F or 17R generated thereby, and a permanent magnet may be formed. In this case, the braking force 18 of the braking mechanism 10 can not be completely released even if the energization of the electromagnet coil 16 is stopped in S17 or the like. Therefore, in order to eliminate the formed permanent magnet, demagnetization control is performed in S19 in the example of FIG.

  Specifically, the switching devices Q1 to Q4 are on / off controlled to alternately flow currents i1 and i2 different in direction from each other to the electromagnet coil 16 to form an alternating magnetic field having a waveform such as a sine wave. In addition, control is performed so that the alternating current magnetic field is gradually attenuated from a large state to a small state. Further, in the case of the circuit configuration of FIG. 2, since the amplitudes of the currents i1 and i2 can not be changed, the magnitude of the generated alternating magnetic field is adjusted by adjusting the pulse width used to turn on and off the currents i1 and i2. .

  In addition, when the abnormality of the current value is detected in S15, it is assumed that the driver of the vehicle or the like is notified of the occurrence of the failure by a lamp display or the like (not shown). As a result, it is possible to bring the vehicle to a dealer or the like and quickly repair the broken part. Further, even in the case of such a failure, since the braking function is secured, it is possible to drive the vehicle and move to the dealer.

<Operation Example of In-Vehicle System-2>
An operation example-2 of a system for controlling four braking mechanisms is shown in FIG. For example, when the brake ECU 30 shown in FIG. 2 controls the four braking mechanisms 10FL, 10FR, 10RL, and 10RR shown in FIGS. 3 (a) and 3 (b), this corresponds to the operation of FIG. Implement control. The operation example shown in FIG. 5 is a modification of the operation shown in FIG. Among the operations shown in FIG. 5, the contents of portions different from those in FIG. 4 will be described below.

  In the operation of FIG. 5, it is assumed that the brake ECU 30 has a special “diagnostic mode” to diagnose failure of the switching devices Q1 to Q4, the main battery 21, the sub battery 22, and the like. For example, it is assumed that the transition from the normal mode to the "diagnosis mode" is made when a certain switch operation is detected or when a specific condition is satisfied.

  If the current value detected in S14 is not abnormal, the brake ECU 30 proceeds from S15B to S21 and determines whether or not the "diagnosis mode" is in effect. If the "diagnosis mode" is selected, the process proceeds from step S21 to step S22, and it is determined whether a predetermined time has elapsed. Then, every time a predetermined time passes in the "diagnosis mode", the process proceeds to S23, and switching of the energization directions of all the four systems is performed. Further, since S23 is periodically executed at fixed time intervals, the brake ECU 30 alternately switches between the forward current i1 and the reverse current i2.

  By alternately switching between the forward current i1 and the reverse current i2, failure diagnosis of all the systems related to brake control becomes possible. For example, if all of main battery 21 and switching devices Q1 and Q2 are normal in a state where current i1 flows in the forward direction, the current value detected by current detection unit 23 becomes normal, so that current detection unit 23 detects It becomes possible to detect the presence or absence of a failure of the main battery 21 and the switching devices Q1 and Q2 based on the current value.

  Further, in the state where current i2 flows in the reverse direction, if all of sub battery 22, switching devices Q3 and Q4 are normal, the current value detected by current detection unit 23 becomes normal, so current detection unit 23 detects It becomes possible to detect the presence or absence of failure of the sub-battery 22 and the switching devices Q3 and Q4 based on the current value.

  Also, by alternately switching between the forward current i1 and the reverse current i2, an alternating current flows through the electromagnet coil 16 and the directions of the magnetic fields 17F and 17R are periodically switched, so the electromagnet yoke 11a It is possible to suppress the magnetization of the like.

<Operation Example of In-Vehicle System -3>
An operation example-3 of a system for controlling four braking mechanisms is shown in FIG. For example, when the brake ECU 30 shown in FIG. 2 controls the four braking mechanisms 10FL, 10FR, 10RL, and 10RR shown in FIGS. 3 (a) and 3 (b), this corresponds to the operation of FIG. Implement control. The operation example shown in FIG. 6 is a modification of the operation shown in FIG. Among the operations shown in FIG. 6, the contents of portions different from those in FIG. 5 will be described below.

  If the current value detected in S14 is not abnormal, the brake ECU 30 proceeds from S15B to S31 and carries out diagnosis of the power supply of each system. That is, based on the states of the first monitoring signal SG6 and the second monitoring signal SG7, the presence or absence of a failure or voltage abnormality of each of the main battery 21 and the sub battery 22 is identified. When a failure or voltage abnormality of the main battery 21 or the sub battery 22 is detected, the process proceeds from S32 to S16, and when both the main battery 21 and the sub battery 22 are normal, the process proceeds to S21.

  The electromagnet coil 16 of each braking mechanism 10 can be configured by winding one lead around the electromagnet core 15, but two or more leads may be wound around the electromagnet core 15 to form the electromagnet coil 16. May be configured.

  Also, in the circuit shown in FIG. 2, the energization of the electromagnet coil 16 is controlled using four switching devices Q1 to Q4 connected in an H bridge shape, but, for example, the problem of response speed like a parking brake In applications where it is difficult to cause problems, relays etc. may be used instead.

  Further, in the circuit shown in FIG. 2, although two systems of the main battery 21 and the sub-battery 22 are used as the power supply, another system power supply is further added to select one of the plurality of power supplies. The circuit may be configured to be useful. Further, although the redundancy is reduced, instead of using two systems of the main battery 21 and the sub-battery 22 as power supplies, one battery may be commonly used for the first power supply line 24 and the second power supply line 25. In this case, even if a failure occurs in any one of the switching devices Q1 to Q4, the braking force can be secured by switching the directions of the currents i1 and i2 of the electromagnet coil 16.

<Advantages of brake device and in-vehicle braking system>
In the brake device shown in FIG. 2, the power source power output from one of the main battery 21 and the sub battery 22 is selectively supplied to the electromagnet coil 16 by the control of the switching devices Q1 to Q4 and the generated magnetic fields 17F and 17R. Thus, the braking force 18 is generated. Therefore, even if a failure occurs in either one of main battery 21 and sub-battery 22 or the voltage is abnormally reduced, it is necessary to decelerate or stop the vehicle by switching the selection of the power supply. Braking force 18 can be reliably secured. Moreover, since the braking force 18 is generated using the MR fluid 14, there is no moving part such as an electric motor, so the durability is high and the reliability is improved.

  Further, in the case of the on-vehicle braking system shown in FIGS. 3A and 3B, the electromagnetic coils 16FL, 16FR, 16RL, and 16RR of the braking mechanisms of the four wheels share a common power supply (the main battery 21 or the sub Since power is simultaneously supplied from the battery 22), it is easy to make the braking forces 18 applied to the four wheels the same, and it is possible to brake so that the vehicle maintains a stable state.

  On the other hand, the braking mechanism 10 as shown in FIGS. 1 (a) and 1 (b) has a structure that generates the braking force 18 using the MR fluid 14, and therefore the electromagnet yoke 11a etc. However, there is a possibility that the braking force can not be completely released even when de-energized. However, in the brake device shown in FIG. 2, the directions of the currents i1 and i2 of the electromagnet coil 16 can be switched to switch the direction of the generated magnetic fields 17F and 17R. Thereby, magnetization can be suppressed.

  Further, when the directions of the currents i1 and i2 are periodically switched in steps S22 and S23 shown in FIG. 5, the magnetization can be suppressed more effectively. Furthermore, as in step S19 shown in FIG. 4, the AC magnetic field is generated by the electromagnet coil 16 and the demagnetization control is performed, whereby the permanent magnet generated by the magnetization can be eliminated.

  Further, in the case where the directions of the currents i1 and i2 are periodically switched in steps S22 and S23 shown in FIG. 5, it becomes possible to constantly diagnose each part of the circuit including the spare power supply system not normally used. And improve the reliability of the brake system.

Here, the features of the brake device and the in-vehicle braking system according to the embodiment of the present invention described above will be briefly summarized and listed in the following [1] to [5].
[1] A fixed member (11), a movable member (rotary body 12) disposed at a position facing the fixed member, a space (13) between the movable member and the fixed member, and a magnetic field And a magnetic field generating unit (electromagnetic coil 16) for applying a magnetic field to the functional fluid, the brake device comprising:
The magnetic field generator is
At least one electrical coil (electromagnetic coil 16),
A first switch circuit (switching devices Q1 and Q2) connected between an output of a first power supply unit (main battery 21) and the electric coil to control energization of a current in a first direction of the electric coil;
A second switch circuit (switching devices Q3 and Q4) connected between an output of a second power supply unit (sub-battery 22) and the electric coil to control energization of current in a second direction of the electric coil;
An electronic control unit (brake ECU 30) that selectively controls the first switch circuit and the second switch circuit in accordance with a predetermined braking instruction;
A brake device comprising:

[2] A first switch (switching device Q1) that controls connection between an output (first power supply line 24) of the first power supply unit and a first terminal (16a) of the electric coil. And a second switch (switching device Q2) for controlling the connection between the second terminal (16b) of the electric coil and the common low potential line (common line 26),
The second switch circuit controls a connection between an output of the second power supply unit (second power supply line 25) and the second terminal of the electric coil (switching device Q3); And a fourth switch (switching device Q4) for controlling the connection between the first terminal of the coil and the low potential line,
The electronic control unit allows connection of the first switch and the second switch when the third switch and the fourth switch are both off, and when the first switch and the second switch are both off. Allow connection of a third switch and the fourth switch,
The brake apparatus as described in said [1] characterized by the above-mentioned.

[3] The electronic control unit monitors the state of at least a part of the first switch circuit, the second switch circuit, the first power supply unit, and the second power supply unit, and detects a failure or abnormality Automatically switching the selection state of the first switch circuit and the second switch circuit (S13, S16),
The brake apparatus as described in said [1] or [2] characterized by the above-mentioned.

[4] The electronic control unit periodically and alternately selects the first switch circuit and the second switch circuit when a predetermined condition is satisfied, and switches the energization state of the electric coil (S22, S23, S13),
The brake device according to any one of the above [1] to [3], characterized in that

[5] The above-mentioned brake devices (braking mechanisms 10FL, 10FR, 10RL, and B) provided with a plurality of the brake devices according to any one of the above [1] to [4] and having independent braking states of a plurality of wheels mounted on a vehicle. Vehicle braking system controlled by 10 RR),
The electronic control unit (brake ECU 30) simultaneously supplies common power to the brake devices of the plurality of wheels from the output of the selected power supply system among the first power supply unit and the second power supply unit ( 3 (a) and 3 (b)),
An on-board braking system characterized by

10 braking mechanism 11 fixed member 11a electromagnet yoke 12 rotor 12a disk rotor 13 space 14 MR fluid 15 electromagnet core 16 electromagnet coil 17F, 17R magnetic field 18 damping force 21 main battery 22 sub battery 23 current detector 24 first power line 25 2 Power supply line 26 Common line 27 Ground line 30 Brake ECU
i1, i2 current Q1, Q2, Q3, Q4 switching device SG1, SG2, SG3, SG4 control signal SG5 current detection signal SG6 first monitoring signal SG7 second monitoring signal SG8 braking command signal

Claims (5)

A fixed member, a movable member disposed at a position facing the fixed member, and a functional fluid which is filled in a space between the movable member and the fixed member and whose viscoelasticity changes in response to the application of a magnetic field And a magnetic field generating unit for applying a magnetic field to the functional fluid.
The magnetic field generator is
At least one electrical coil,
A first switch circuit connected between an output of the first power supply unit and the electric coil to control energization of current in a first direction of the electric coil;
A second switch circuit connected between an output of a second power supply unit and the electric coil to control energization of current in a second direction of the electric coil;
An electronic control unit that selectively controls the first switch circuit and the second switch circuit in accordance with a predetermined braking instruction;
Brake device comprising: The first switch circuit includes a first switch for controlling connection between the output of the first power supply unit and the first terminal of the electric coil, and a low potential line common to the second terminal of the electric coil. And a second switch to control the connection,
The second switch circuit includes a third switch for controlling connection between the output of the second power supply unit and the second terminal of the electric coil, the first terminal of the electric coil, and the low potential line And a fourth switch that controls connection of the
The electronic control unit allows connection of the first switch and the second switch when the third switch and the fourth switch are both off, and when the first switch and the second switch are both off. Allow connection of a third switch and the fourth switch,
The brake device according to claim 1. The electronic control unit monitors the state of at least a part of the first switch circuit, the second switch circuit, the first power supply unit, and the second power supply unit, and detects a failure or an abnormality. Automatically switching the selection state of the first switch circuit and the second switch circuit,
The brake device according to claim 1 or 2. The electronic control unit periodically and alternately selects the first switch circuit and the second switch circuit when the predetermined condition is satisfied, and switches the energization state of the electric coil.
The brake device according to any one of claims 1 to 3. An on-vehicle braking system comprising a plurality of braking devices according to any one of claims 1 to 4, wherein the braking states of a plurality of wheels mounted on a vehicle are controlled by the respective independent braking devices,
The electronic control unit simultaneously supplies common power to the brake devices of the plurality of wheels from the output of the selected power supply system among the first power supply unit and the second power supply unit.
In-vehicle braking system.

Images