JPS61166760A - Braking control unit for vehicles - Google Patents

Abstract

PURPOSE:To omit a hydraulic transfer pipe line as well as to improve reliability in a control unit, by installing a piezoelectric control cylinder in a wheel cylinder, while operating this piezoelectric control piston with a brake operation detecting signal and performing its control. CONSTITUTION:A control unit (unillustrated herein) emits a braking command with a brake operation signal, lowering voltage to be fed to a piezoelectric mechanism 272 of a piezo-piston 27, and makes the capacity smaller. Therefore, a control piston 273 moves in a direction where an oil chamber 28 expands, and simultaneously a volumetric control piston 30 also moves so as to expand the capacity of an oil chamber 23. Under this condition, the control unit closes a control valve 34 and closes up the oil chamber 23 tight. After that, high voltage is fed to the piezoelectric mechanism 272, and when the piezo-piston 27 is expanded longer, the volumetric control piston 30 is driven whereby oil pressure is produced in the oil chamber 23. With this oil pressure, a brake piston 22 is driven, thus braking takes place. Feed voltage of the piezo-piston 27 is controlled whereby braking pressure is controlled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a system for applying braking commands to each wheel of a vehicle such as an automobile in response to a braking command corresponding to a brake pedal operation, etc. The present invention relates to a braking control device for a vehicle that applies braking force.

[Background Art] A braking device that is set for a vehicle such as an automobile and which restricts and controls the rotation of wheels usually uses hydraulic pressure from brake oil. In other words, brake oil is supplied to the wheel cylinder set for each wheel from a master cylinder activated in response to a brake operation, and the brake piston in the wheel cylinder is driven to rotate together with the wheel, for example. A braking friction force is applied to a brake disc that is set in a state where the

In this case, the above-mentioned master cylinder is set in a state in which it moves to the brake pedal set at the driver's seat of the car, and from the master cylinder located close to the driver's seat to the wheel cylinder part set corresponding to each wheel. , piping for transmitting hydraulic pressure is installed.

However, in such a brake pipe that transmits the hydraulic pressure from the master cylinder to the wheel cylinder, in addition to a change in the compression of the oil due to the action of pressure, expansion occurs in the pipe due to the action of the oil pressure.

For this reason, a transmission delay exists in the hydraulic transmission system.

For example, when trying to perform traction control, anti-skid control, etc. using such a braking mechanism, for example, during traction control, a slip state of a wheel is detected and the wheel cylinder of the wheel that is causing this slip is control the valves in the hydraulic circuit to supply hydraulic pressure and brake the rotation of the wheel.

However, in a state where there is a delay in the hydraulic transmission system as described above, it becomes difficult to execute highly responsive and effective control. Further, in order to perform traction control, anti-skid control, etc. using the control valve of the hydraulic circuit, the configuration thereof becomes extremely complicated.

[Problems to be Solved by the Invention] This invention has been made in view of the above points, and in particular, it is possible to simplify the configuration of the brake system by eliminating the hydraulic piping from the brake pedal section. In addition, in response to the generation of braking commands such as brake pedal operation, braking force is effectively generated for each wheel, and furthermore, as a configuration that allows the omission of a hydraulic transmission system, It is an object of the present invention to provide a braking control device for a vehicle that is highly effective in improving reliability.

[Means for solving the problems] That is, in the vehicle braking device according to the present invention,
Brake oil is supplied in a common state to the wheel cylinders set for each wheel, and the
Each piston is configured to include a piezoelectric element whose volume is controlled by voltage control, and a brake oil supply passage for each of the wheel cylinders is provided.
Control valves are set to open and close this passage in close proximity to each wheel cylinder. Then, in a state where a braking command is generated, the piston volume is set to a small value and the control valve is closed, and in this state, voltage is supplied to the piezoelectric element to control the volume expansion, and a braking force to the wheels is generated. The purpose is to ensure that

[Function 1] In the brake control device configured as described above, for example, when the brake pedal is operated, a brake command signal is generated from the detection means that detects the operation state. In response to this command signal, the volumes of the control valve and piezoelectric element are controlled to generate braking force for each wheel. In this case, the supply of hydraulic pressure to the wheel cylinders corresponding to each wheel is not controlled (therefore, there is no need to arrange piping for transmitting hydraulic pressure from the part corresponding to the brake pedal. The hydraulic pressure that performs the braking action is generated in each wheel cylinder, and the state of hydraulic pressure generation is controlled by piezoelectric elements with good response.For this reason, the hydraulic pressure is extremely responsive. Since there is no hydraulic piping, it has a great effect on improving reliability.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows, for example, a brake control system in an automobile, in which brake mechanisms 121 to 124 are set for each wheel 111 to 114 to perform brake control, respectively. 121 to 124 are set to be supplied with brake oil from the reserve tank 13, respectively. In this case, the brake oil supply circuit is set such that the front wheels 111, 112 and the rear wheels 113, 114 are separated.

The brake mechanisms 121 to 124 are configured such that a braking operation is executed for each wheel by volume control means each including a piezoelectric element, and the moving operation state is controlled by a braking command from the electronic control unit 14, for example. It is now controlled by settings.

The control unit 14 is supplied with a detection signal generated when the brake pedal 16 is depressed from a brake operation detection circuit 15. At this time, the control unit 14 controls the supply of a voltage signal to the brake mechanisms 121 to 124 to expand the volume of the piezoelectric element. Here, the brake operation detection circuit 15
A commonly used brake switch can be used, and it may be configured to generate a signal whose value is set depending on the depression pressure, amount, etc. of the brake pedal 16.

FIG. 2 shows one of the brake mechanisms 12 set for each wheel as described above, and the brake mechanism 12 is constructed within the brake caliper 20. That is, inside this caliper 20 is a wheel cylinder 21.
A brake piston 22 is set inside this wheel cylinder 21. and,
Brake oil from the reserve tank 13 is supplied to an oil chamber 23 set in the wheel cylinder 21 by the piston 22 through an oil passage 24.

The brake piston 22 has a cylindrical shape, for example, and has a cylinder 26 partitioned by a partition wall 25 formed therein, and a piezoelectric piston mechanism 27 is installed in the cylinder 26. . This piezoelectric piston mechanism 27 includes a substrate 271 fixed to the opening of the cylinder 26 by a screw mechanism, and a piezoelectric mechanism 272 configured by laminating a plurality of disc-shaped piezoelectric elements on the substrate 271. Attach and set one end face part. A control piston 273 that forms an oil chamber 28 between the piezoelectric mechanism 272 and the partition wall 25 is attached to the free end portion of the piezoelectric mechanism 272. When voltage is supplied to the piezoelectric mechanism 272 set in this way, the volume of the piezoelectric mechanism 272 is expanded, the control piston 273 is driven in a direction approaching the partition 25, and the volume of the oil chamber 28 is increased. It acts to reduce the That is, by controlling the voltage supplied to the piezoelectric mechanism 273, hydraulic pressure is generated in the oil chamber 28 and controlled by II.

A plurality of small pistons 29 are set in the partition wall 25 so as to penetrate into the oil chamber 28 . This small piston 29 is installed integrally with a volume control piston 30 set inside the brake piston 22, and the area of the working surface of this small piston 290 is the same as that of the control piston 273. It is set so that it is sufficiently smaller than the area. Although a plurality of the small pistons 29 are shown in this embodiment, the present invention can be implemented in the same manner even if only one small piston 29 is used.

That is, when the volume of the piezoelectric mechanism 272 changes due to voltage, the control piston 273 is moved in accordance with the change in volume, and the volume of the oil chamber 28 is changed. When the volume of this oil chamber 28 changes, the oil pressure within this chamber 28 changes, and this oil pressure change comes to drive the small piston 29, which in turn drives the volume control piston 30.

In this case, although the amount of change in volume of the piezoelectric mechanism 272 is small, the amount of movement of the control piston 213 is small.
In other words, since the control piston 273 and the small piston 29 constitute a displacement magnification mechanism, the displacement control piston 30 is controlled to be driven by a sufficient amount. .

Here, the piezoelectric mechanism 272 is set by stacking a plurality of disk-shaped piezoelectric elements as described above, and electrodes are set between each piezoelectric element, and these electrodes allow a plurality of piezoelectric elements to be stacked. The piezoelectric elements are connected in parallel. The voltage applied to the piezoelectric elements connected in parallel is then controlled by the electronic control unit 14.

A brake pad 31 is installed on the brake piston 22 configured as described above, especially on the surface of the piezoelectric piston 27 on the side opposite to the oil chamber 23, and this brake pad 31 is attached to the caliper 20. On the other hand, the attachment is such that the brake disc 33, which rotates integrally with the wheel, is sandwiched between the set brake pads 32. That is, the brake pad 31 is moved while the brake piston 22 expands in volume, and is brought into pressure contact with the brake disc 33, so that a braking force is applied to the disc 33.

A control valve 34 is provided for the oil passage 24. The control valve 34 is composed of a piezoelectric mechanism 341 in which a plurality of piezoelectric elements are laminated, and a switching valve 342 that is driven by the expansion/extension operation of the piezoelectric mechanism 341 to close the passage 24. By applying a high voltage to the piezoelectric mechanism 341, the switching valve 342 closes the passage 24, seals the oil chamber 23 in the wheel cylinder 21, and seals the brake oil in the oil chamber 23. It is intended to do so.

That is, in the device configured as described above, when the brake pedal 16 is depressed, this operating state is detected by the detection circuit 15, and the detection signal is supplied to the electronic control unit 14. . This control unit 14 generates a braking command in response to the detection signal, and this braking command first sets the voltage supplied to the piezoelectric mechanism 272 of the piezoelectric piston 21 to a low state. , the volume is set to be reduced.

In this state, the control piston 273 is moved in the direction of enlarging the oil chamber 28.
8, the volume control piston 30 is also set to be driven in the direction of enlarging the oil chamber 23 of the wheel cylinder 21. Therefore, in this state, the oil chamber 23 of the wheel cylinder 21 is set to the most expanded state, and the oil chamber 23 is filled with brake oil via the oil passage 24.

With the oil chamber 23 of the wheel cylinder 21 set to be enlarged in this manner, a high voltage is applied to the piezoelectric mechanism 341 of the control valve 34, and the oil passage 24 is closed by the switching valve 342. The oil chamber 23 is fixedly set to a specific volume state. Then, the piezoelectric piston 27
When a high voltage is applied to the piezoelectric mechanism 272 and the piezoelectric mechanism 272 is expanded and expanded, the displacement control piston 30 is driven in a state where the displacement amount is expanded in response to the movement of the control piston 273 corresponding to this expansion and expansion. Become so. this'
In this case, since the volume of the oil chamber 23 is fixed to the state specified by the control valve 34 as described above,
The movement of the volume control piston 30 is now expressed as the movement of the brake piston 22, and the brake pad 31
comes into pressure contact with the brake disc 33, and braking is applied to the wheel.

In this case, the braking force acting on the wheels is the brake pedal 16
The brake operation detection circuit 15 also detects, for example, the depression pressure of the pedal 16 and sends a signal corresponding to the detected pressure to the control unit 14. supply. The control unit 14 may control the voltage applied to the piezoelectric mechanism 272 of the piezoelectric piston 27 in response to the detected depression pressure, so that the amount of expansion and extension of the piezoelectric mechanism 272 is controlled.

In addition, instead of analog voltage control, the piezoelectric mechanism 272
If the voltage applied to the brake disc 3 of the brake pad 31 is supplied in a pulsed state and the duty of the applied voltage in the pulsed state is controlled,
This makes it possible to effectively subtract the pressure acting on the third part.

In the brake control device configured in this way, the reliability is improved by constantly checking the capacitance of the piezoelectric mechanism 272 by the control unit 14. By further detecting the displacement amount using a piezoelectric element or the like stacked on another layer, the operating state of the braking force can be reliably observed, and the braking force can be controlled effectively.

Furthermore, the locked state of the wheels is detected based on the relationship between the rotational state of the wheels and the vehicle speed, and the control unit 14 uses this detection signal.
If a braking command is generated from the wheel, effective braking control will be executed only for those wheels that are in a locked state and are in a slipping state. Specifically, when a wheel lock state as described above occurs in the brake operation state, the voltage applied to the piezoelectric mechanism 272 of the brake mechanism corresponding to the wheel that is in the locked state is controlled to be reduced to reduce the braking force. This allows the lock to be released from the locked state.

Furthermore, if a wheel slips during starting, it is possible to apply braking to the wheel and reduce its rotational speed so that the starting operation can be performed efficiently.

In the brake control device configured as described above, the brake operation state is detected electrically, and the control unit 14
However, in case a failure occurs in such a command means, it is effective to consider a backup mechanism. FIG. 3 shows an embodiment that takes this point into consideration, and an emergency power source 41 is set. This emergency power source 41 is configured to be activated when it is detected that a failure such as a disconnection has occurred in the engine control unit 14.
In such a failure state, a high voltage is applied to the piezoelectric mechanism 272 so that a braking operation is automatically performed.

Moreover, it goes without saying that the operation may be controlled by this emergency power source through manual operation.

FIG. 4 shows still another embodiment, in which the front wheel 111
．． Switching valves 45 and 46 are respectively set for the piping 42 and 43 between the reserve tank 13 corresponding to each system of the 112 and rear wheels 113 and 114. The switching valves 45, 46 are normally set to an open state, and are controlled to be closed when a failure including a disconnection occurs in part or all of the brake mechanisms 121 to 124. Furthermore, emergency capacity control mechanisms 47 and 48 are set for the pipes 42 and 43, respectively.

The capacity control mechanisms 47 and 48 are composed of, for example, a PS pump, an accumulator, etc., and each has a function of pumping brake fluid to the pipes 42 and 43.

That is, when the control unit 14 detects the occurrence of a failure, the switching valves 45 and 46 are
Alternatively, a drive command is given to one side corresponding to the piping system in which the failure has occurred, and the piping passage with the reserve tank 13 is closed. That is, the control valve 34 of the brake mechanism is set to a state equivalent to being closed, and in this state, the emergency capacity control mechanisms 47 and 48 are driven to send brake oil into the pipes 42 and 43. A braking operation is performed in a brake mechanism connected to each pipe. It goes without saying that the backup operation in such a failure state can be controlled manually, not only based on commands from the control unit 14 as described above.

In the above embodiment, the piezoelectric mechanism 272 and the volume control piston 30 are set in the brake piston 22 of the wheel cylinder 21. It can also be implemented by providing .

Further, when the brake pads 31 and 32 are worn out, an adjustment mechanism may be added to correct the stroke and keep the gap with the brake disc 33 constant.

[Effects of the Invention] As described above, the vehicle braking control device according to the present invention does not directly generate hydraulic pressure by operating the brake pedal, and therefore does not transmit the hydraulic pressure. It is possible to create a configuration that does not require any piping. The hydraulic pressure for performing the braking operation is applied to the brake ms that is set corresponding to each wheel, and the brake fluid can be distributed from a reserve tank or the like to the brake mechanism part of each wheel. It is. Therefore, the configuration is extremely simplified, and the occurrence of failures related to the hydraulic transmission mechanism can be reliably eliminated. In addition, since the hydraulic control that affects braking is carried out in the brake caliper of the brake mechanism installed on each wheel, there are no problems such as compression of oil or expansion of pipes due to pressure, and it is extremely effective. Brake control is executed with good responsiveness, and anti-skid control, traction control, etc. can also be executed effectively, and this has a great effect on improving the function of the braking mechanism.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the configuration of a brake control device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a brake mechanism set corresponding to each wheel used in the brake control device. The block diagram, FIG. 3, and FIG. 4 are block diagrams explaining other embodiments of the present invention, respectively. 111-114...wheels, 12,121-124...
・Brake mechanism, 13... Reserve tank, 14...
・Electronic control unit, 15...Brake operation detection circuit, 16...Brake pedal, 20...Brake caliper, 21...Wheel cylinder, 22...Brake piston, 23.28...Oil Chamber, 24... Oil passage, 25... Partition wall, 21... Piezoelectric piston, 272
... Piezoelectric mechanism, 30... Capacity control piston, 33.
...Brake disc, 34...Control valve.

Claims (2)

[Claims] (1) A wheel cylinder configured for a brake caliper set corresponding to each wheel, and a piston configured to include a piezoelectric mechanism set within the wheel cylinder and controlled to expand and contract by voltage control; A means for setting and supplying brake oil to each of the wheel cylinders, a control valve that is set close to the wheel cylinder and that controls opening and closing of a brake oil supply passage that is supplied to each of the wheel cylinders, and a brake operation. command signal generating means for generating a braking command signal; and in response to the braking command signal from the means, controlling voltage applied to the piezoelectric mechanism of the piston with the control valve closed to control expansion or contraction of the volume thereof; 1. A braking control device for a vehicle, characterized in that the braking force is applied to a corresponding wheel in a state where the piston volume is expanded by the means. (2) The above-mentioned volume-controlled piston is configured to include a cylinder inside, and within this cylinder is a piezoelectric piston configured with a piezoelectric element whose volume changes by voltage control, and a piezoelectric piston configured to change the volume by voltage control. Therefore, it is composed of an oil chamber filled with oil whose volume is controlled, and this oil chamber has a sufficiently smaller working surface than the working surface of the piezoelectric piston, and is set so that the driving piston projects therefrom. A control piston for setting oil pressure in the wheel cylinder is connected to the driving piston, so that a change in volume of the piezoelectric piston is magnified and appears as a change in volume on the control piston. A braking control device for a vehicle as described in .