JPH0380664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a servo brake for an automobile, and particularly to an electromagnetic servo brake device that utilizes electromagnetic force for boosting.

Servo brakes use vacuum, compressed air, pressurized fluid, etc. as a boosting medium, and input the pedal force from the brake pedal via an operating rod to a boosting device that uses the above-mentioned boosting medium. This boosts the force and outputs it to the push rod that pushes the piston of the brake master cylinder, thereby generating braking oil pressure in the master cylinder. This braking hydraulic pressure is transmitted to the brake pedal via the push rod, booster, and operating rod, and is felt by the driver's feet as a reaction force.

In such a servo brake, it has been proposed to use an electromagnet instead of using negative pressure or fluid as described above in the booster. This makes it possible to downsize the entire servo brake device and simplify the structure of the control system. (For example, Japanese Patent Application No. 57-139629) In a servo brake that uses such electromagnetic force, a force proportional to the pedal force applied to the brake pedal generates braking hydraulic pressure in the brake master cylinder due to the boosting effect of the electromagnetic force. The brake is applied while keeping the reaction force and pedal force at a constant boost ratio.
In such electromagnetic servo brakes, braking oil pressure is generated at a predetermined boost ratio relative to the pedal force, but this boost ratio can be changed depending on vehicle conditions such as vehicle weight and vehicle speed. is desirable. In other words, when the vehicle weight is large or the vehicle speed is high, a large braking force is required, so it is desirable to increase the boost ratio, and conversely, when the vehicle weight is small or the vehicle speed is low, A large braking force is not required; on the contrary, it can be said that a small braking force is desirable in order to achieve quiet braking.

In response to such demands, it is an object of the present invention to provide an electromagnetic servo brake device that can change the boost ratio depending on the state of the vehicle.

The electromagnetic servo brake device of the present invention includes a pedal force transmitting means for transmitting the pedal force on the brake pedal to the brake master cylinder, an electromagnetic means for generating braking hydraulic pressure in the brake master cylinder by electromagnetic force, and a brake provided in the pedal force transmitting means. It consists of a pedal depression force detection means, a braking oil pressure (reaction force) detection means of the brake master cylinder, and a control means that receives the outputs of both detection means and controls an electromagnetic means so as to maintain both outputs in a predetermined boosting relationship. , the pedal force transmitting means is divided at an intermediate portion thereof, and an intermediate member is interposed in the intermediate portion for applying an electromagnetic force by the electromagnetic means, and the pedal force detecting means and the braking oil pressure detecting means are arranged with the intermediate member sandwiched therebetween. The control means is provided in each of the pedal force transmission means to detect the pressure acting between the pedal force transmission means and the intermediate member, and the control means controls a predetermined boosting relationship depending on the weight, speed, etc. of the vehicle. It is characterized by being able to change the boost ratio.

In the electromagnetic servo brake of the present invention, an intermediate member for applying an electromagnetic force by the electromagnetic means is interposed in the intermediate part of the divided pedal force transmission means, and the pedal force transmission means is provided with a pedal force detection means and a braking oil pressure detection means, respectively, with this intermediate member sandwiched therebetween. A simple and compact means is provided, and from the pressure acting between the pedal force transmitting means and the intermediate member, the pedal force applied to the brake pedal and the push rod pushing force of the master cylinder are changed as resistance values using different pressure sensitive plates. Based on this detection signal, an electromagnet that obtains an electromagnetic force that assists the pushing force of the push rod is activated to constitute a brake boosting mechanism. The electromagnet can be operated automatically or manually depending on the vehicle's weight, speed, etc., and then operate the electromagnet based on the changed signal. The push rod assist force can be controlled, and the optimum brake braking characteristics (relationship between brake pedal depression force and braking force) can be obtained in each state.

Embodiments of the present invention will be described below with reference to the drawings.

The example shown in FIG. 1 will be described in detail below in conjunction with FIGS. 2 to 4.

An operating rod 2 is connected to the brake pedal 1 via a connecting shaft 1a, and a conductive plate 2a is integrally fixed to the tip of the operating rod 2. On the other hand, a push rod 3 for pushing the master cylinder piston (not shown) of the brake master cylinder 4 is disposed coaxially with the operating rod 2, and the operating rod 2 and the push rod 3 transfer the depression force of the brake pedal 1 to the brake master cylinder 4. A pedal force transmitting means is configured to transmit the pedal force to the pedal. Further, a conductive plate 3a is fixed to the operating rod side end of the push rod 3, and both conductive plates 2a, 3
a are arranged in parallel, and two pressure-sensitive rubber sheets A and B are superimposed on each other with a movable plate 5 as an intermediate member interposed therebetween. Pressure-sensitive rubber sheets A and B are fixed to the front and back surfaces of conductive plates 2a and 3a and movable plate 5, respectively, and pressure-sensitive rubber sheet B serves as a depressing force detection means for detecting the depressing force applied to brake pedal 1. It is configured as a braking oil pressure detection means for detecting the braking oil pressure generated in the brake master cylinder 4. (The structure of this part is shown exploded in FIG. 2.) The push rod 3 and the conductive plate 3a are insulated from each other, or the push rod 3 is formed of an insulator. At least the portion of the movable plate 5 in contact with the pressure-sensitive rubber sheets A and B is electrically conductive, and this portion is grounded. the two conductive plates 2a,
3a is provided with an output terminal a for detecting brake pedal depression force and an output terminal b for detecting master cylinder braking oil pressure, respectively.

The movable plate 5 is fixed to a magnetic member 6 made of ferromagnetic material such as iron via two legs 5a, and this magnetic member 6 has a cylindrical shape with a through hole for the push rod 3 in the center. It is movable in the axial direction. An iron case 7 containing an electromagnetic coil 8 is disposed around the magnetic member 6, and when the electromagnetic coil 8 is energized, the magnetic member 6 is moved to the left in the figure along the push rod 3 by electromagnetic force. , brake master cylinder 4
Electromagnetic means for generating braking hydraulic pressure is configured. Since the magnetic member 6 is fixed to the movable plate 5, the magnetic member 6, which moves to the left due to the excitation of the electromagnetic coil 8, moves the movable member 5 to the left, and the pressure-sensitive rubber sheet B that is in close contact with the magnetic member 6 moves to the left. Push the push rod 3 to the left. Since the push rod 3 receives braking hydraulic pressure from the master cylinder 4, the pressure sensitive rubber sheet B receives pressure corresponding to the reaction force.

The magnetic member 6 is further provided with a spring force that counteracts the pedal force applied to the brake pedal by an arm or flange 9 fixed to the magnetic member 6 and a coil spring 10 interposed between the arm or flange 9 and the case 7. ing. The two pressure-sensitive rubber sheets A and B have pressure-sensitive electrical properties such that their resistance decreases as the applied pressure increases.

These pressure-sensitive rubber sheets A and B are connected to an electric circuit as shown in FIG. In other words, output terminals a and b of pressure-sensitive rubber sheets A and B each have a resistance of 1
The voltage e a at output terminal _a is determined by the resistance value of resistor 16 and pressure sensitive plate A, and the voltage e _b at output terminal b is determined by the resistance value of resistor 17 and pressure sensitive plate B. It is determined by the resistance value of The voltage e _b of the output terminal b is input to the (-) side of the variable differential amplifier 11, and the voltage of the power supply Vcc is input to the (+) side.
The set voltage e ₀ is maintained by the Zener diode 15 and inputted. The output voltage e _b ' of the variable differential amplifier 11 is input to the (-) side of the differential amplifier 12, and the constant voltage e ₀ is input to the (+) side. Furthermore, the output voltage e _b ″ of the differential amplifier 12 is input to the (+) side of the comparator 13, and the output voltage e b ″ is input to the (+) side of the comparator 13, and
The voltage e _a is input to the (-) side. The output of the comparator 13 is connected to the base of a transistor 14 to turn the transistor 14 on and off. The aforementioned electromagnetic coil 8 has one terminal c connected to the power supply Vcc and the other terminal d connected to the collector of the transistor 14, and is demagnetized or excited by turning the transistor 14 ON or OFF.

The variable differential amplifier 11 has its (+) side input connected to the (+) side terminal of the OP amplifier 11a via a resistor 11c (resistance value Ri), and its (-) side input connected to the resistor 11b.
(-) of the OP amplifier 11a via (resistance value Ri)
Connect to the side terminal. Furthermore, the (+) side terminal of the OP amplifier 11a is grounded via a variable resistor 11d (resistance value Rv), and the output terminal and (-) side terminal are connected via a variable resistor 11e (resistance value Rv). ing. Therefore, the (+) side input voltage e ₀ and the (-) side input voltage e _b of the variable differential amplifier 11
The relationship between the output voltage e b ′ and the output voltage e _b ′ can be expressed as e _b ′=Rv/Ri (e ₀ −e _b ), and this is expressed as equation (B). However, the resistance values of the variable resistors 11d and 11e are changed simultaneously so that they always have the same value. Similarly, the (+) side input of the differential amplifier 12 is connected to the (+) side terminal of the OP amplifier 12a via the resistor 12c (resistance value R ₁ ), and the (-)
The side input is connected to the (-) side terminal of the OP amplifier 12a via the resistor 12b (resistance value R ₁ ), and then the OP
The (+) side terminal of the amplifier 12a is grounded via a resistor 12d (resistance value _R1 ), and the output terminal and (-) side terminal are connected via a resistor 12e (resistance value _R1 ). Therefore, the input/output relationship of the first differential amplifier circuit 12 can be expressed as e _b ″=(e ₀ =e _b ′), which is expressed as equation (C).

Next, the operation of the electromagnetic servo brake device having the above configuration will be explained. First, considering the time when the pedal 1 is not depressed, in this case no pressure acts on the pressure sensitive plates A and B, and the resistance value at this time is the maximum. In this embodiment, at this time, the output terminals a,
Resistor 16, so that voltages e _a and e _b at b are both e ₀ ,
A resistance value of 17 is set. When e _b = e ₀ , the formula
In (B), e _b ′=0, and in equation (C), e _b ″=e ₀ , so both inputs of the comparator 13 become e ₀ , and this output e _c =LOW. Therefore, the transistor 14 is turned off, and the electromagnetic coil 8 is also demagnetized.
This state is represented in the graph of Fig. 4 by the point where the force applied to the pressure-sensitive rubber sheet is 0 and the voltages e _a , e _b ″ become e _0.Next , when the brake pedal 1 is depressed with a certain force, The pedaling force is transmitted to the pressure-sensitive rubber sheet A via the operating rod 2, and this resistance is reduced.If the pressure-sensitive rubber sheet pressing force at this time is F _A , the pressure-sensitive rubber sheet pressing force and the output terminal a The relationship between voltage e _a and voltage e a is set to a linear proportional relationship shown by line A in Figure 4, and when the pressing force of pressure sensitive rubber sheet A is F _A , voltage e _a = e ₁ . Here, assuming that the electromagnetic coil 8 remains demagnetized and no electromagnetic force is generated, the pressure-sensitive rubber sheet B also receives a reaction force whose applied force becomes F _A. Therefore, the resistance value of the pressure-sensitive rubber sheet B becomes smaller, and at this time the voltage at output terminal b becomes
If e _b = e ₄ , then from the relationship of equations (B) and (C), e _b ″=e ₀ (1-Rv/Ri)-Rv/Ri・e ₄ , and the resistance value Rv of the variable resistor 11e is If it is constant, e _b ″ becomes a linear function of e ₄ , that is, a linear function of e _b . Therefore, if e _b ″=e ₂ at this time, then e ₂
<e ₁ , and the pressing force and voltage of pressure-sensitive rubber sheet B
e _b ″ is the point (0, e ₀ ) shown by line B(L) in Figure 4.
and a straight line passing through the point (F _A , e ₂ ). At this time, the (+) side of the input of the comparator 13 is e _b ″=
e ₂ , the (-) side is e _a = e ₁ and e ₂ > e ₁ , so the output is
e _c =HIGH, which turns on the transistor 14 and excites the electromagnetic coil 8. This electromagnetic coil 8
Due to the excitation, the pressure-sensitive rubber sheet B is further pushed toward the master cylinder, and the resistance value of the pressure-sensitive rubber sheet B is further reduced. Therefore, the (+) side input e _b '' of the comparator 13 also becomes smaller and is balanced at the point where it becomes equal to the (-) side input. In other words, in FIG. 4, the point (F _A , e ₂ ), the pressure on the pressure-sensitive rubber sheet B increases due to electromagnetic force, and the voltage increases.
As e _b ″ becomes smaller, a point on line B(L) (F _B (L), e ₁ )
Move to the point indicated by and balance. As described above, an electromagnetic servo brake device is obtained which amplifies the master cylinder pressing force to F _B (L) with respect to the brake pedal pressing force F _A.

In this device, the resistance value of the variable resistor 11e
Consider the case when Rv is changed to Rv′ (Rv>Rv′).
Similarly to the previous example, when no electromagnetic force is generated, when the brake pedal is pressed and the pressure on pressure-sensitive rubber sheet A is F _A , the pressure on pressure-sensitive rubber sheet B is also F _B
The voltage at output terminal b is also e _b = e ₄ , but since the resistance value of variable resistor 11e is Rv >Rv', e _b ″=e ₀ (1−Rv′/Ri) −Rv′/Ri・e _4. In this case, if e _b ″=e ₃ , then e ₃ > e ₂ , and in Fig. 4, the pressing force and voltage of pressure-sensitive rubber sheet B are
The relationship between e _b '' is a line B(H) passing through the point (0, e ₀ ) and the point ( _FA , e ₃ ). At this time, the input of the comparator 13 is e _{3 on the (+) side and e 3} on the (-) side. Since the side is e ₁ , the output e _c = HIGH
As a result, the electromagnetic coil 8 is excited. Therefore, in the same way as in the previous case, in Fig. 4, a point (F _A ,
e ₃ ) to the point (F _B (H), e ₁ ) and balance.
In other words, the resistance value Rv of the variable resistor 11e is Rv′(Rv＞
Rv′), the master cylinder pressing force changes from F _B (L) even if the pressing force F _A of the operating rod 2 that transmits the pressing force of the brake pedal 1 is the same.
Changes to F _B (H) (F _B (L) < F _B (H)). That is, depending on the resistance value of the variable resistor 11e, the pressing force of the pressure-sensitive rubber sheet B can be freely set within the range shown by diagonal lines between line B(L) and line B(H) in FIG. Note that the resistance value may be changed manually by the driver, or may be changed automatically according to conditions such as vehicle weight and speed.

As explained above, according to the electromagnetic servo brake device of the present invention, the resistance value of the variable resistor can be freely changed manually by the driver, or automatically depending on the vehicle weight, speed, etc. This allows you to set any braking characteristics according to the driver's preference, or adjust the vehicle weight,
Automatically set the optimal brake braking characteristics for each condition depending on the speed, etc. (for example, when the vehicle weight is large or the vehicle speed is high, the boost relationship is increased to improve the effectiveness of the brakes). This is desirable from the viewpoints of driving, operability, and safety.

Further, an intermediate member for applying an electromagnetic force by an electromagnetic means is provided at the intermediate portion of the divided pedal force transmitting means, and a pedal force detecting means and a braking oil pressure detecting means provided across the intermediate member are used to detect the contact between the pedal force transmitting means and the intermediate member. It is possible to easily and compactly construct a mechanism that detects both the brake pedal depression force and the master cylinder braking oil pressure from the pressure acting between them, and the boosting characteristics of the electromagnetic servo brake can be precisely determined based on this detection signal. It is something that can be controlled.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main parts of an embodiment of the electromagnetic servo brake of the present invention, Fig. 2 is an exploded perspective view showing its pedal force and reaction force detection section, and Fig. 3 is its electric circuit. The circuit diagram and FIG. 4 are graphs showing the pressure-voltage characteristics of the pressure-sensitive rubber sheet used in the detection section. DESCRIPTION OF SYMBOLS 1... Brake pedal, 2... Operating rod, 2a, 3a... Conductive plate, 3... Push rod, 4... Brake master cylinder, 5...
...Movable plate, 6...Magnetic member, 7...Case, 8...
...Electromagnetic coil, 11...Variable differential amplifier, 12...
... Differential amplifier, 13 ... Comparator, 14 ... Transistor, 15 ... Zener diode, 16,1
7...Resistance, A, B...Pressure sensitive rubber sheet, a...
Output terminal for detecting pedal force, b... Output terminal for detecting braking oil pressure (reaction force), c, d... Electromagnetic coil terminal.

Claims (1)

[Scope of Claims] 1. A pedal force transmitting means for transmitting the pedal force on the brake pedal to the brake master cylinder, an electromagnetic means for generating braking oil pressure in the brake master cylinder by electromagnetic force, and a pedal force transmitting means provided in the pedal force transmitting means to transmit the pedal force applied to the brake pedal. A pedal force detection means for detecting, a brake oil pressure detection means for detecting the braking oil pressure generated in the brake master cylinder, and receiving the output of the pedal force detection means and the output of the brake oil pressure detection means, and maintaining both outputs in a predetermined boosting relationship. The pedal force transmitting means is divided at its middle part, and an intermediate member is interposed in the middle part to apply an electromagnetic force by the electromagnetic means, and the pedal force transmission means is divided at the middle part, and an intermediate member is interposed in the middle part to apply an electromagnetic force by the electromagnetic means. The means and the braking oil pressure detection means are respectively provided on the pedal force transmitting means with the intermediate member in between, and detect the pressure acting between the pedal force transmitting means and the intermediate member, and further, the control means An electromagnetic servo brake device for an automobile, characterized in that the predetermined boosting force relationship can be changed based on a state signal of the automobile. 2. The electromagnetic servo brake device for a motor vehicle according to claim 1, wherein the state signal indicates a state quantity corresponding to the weight of the motor vehicle. 3. The electromagnetic servo brake device for a motor vehicle according to claim 1, wherein the state signal indicates a state quantity corresponding to the vehicle speed of the motor vehicle.