JPS61287855A - Brake device provided with digital operating amount detector - Google Patents

Abstract

PURPOSE:To eliminate control errors due to disturbance and aging effect, by converting an operating amount indicating the operating situation of a brake actuating member into a digital signal and by delivering the thus obtained digital signal to a brake drive device. CONSTITUTION:Rotational speed sensors 40 detect the rotational speeds of right and left wheels 26, and delivers their output signals to a control device 42 which is connected with a brake switch 46 for detecting the depression of a brake pedal 44 as a brake actuating member and an angle detector 48 for detecting the angle of the depressed brake pedal 44. The angle detector 48 includes a digital operating amount detector which delivers a digital signal corresponding to the rotating angle of the brake pedal 44 to the control device 42.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a hydraulic brake system for automobiles, and in particular to improving the reliability and reducing costs of a brake operating section.

BACKGROUND OF THE INVENTION Conventionally, in hydraulic brake systems for automobiles, the operating force of the hydraulic brake is proportional to the operating force of a brake operating member such as a brake pedal.

However, the braking effect of an automobile, that is, the magnitude of deceleration and braking torque generated on the axle, is not determined primarily by the acting force of the hydraulic brake, but is determined by various factors such as the load, the slope of the road surface, the friction coefficient of the brake friction material, etc. Subject to conditions. Therefore, the driver had to take these conditions into consideration when operating the brake operating member.

Therefore, in Japanese Patent Application Laid-open No. 58-188746, etc.,
It has been proposed that the braking effect itself, rather than the acting force of the hydraulic brake, is uniquely determined by the operating force of the brake operating member. The brake drive device that applies the hydraulic brake determines a target braking effect according to the operating force of the brake operating member, and applies the hydraulic brake so that the actual braking effect is equal to the target braking effect. It is. In this case, a device for detecting the operating force of the brake operating member is naturally required, and conventionally, an operating force detecting device using a load cell or the like using a strain gauge as a detection head has been used.

Furthermore, Japanese Patent Laid-Open No. 57-51562 discloses that in a brake system equipped with both a fluid brake and a friction brake, when the braking effect of only the fluid brake is insufficient, the friction brake is applied to compensate for the shortage. In this brake system, the amount of operation of the brake pedal is detected by a potentiometer in order to correlate the sum of the braking effects of the fluid brake and the friction brake with the operation status of the brake pedal. It has become. But like this 1? IM
Rather than a special brake system in which multiple types of brakes are applied by a single brake operating member, in a normal automobile hydraulic brake system in which only a hydraulic brake is applied by a single brake operating member, the brake operating member The operation status was detected by the operating force detection device as described above.

Problems to be Solved by the Invention However, the analog signal obtained from a detection head such as a load cell is usually extremely weak, so a processing circuit with a large amplification factor is required, and the output is likely to become unstable. However, there were problems in that the cost increased, and it was easy to change over time (and it was difficult to stably detect the operating force).

Means for Solving the Problem In order to solve this problem, the present invention uses a conventional hydraulic brake (as described above, a plurality of types) in which a hydraulic brake is applied so as to obtain a braking effect according to the operation of a brake operating member. Even in hydraulic brake systems for automobiles (not special brakes that apply), the braking effect is made to correspond to the amount of operation of the brake operation member rather than the operation force, and the amount of operation is detected. The detector directly converts the operating amount of the operating member into a digital signal, and supplies this to the brake drive device as a signal representing the operating status of the brake operating member.

Function and Effect In the brake device configured as described above, a digital signal corresponding to the operation amount of the brake operating member is supplied from the digital operation amount detector to the brake drive device, and the brake drive device performs braking corresponding to this digital signal. Activate the hydraulic brakes to effect. Therefore, there is no need for an electronic circuit that processes minute analog signals, as is required when detecting the operating status of brake operating members using an operating force detector such as a load cell, and the system is reliable with fewer control errors caused by disturbances and aging. This results in a hydraulic brake device for automobiles that is highly versatile.

In addition, in the conventional hydraulic brake device, the braking effect corresponds to the operating force of the brake operating member, whereas in the brake device according to the present invention, the braking effect corresponds to the operating amount of the brake operating member. Therefore, the feeling of operating the brake operating member by the driver will be slightly different from the conventional one, but once you get used to it, there will be no problem.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, reference numeral 10 is a tank for storing brake fluid, and a pump 12 pumps up the brake fluid from this tank 10 and supplies it to a fluid passage 14.

However, since the liquid passage 14 is provided with a normally closed electromagnetic on-off valve 16, the pumped brake fluid is stored in the accumulator 18.

The accumulator 18 is provided with a hydraulic pressure switch (not shown), and when the hydraulic pressure reaches a set value, the drive motor of the pump 12 is stopped.

A rapid pressure reduction valve 20 and a slow increase pressure reduction valve 22 are connected in parallel to each other downstream of the electromagnetic on-off valve 16, and two wheel cylinders 24 are connected further downstream thereof.

These wheel cylinders 24 operate hydraulic brakes that suppress rotation of the left and right front wheels 26.

The rapid pressure reducing valve 20 is always in a pressure increase permitting state that communicates the wheel cylinder 24 with the accumulator 18, but by supplying an intermediate current to the solenoid 28, it is switched to a pressure holding state that cuts off communication between the two. Furthermore, by supplying a large current to the solenoid 28, the solenoid valve is a three-position solenoid valve that can be switched to a pressure reduction permitting state in which the wheel cylinder 24 is communicated with the tank 10. Slow increase pressure reducing valve 2
2 is also a three-position solenoid valve having the same structure as the rapid pressure reducing valve 20, but the control of the current supplied to the solenoid 30 is different. That is, when it is necessary to gradually increase the hydraulic pressure in the wheel cylinder 24, a current is supplied to the solenoid 30 to alternately switch the gradual pressure increase/reducing valve 22 between a pressure increase permissible state and a pressure hold permissible state in short cycles. Furthermore, when it is necessary to gradually reduce the hydraulic pressure in the wheel cylinder 24, a current is supplied to the solenoid 30 to alternately switch the gradual pressure reducing valve 22 between a pressure reduction permissible state and a pressure holding state in short cycles. be.

The rotational speed of the left and right front wheels 26 is detected by a rotation sensor 40, and its output signal is supplied to a control device 42. Further connected to the control device 42 are a brake switch 46 that detects the depression of a brake pedal 44 as a brake operating member, and an angle detector 48 that detects the depression angle of the brake pedal 44.

As shown in FIG. 2, the angle detector 48 includes a plurality of groups of electrodes 52.54.
an electrode plate 60 in which electrodes 8 are arranged along concentric arcs;
Movable body 7 having a plurality of sliders 62, 64°66.68
0. Each group of electrodes 52, 54, 56
And 58 is an arcuate lead part for each group? 2,7
They are connected to each other by 4.76 and 78, and have a comb-like shape. Then, one of the electrode plate 50 and the movable body 70 is fixed to the brake pedal 44, and the other is fixed to a pedal bracket (not shown) that rotatably supports the brake pedal 44. When the pedal 44 is depressed, the slider 62 .
64. 66 and 68 are electrodes 52, 54 and 5, respectively.
6.58 intermittently. Each slider 62, 64, 66, 68 is connected to the control device 42 by a mutually independent lead wire, and when these sliders are in contact with each electrode 52, 54, 56, 58, the control device 42 is controlled. A high level signal "1" is supplied to the device 42, and a low level signal "0" is supplied when there is no contact. Sliders 62, 64, 66.
The position of each electrode is determined in relation to the output signal from 68 as shown in the following table.

That is, each time the brake pedal 44 rotates by a certain angle, a high level signal is output from the slider 62, and when the output signals of the other sliders 64, 66, and 68 are viewed as one set, the output signal is 1 at a time. It is designed to represent an increasing binary number.

That is, the angle detector 48 is connected to the sliders 64, 66 and 68.
The signal from the slider 62 constitutes a digital operation amount detector that supplies a digital signal corresponding to the rotation angle of the brake pedal 44 to the control device 42, and the signal from the slider 62 will be clear from the later explanation. This serves as a timing pulse for causing the control device 42 to take in the digital signal. In the illustrated example, the rotatable range of the brake pedal 44 is divided into eight equal parts, but in reality, it is desirable that it be divided into about 16 or 32 equal parts.

The control device 42 is mainly a computer,
The rotation sensor 40. Based on the signals from the brake switch 46 and the angle detector 48, the electromagnetic on-off valve 16. The rapid pressure reducing valve 20 and the slow increasing pressure reducing valve 22 are controlled to make the deceleration of the automobile correspond to the amount of operation of the brake pedal 44, and for this purpose, the ROM of the computer contains the deceleration map shown in FIG. The pressure increasing/reducing valve control map shown in FIG. 5 and the control program shown in FIG. 6 are stored.

The deceleration map in FIG. 3 is arranged as shown in FIG. Areas IA, IB, C, 2B, and 2A extending above and below the area are set, and these are mapped. That is, the entire range of the operation amount θ of the brake pedal 44 is divided into the same number of stages as the number of divisions of the angle detector 48, and the width of each region is set stepwise for each stage. Area C
IB is a region where the deceleration g is appropriate and the brake force should be maintained as it is, and IB is a region where the deceleration g is slightly excessive, so the gradual increase pressure reducing valve 22 is operated and the wheel cylinder 2 is
IA is a region where the hydraulic pressure in wheel cylinder 24 should be reduced gradually by operating the rapid pressure reducing valve 20 because the deceleration g is excessive. On the other hand, in region 2B, the deceleration g is slightly too small, so the gradual increase pressure reducing valve 22 should be operated to gradually increase the hydraulic pressure in the wheel cylinder 24, and in region 2A, the deceleration g is too small, so the pressure increases rapidly. This is a region where the pressure reducing valve 20 should be operated to rapidly increase the hydraulic pressure in the wheel cylinder 24.

The pressure increasing/reducing valve control map in FIG. This is a map that indicates what state the pressure reducing valve 20 and the slow increase pressure reducing valve 22 should be in, and in the figure, X means a pressure increase instruction, y means a pressure decrease instruction, and Z means to show off pressure holding. For example, if the deceleration error Δg is in region C, a pressure holding instruction is given to both the rapid pressure reduction valve 20 and the slow increase pressure reduction valve 22, but if the deceleration error Δg changes from the value in region C to the value in region 2B. For example, a pressure increase instruction is given to the slow increase pressure reduction valve 20, and a pressure maintenance instruction is given to the rapid increase pressure reduction valve 20. Then, when the deceleration error Δg changes to the value in the region 2A, a pressure holding instruction is given to the slow increase pressure reducing valve 22, and a pressure increasing instruction is given to the rapidly increasing pressure reducing valve 20. Further, when the deceleration error Δg changes from the value in region 2B to the value in region C, after a pressure reduction instruction is once given to the slow increase pressure reduction valve 22 to which a pressure increase instruction was given,
The pressure holding instruction is given, and the pressure holding instruction continues to be given to the rapid pressure reducing valve 20 to which the pressure holding instruction was given. Similarly, when the deceleration error Δg changes between other regions, predetermined instructions are given to the rapid increase pressure reduction valve 20 and the slow increase pressure reduction valve 22 according to the arrows in FIG.

As is clear from the above explanation, tank 10° pump 1
2. Solenoid on-off valve 16. Accumulator 18, rapid pressure reducing valve 20. Slow increase pressure reducing valve 22. A brake in which a control device 42 or the like determines a deceleration according to the operation amount of a brake pedal 44, which is a brake operation member, as a target braking effect, and applies a hydraulic brake so that the actual braking effect becomes equal to the target braking effect. It constitutes a driving device.

Next, the operation of the present brake system will be explained with reference to the flowchart shown in FIG.

When the brake pedal 44 is not depressed, the electromagnetic on-off valve 16 is closed and the accumulator 1 is closed.
8 stores a predetermined amount of brake fluid, and both the rapid increase pressure reduction valve 20 and the slow increase pressure reduction valve 22 are in a pressure increase permitting state. Further, the computer of the control device 42 repeatedly executes step S1 in FIG. 6 and stands by in preparation for depression of the brake pedal 44.

When the brake pedal 44 is depressed, a high level signal is generated from the brake switch 46, the determination result in step S1 becomes YES, and step S2 is executed.

The control device 42 opens the electromagnetic on-off valve 16.

Subsequently, in step S3, it is determined whether there is an interrupt request or not.
That is, it is determined whether or not a high level signal (timing pulse) is being supplied from the slider 62 in FIG. The value of θ (θn
) is updated, step S5 is executed, and if there is no interrupt request, step S5 is executed immediately. The target deceleration 3n applied to the operation amount θn of the brake pedal 44 is calculated based on the operation amount θn of the brake pedal 44 stored in the RAM and the equation 3n=αθn.

Next, in step S6, the actual deceleration g is calculated from the average value of the output signal of the rotation sensor 40, and in step S7, it is the difference between the calculated actual deceleration g and the target deceleration 3n calculated in step S5. Deceleration error Δg
is calculated.

Furthermore, in step S8, the area in the deceleration map of FIG. 3 is determined based on the manipulated variable θn stored in the manipulated variable register and the deceleration error Δg calculated in step S7, and then in step S9 The passage route is determined.

That is, the result of the area determination in step S8 is 2A.

In the case of either C or IA, as is clear from Fig. 5, one of the pressure increase instruction is 2
If it is B or IB, the instructions are divided into two parts depending on which area the area was entered from, so the route to be taken is determined. Specifically, the area stored in the area register of the computer and the area determined in step S8 are compared, and if they are the same, the program execution moves to step S10, but if they are not the same, from which area? Whether the area has changed is stored in the route register, and the contents of the area register are updated.

Then, in step SIO, one of the pressure increase instruction 28.
30 controls are performed.

Thereafter, in step Sll, it is determined whether a release instruction has been issued or not, that is, whether the placket switch 46 that once outputted a high level signal is in a state where it outputs a low level signal again. At this stage, the brake pedal 44 is depressed and no release instruction has been issued, so the program execution returns to step S3, and from step S3 to step 81.
1 is executed again. By repeating this operation, the rapid increase pressure reduction valve 20 and the slow increase pressure reduction valve 22 are operated as appropriate to control the hydraulic pressure in the wheel cylinder 24, and the automobile is braked at a deceleration corresponding to the operation amount of the brake pedal 44.

If the brake pedal 44 is released while the deceleration control is being performed as described above or after the vehicle has stopped, the determination result in step Sll becomes YES;
Braking termination processing in step S12 is performed. That is, the electromagnetic on-off valve 16 is returned to the closed state, and
After both the rapid pressure reduction valve 20 and the slow increase/decrease/pressure valve 22 are maintained in a pressure reduction permissible state for a certain period of time, they are returned to a pressure increase permissible state. While the pressure reduction valves 20 and 22 are maintained in the pressure reduction permitting state, the brake fluid in the wheel cylinder 24 is returned to the tank 10, the fluid pressure in the wheel cylinder 24 is reduced, and the hydraulic brake returns to the non-operating state.

In the above embodiment, a sliding angle detector 48 is used as a digital operation amount detector, but instead of this, a rotating plate having a large number of slits and a small number of slits corresponding to the slits of the rotating plate are used. It is also possible to use an optical encoder in which a light emitting element and a light receiving element are opposed to each other with a fixed slit plate provided therebetween, and output a digital signal corresponding to the rotation angle of the rotary plate. Further, although the angle detector 48 is of an absolute type, it is also possible to adopt an incremental type detector, and the electrodes 52 provided on the electrode plate 60 and the slits 7 provided on the rotary plate are not necessarily arranged at equal angular intervals. It is not necessary to do so; for example, the angular interval may be gradually increased or decreased as the amount of operation of the brake pedal increases.

Additionally, if the brake operating member performs linear motion, it is possible to use a linear encoder.
Even if the brake operating member itself rotates,
It is also possible to connect the linear encoder to the brake operating member via a mechanism that converts rotational movement into linear movement.

Furthermore, in the embodiment described above, the output signal of the angle detector is directly input to the computer, and the value of the manipulated variable θ is updated by interrupt processing, but the output signal of the manipulated variable detector cannot be received at any time. It is also possible to provide a register that can store the amount of data, and to read the manipulated variable from the register for each control cycle of the computer.

In addition, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art, such as by changing the configuration of the brake drive device, the control map of the control device, the control program, etc.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a hydraulic brake device which is an embodiment of the present invention. FIG. 2 is an explanatory diagram conceptually showing the angle detector in FIG. 1. FIG. 3 is a diagram showing a deceleration map stored in the control device of FIG. 1, and FIG. 4 is a graph for explaining the meaning of the deceleration map. FIG. 5 is a diagram showing a pressure increasing/decreasing valve control map stored in the control device of FIG. 1, and FIG. 6 is a flowchart showing a control program. 12: Pump 16: Solenoid on-off valve 18: Accumulator 2o: Rapid increase pressure reducing valve 22: Slow increase pressure reducing valve 2
4: Wheel cylinder 44 Brake pedal (brake operating member) 48: Angle detector (digital operation amount detector)
50: Substrate 52, 54, 56.58F electrode 60: Electrode plate

Claims (1)

[Scope of Claims] For automobiles equipped with a brake drive device that determines a target braking effect according to the operation status of a brake operating member and applies a hydraulic brake so that the actual braking effect is equal to the target braking effect. In the hydraulic brake device, the digital operation amount detection is characterized in that the brake operation member is connected to a digital operation amount detector that directly converts the operation amount of the operation member into a digital signal and supplies it to the brake drive device. Brake device with equipment.