JP2009019690A - Temperature presumption apparatus of friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature presumption apparatus of a friction material for presuming the temperature of a friction material, based on an exothermic energy on the bases of a brake torque and a wheel angular velocity and the ambient temperature around a brake system. <P>SOLUTION: The temperature presumption apparatus of the friction material comprises: a brake element rotating together with a wheel 16; a friction material for braking the brake element by contacting the brake element; a brake torque sensor 20 installed at the site where distortion of the member under the suspension spring is caused by brake torque during braking, and having a distortion detecting means and thermistor 22; a wheel rotating angular velocity detecting means 24 for detecting a wheel rotating angular velocity; and a friction material temperature presumption means for presuming temperatures of a friction material, based on the wheel rotating angular velocity detected by the wheel rotating angular velocity detection means 24 and the temperature detected by the thermistor 22 of the brake torque sensor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction material temperature estimation device that estimates the temperature of a friction material of a brake device mounted on each wheel of a vehicle.

  In vehicles that can perform traction control (BTCS) by brake force during non-brake operation, if the temperature of the brake friction material rises excessively due to execution of BTCS, the effectiveness of wheel brakes will deteriorate during normal braking by brake operation, etc. In the past, when the execution frequency of the BTCS is frequent, the execution of the BTCS is prohibited, or the brake fluid pressure is reduced by measuring the brake fluid pressure or operating the pump motor or the valve. It has been estimated that the temperature is estimated from the brake fluid pressure, and the execution of BTCS is prohibited when the estimated temperature is equal to or higher than the set temperature.

  As prior art relating to temperature estimation of the friction material, there are Patent Documents 1, 2, and 3.

  Patent Document 1 describes that the brake fluid pressure is estimated from the wheel speed of the wheel, and the temperature of the brake device is estimated based on the brake fluid pressure and the wheel speed of the vehicle.

  Patent Document 2 describes that when the pedal switch is ON, the temperature rise of the friction material is estimated based on the brake initial speed and the brake end speed, and based on the brake fluid pressure when BTCS is being executed.

Patent Document 3 describes that the rising temperature of the friction material is estimated from the wheel speed of the wheel and the brake fluid pressure.
Japanese Examined Patent Publication No. 7-94218- Japanese Patent No. 3314539 Japanese Patent No. 3585707

  However, in the case of determining whether or not BTCS can be executed based on the frequency of BTCS, execution of BTCS is prohibited even though the normal brake fluid pressure is not increased and the temperature of the friction material is not increased. . Moreover, in the method of estimating the temperature of the friction material by the brake fluid pressure, the heat release due to friction of the friction material is not taken into consideration, and although the brake fluid pressure is increased, the friction material is not greatly rubbed. (For example, when the wheel is stopped) Since the temperature drop is calculated even when the temperature does not drop, and the temperature rise is not calculated using the ambient temperature around the brake device, the heat released from the brake device There is a problem that the temperature rise is excessively calculated and the execution of the BTCS is prohibited with a margin because the temperature is not sufficiently considered. Since Patent Documents 1 to 3 are methods for estimating the temperature of the friction material based on the brake fluid pressure, there are the above-described problems.

  The present invention has been made in view of the above problems, and does not estimate the temperature rise of the friction material based on the brake fluid pressure, but the heat generation energy of the friction material and the brake device based on the brake torque and the angular velocity of the wheel. An object of the present invention is to provide a friction material temperature estimation device that estimates the temperature of a friction material based on the ambient temperature around the friction material.

  According to the first aspect of the present invention, the wheel is rotatably supported, the rotation support body is spring-supported by the vehicle body by the suspension, the brake element rotating together with the wheel, and the brake element in contact with the brake element. A friction material temperature estimation device for a brake device including a friction material for braking, wherein the friction material temperature estimation device is provided at a portion where distortion occurs due to brake torque during braking of a member under the spring of the suspension, and a strain detection means and a thermistor are provided. A brake torque sensor, wheel rotation angular velocity detection means for detecting the rotation angular velocity of the wheel, brake torque detected by the brake torque sensor, wheel rotation angular velocity detected by the wheel rotation angular velocity detection means, and detection by the thermistor Friction material temperature estimating means for estimating the temperature of the friction material based on the measured temperature Temperature estimating device of the friction material, characterized in that the is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the friction material temperature estimating means includes the brake torque detected by the brake torque sensor and the wheel rotation detected by the wheel rotation angular velocity detecting means. Based on the angular velocity, a heat generation energy calculating means for calculating heat generation energy generated by the friction between the friction material and the brake element, and a unit heat amount radiating the temperature detected by the thermistor and the heat amount of the brake element. Based on a heat radiation resistance that is a necessary temperature difference between the brake element and the atmosphere, a heat radiation energy calculation that calculates heat radiation energy to the atmosphere due to a temperature difference between the temperature of the brake element and the atmosphere of the heat accumulated in the brake element And a stored energy accumulated in the brake element based on the heat generation energy and the heat radiation energy. Brake element accumulated energy calculating means for calculating a rugey, and a friction material for estimating the temperature of the friction material based on the stored energy and a heat capacity of the brake element which is energy necessary for raising the brake element by 1 ° C. There is provided a temperature estimation device for a friction material, characterized by comprising a temperature calculation means.

  According to the first aspect of the present invention, since the temperature of the friction material is estimated based on the brake torque, the wheel rotation angular velocity, and the temperature detected by the thermistor of the brake torque sensor, the temperature can be accurately estimated. Even if the brake fluid pressure of the wheels is the same due to uneven wear or unilateral friction material, even if the brake torque of each wheel is different and the friction temperature of each wheel is different, the friction temperature of each wheel is different. Estimation can be performed accurately. Furthermore, the thermistor is provided in the brake torque sensor, and since the ambient temperature around the brake device is detected by the thermistor, the amount of cooling due to heat radiation from the brake device can be accurately calculated, and the friction material is accurately detected. The temperature can be estimated.

  According to the second aspect of the present invention, it is assumed that the temperature of the brake element at which the friction material and the friction material are pressed against each other is equal, and the temperature of the friction material is estimated based on an equivalent circuit related to heat accumulation and heat dissipation of the brake element. Therefore, the temperature of the friction material can be estimated easily and accurately.

  FIG. 1 is a schematic configuration diagram showing a brake system and a drive system of a vehicle according to an embodiment of the present invention. As shown in FIG. 1, the vehicle body 2 includes an engine 4, a throttle valve driving device 5, an automatic transmission 6, an ECU 8, a brake fluid pressure control device 10, a brake pedal 12, a master cylinder 14, a left front wheel 16FL, a right front wheel 16FR, Left rear wheel 16RL, right rear wheel 16RR, left front wheel brake device (abbreviated as brake) 18FL, right front wheel brake 18FR, left rear wheel brake 18RL, right rear wheel brake 18RR, left front wheel brake torque sensor 20FL, right front wheel brake torque sensor 20FR, left rear wheel brake torque sensor 20RL, right rear wheel brake torque sensor 20RR, left front wheel thermistor 22FL, right front wheel thermistor 22FR, left rear wheel thermistor 22RL, right rear wheel thermistor 22RR, left front wheel speed sensor 24FL, right front wheel speed sensor 24FR, left rear wheel speed sensor 24RL and right Equipped with a wheel speed sensor 24RR.

  The engine 4 and the automatic transmission 6 are mounted on the front portion of the vehicle body 2 in order to drive the left front wheel 16FL and the right front wheel 16FR that are drive wheels. The ECU 8 controls the brake hydraulic pressure control device 10 to execute BTCS that exerts a braking force on the front wheel brake corresponding to the front wheel that is likely to cause excessive slip among the left and right front wheel brakes 18FL and 18FR during the non-brake operation. . In addition, the brake fluid pressure control device 10 is controlled so as to execute ABS for adjusting the brake pressure of the wheel brake corresponding to the wheel which is about to fall into the locked state among the wheel brakes 18FL, 18FR, 18RL, 18RR at the time of the brake operation. To do. Further, when an excessive slip is likely to occur on the front wheels during non-braking operation, the throttle valve driving device 5 is controlled to adjust the output of the engine 4 and execute traction control (ETCS) based on the engine output. Furthermore, the temperature of the friction material of brakes 18FL, 18FR, 18RL, and 18RR, which will be described later, is estimated, and the control ratio of BTCS and ETCS is changed based on the estimated temperature.

  Brake fluid pressure corresponding to the depression amount of the brake pedal 12 is output from the first and second output ports 14A and 14B of the tandem master cylinder 14, and both the output ports 14A and 14B are connected to the brake fluid pressure control device 10. Has been. The brake fluid pressure control device 10 adjusts the brake fluid pressure output from the output ports 14A, 14B based on an instruction from the ECU 8, supplies the brake fluid pressure to the brakes 18FL, 18FR, 18RL, 18RR, and brakes 18FL, 18FR, 18RL. , 18RR is activated.

  The brakes 18FL, 18FR, 18RL, 18RR exert braking force according to the brake fluid pressure supplied from the brake fluid pressure control device 10.

  The brake torque sensors 20FL, 20FR, 20RL, and 20RR are provided at portions where distortion is caused by braking torque of a member under the spring of the suspension (not shown), and the brake torque generated by the operation of the brakes 18FL, 18FR, 18RL, and 18RR. Is a brake torque sensor for detecting

  Thermistors 22FL, 22FR, 22RL, and 22RR are provided at locations where heat generation of the brakes 18FL to 18RR is interrupted and easily cooled from the viewpoint of thermal protection, and the ambient temperature around the friction material of the brakes 18FL to 18RR is detected. The brake torque sensors 20FL, 20FR, 20RL, and 20RR are mounted on the brake torque sensors 20FL, 20FR, 20RR, and 20RR to compensate for the temperature dependence of the strain gauges as strain detection means of the brake torque sensors 20FL to 20RR and correct the output of the brake torque sensors 20FL to 20RR. ing.

  Wheel speed sensors 24FL, 24FR, 24RL, and 24RR face the rotary magnetic encoder mounted on the wheels 16FL, 16FR, 16RL, and 16RR, and are fixed to a knuckle near the bearing 72 in FIG. , 16FR, 16RL, 16RR, which is a sensor for detecting the rotational speed, and it is only necessary to be able to detect disconnection with either high / low. It is a line type.

  As will be described later, the brake torque sensors 20FL, 20FR, 20RL, 20RR and the wheel speed sensors 24FL, 24FR, 24RL, 24RR and the ECU 8 are connected by a common 5-core coaxial cable. The wiring between the sensors 20FL, 20FR, 20RL, 20RR, 24FL, 24FR, 24RL, 24RR and the ECU 8 must be adapted to strict conditions such as suspension operation, vibration, and temperature. Providing them separately leads to an increase in cost, but the cost can be reduced and wiring space can be saved by using one 5-core coaxial cable. In addition, the wiring used in common is, for example, a power supply line as described later.

  2 to 5 are diagrams for explaining the brakes 18FL, 18FR, 18RL, and 18RR. Since the brakes 18FL, 18FR, 18RL, and 18RR have the same structure with respect to the wheels 16FL, 16FR, 16RL, and 16RR, the reference numeral is denoted as 18, and the wheels 16FL, 16FR, 16RL, and 16RR are not distinguished.

  As shown in FIGS. 2 and 3, the brake disk (rotor) 52 as a friction element is fixed to the wheel 16 and rotates together with the wheel 16. The knuckle 54 is a wheel support, and rotatably supports the wheel 16 and is connected to the vehicle body 2 via a spring and a suspension link (not shown). The caliper bracket 58 is attached to the knuckle 54 by bolts 40 and 42, and a pair of friction pads (friction materials) disposed on both sides in the axial direction of the brake disc 52 on both the return side and the return side of the brake disc 52. ) 68 and 70 are supported.

  Two slide pins fixed to the brake caliper 56 by two bolts are slidably fitted to the caliper bracket 58, and are moved forward and backward in a direction parallel to the axis of the brake disc 52 to be a friction pad. A piston (pushing member) 62 that presses 68 and 70 toward the brake disc 52 is provided.

  The brake caliper 56 integrally has a wheel cylinder 60, and a piston 62 is fitted in the wheel cylinder 60. The hydraulic pressure from the hydraulic pressure control device 10 is supplied to the piston chamber 64 via the hydraulic pressure supply port 66.

  The brake disc 52 is connected to the hub 53. When the hydraulic pressure from the hydraulic pressure control device 10 is supplied to the piston chamber 64 via the hydraulic pressure supply port 66, the piston 62 is pushed leftward in FIG. 3 and the friction pad 68 is pressed against the brake disc 52.

  The brake caliper 56 moves to the right by the reaction force of the piston 62 pressing the friction pad 68 against the brake disk 52, and the friction pad 70 on the opposite side is also pressed against the brake disk 52 to brake the rotation of the brake disk 52.

  As shown in FIG. 4, a concave portion 58d is formed on the radially outer side surface of the brake disk 52 of the inner connecting portion 58c of the caliper bracket 58, and the sensor plate 78 is fixed to the concave portion 58d by a pair of bolts 74 and 76. Has been. A strain gauge 80 is attached to the sensor plate 78 and the thermistor 22 is mounted. The brake torque sensor 20 includes a strain gauge 80 and an amplifier 82 that amplifies its output.

  When the brake is applied when the vehicle moves forward, the brake disk 52 rotates while the friction pads 68 and 70 press against the brake disk 52, so that the friction pads 68 and 70 are dragged by the brake disk 52 and the brake disk 52. And is brought into pressure contact with the brake load receiving portion 58b of the caliper bracket 58.

  Since the caliper bracket 58 is fixed to the knuckle 54 by screwing the bolts 40 and 42 into the screw holes, a tensile load is applied to the sensor plate 78 fixed to the radially outer side surface of the brake disk 52 of the inner connecting portion 58c. The sensor plate 78 is deformed in the tensile direction by this tensile load. This deformation is detected by the strain gauge 80, and the brake torque is detected based on the strain amount of the sensor plate 78 by amplifying the output of the strain gauge 80 by the amplifier 82.

  When the brake is applied at the time of reverse of the vehicle, the brake disc 52 rotates in the direction opposite to that at the time of forward movement. Therefore, the friction pads 68 and 70 are dragged by the brake disc 52 and moved in the rotation direction of the brake disc 52. The bracket 58 is in pressure contact with the brake load receiving portion 58a. Therefore, a tensile load is generated in the inner connecting portion 58c on the radially outer side of the brake disc 52 even when the vehicle is moving backward. Due to this tensile load, the sensor plate 78 is subjected to tensile deformation, and the amount of deformation is detected by the strain gauge 80. Since a tensile load is applied both when the vehicle is moving forward and when the vehicle is moving backward, the characteristics of the brake torque sensor 20 are symmetrical with respect to the brake torque = 0 as shown in FIG.

  As shown in FIG. 7A, the brake torque sensor 20 is bridge-connected by a strain gauge 80 whose resistance changes due to strain, and the power terminal 20a is a connecting portion of the strain gauge 80 that detects strain as a change in resistance. Connected to 80a. The ground terminal 20b is connected to the connection portion 80b of the strain gauge 80. The connection parts 80c and 80d are connected to the input terminal of the amplifier 82, the voltage between the connection parts 80c and 80d is amplified by the amplifier 82, and the amplified electric signal is output from the output terminal 20c. On the other hand, an electrical signal corresponding to the temperature is output from the output terminal 22 a of the thermistor 22.

  The wheel speed sensor 24 includes a Hall IC 84 and a capacitor 86 that output a signal corresponding to the wheel speed by changing an output according to the flow direction of magnetic fluxes connected in parallel, and a power supply terminal 24a is a positive electrode and a Hall of the capacitor 86. The signal output terminal 24 b is connected to the IC 84 and is connected to the signal terminal of the Hall IC 84 and the negative electrode of the capacitor 86.

  As shown in FIG. 6, the brake torque sensor 20 and the wheel speed sensor 24 are connected to the ECU 8 by a common 5-core coaxial cable 90. The power line 90a of the five-core coaxial cable 90 branches near the bearing 72 supported by the knuckle 54 and is connected to the strain gauge 80 of the brake torque sensor 20 through the power terminal 20a of the brake torque sensor 20. The wheel speed sensor 24 is connected to the power terminal of the Hall IC 84 and the positive electrode of the capacitor 86 through the power terminal 24 a of the wheel speed sensor 24.

  The ground line 90b of the five-core coaxial cable 90 is distributed in the vicinity of the bearing 72, and is connected to the connection portion 80b of the strain gauge 80 of the brake torque sensor 20 through the ground terminal 20b. The signal output terminal 20c of the brake torque sensor 20 and the signal output terminal 22a of the thermistor 22 are accommodated in the 5-core coaxial cable 90 through the output signal lines 90c and 90e and connected to the ECU 8.

  The signal output terminal 24b of the wheel speed sensor 24 is accommodated in the 5-core coaxial cable 90 through the output signal line 90d, and is connected to the ground through a resistor 87 provided in the ECU 8.

  8 is a cross-sectional view in which the cross-sectional direction in FIG. 2 is orthogonal to the cross-sectional direction of the cross-sectional view shown in FIG. 3, and FIG. 9 is a cross-sectional view of the main part including the wheel speed sensor 24 in FIG. The wheel speed sensor 24 is arranged on the wheel side, and is opposed to a ring-shaped encoder 73 in which NS magnetic poles shown in FIG. ), The knuckle 54 in the vicinity of the bearing 72 is fixed by screws. On the other hand, the brake torque sensor 20 is provided on a caliper bracket 58 disposed in the vicinity of the bearing 72.

  Therefore, if the brake torque sensor 20 and the wheel speed sensor 24 are arranged close to each other and the 5-core coaxial cable 90 is branched in the vicinity of the bearing 72, the branch cable length can be shortened and the brake torque sensor 20 The 5-core coaxial cable 90 can be optimally arranged without being affected by the mutual positions of the wheel speed sensors 24. Further, since the 5-core coaxial cable 90 is used in common, the cost can be reduced.

  FIG. 10 is a functional block diagram for estimating the temperature of the friction pads 68 and 70 of the ECU 8. The friction material temperature estimation means includes heat generation energy calculation means 100, heat radiation energy calculation means 102, rotor accumulated energy calculation means 104, and pad temperature. Calculation means 106 is provided. In the present embodiment, the temperature of the friction pads 68 and 70 is estimated for each of the wheels 16FL, 16FR, 16RL, and 16RR. However, since the processing contents are the same, the description for each of the wheels 16FL, 16FR, 16RL, and 16RR is omitted. .

  FIG. 11 is a heat dissipation equivalent circuit diagram. In this heat radiation equivalent circuit, the friction pads 68 and 70 are in contact with the brake disk (rotor) 52 and heat is generated by friction between the friction pads 68 and 70 and the rotor 52, so the temperature of the friction pads 68 and 70 is It is assumed that it is equal to the temperature of the rotor 52.

  Since the heat generation source corresponding to the current source is the friction between the friction pads 68 and 70 and the rotor 52, the heat generation energy calculation means 100 calculates the heat generation energy [W] by the equation (1).

Heat generation energy = ω × Mb (1)
ω is a wheel angular velocity [rad / s] calculated by the angular velocity calculating means from the wheel speed detected from the wheel speed sensor 24. If the wheel speed is v (m / sec), ω = v / r (r is the radius of the wheel 16). Mb is a brake torque [N · m] detected by the brake torque sensor 20 and corrected based on the temperature detected by the thermistor 22.

  The heat generation energy Ebrk [J] generated at the sampling time ts is calculated from the equation (2). The sampling time ts is a period for estimating the temperature of the friction pads 68 and 70.

Ebrk = ω × Mb × ts (2)
The heat energy accumulated in the rotor 52 is radiated from the rotor 52 to the surrounding atmosphere, so that the heat energy accumulated in the rotor 52 is reduced and the temperature of the rotor 52 is lowered. The heat radiation from the rotor 52 includes heat radiation by convection and heat radiation by radiation. The heat radiation by radiation is determined by the temperature difference between the temperature of the rotor 52 and the ambient temperature, and does not depend on other parameters. Further, in the heat radiation by convection, when the vehicle body 2 moves, the amount of ventilation to the rotor 52 changes, and when the vehicle speed increases, the amount of ventilation increases and the amount of heat radiation from the rotor 52 to the surroundings increases. That is, the amount of heat released from the rotor 52 to the surroundings varies depending on the vehicle speed.

  Accordingly, the amount of heat released from the rotor 52 is a function of the vehicle speed. Assuming that there is no slip of the wheel 16, the vehicle speed and the wheel rotation speed are equal, and the heat radiation from the rotor 52 is a function of the wheel rotation speed.

  The heat radiation heat resistance of the rotor 52 at each wheel rotation speed is calculated or calculated by experiment, and the relationship between the wheel rotation speed and the heat radiation heat resistance [° C / W] including heat radiation by radiation is stored in a memory or the like. Keep it. Note that the heat dissipation thermal resistance of the rotor 52 is a temperature difference between the rotor 52 and the surroundings, which is required for the rotor 52 to dissipate 1 W of heat.

  The heat radiation energy calculating means 102 calculates the heat radiation amount from the rotor 52 per second from the equation (3).

Heat release from rotor 52 [W] = (Tp (n−1) −Ta (n−1)) / θrot
(3)
However, Tp (n-1) is the temperature of the rotor 52 calculated at the sampling time (n-1) one sampling period ts before the current time n, and Ta (n-1) is the time (n-1). , And is equal to the temperature Ts detected by the thermistor 22 at time (n−1). θrot [° C / W] is a heat dissipation thermal resistance of the rotor 52 that combines heat dissipation by convection and heat dissipation by radiation, and is stored in the memory. The radiant heat resistance stored in this memory is stored in accordance with the ventilation rate depending on the wheel speed.

  And the thermal radiation energy Eout [J] from the rotor 52 in sampling time ts is calculated from Formula (4).

Eout = (Tp (n−1) −Ta (n−1)) × ts / θrot (4)
The rotor accumulated energy calculation means 104 and the brake 18 are in an inoperative state, and are accumulated in the rotor 52 from the time when the ignition switch is turned on to a state equal to the ambient temperature around the friction pads 68 and 70, for example. The energy Erot (n) [J] is calculated from the equation (5).

Erot (n) = Erot (n−1) + Ebrk−Eout (5)
When thermal energy is stored in the rotor 52, the temperature of the rotor 52 increases according to the stored energy Erot [n] and the heat capacity MASSrot [J / K]. The heat capacity MASSrot of the rotor 52 is heat energy required to raise the rotor 52 by 1K, and is determined by the volume of the rotor 52, specific heat, and the like.

  The pad temperature calculation means 106 calculates the current temperature Tp (n) of the friction pads 68 and 70 from equation (6).

Tp (n) = Erot (n) / MASSrot + Ta (1) (6)
Erot [n] / MASSrot is the temperature rise of the rotor 52 from when Erot = 0 by the stored energy Erot (n) of the rotor 52 to the present. Ta (1) is the temperature of the rotor 52 when Erot = 0, that is, the initial temperature of the friction pads 68 and 70, and the friction pads 68 and 70 are equal to the ambient temperature, for example, the ignition switch is This is the temperature Ts of the friction pads 68 and 70 detected by the thermistor 22 at the time of turning on.

  FIG. 12 is a flowchart showing a method for estimating the temperature of the friction pads 68 and 70. Hereinafter, a method for estimating the temperature of the friction pads 68 and 70 will be described with reference to this drawing. In step S2, it is determined whether or not the friction pads 68 and 70 are equal to the ambient temperature, for example, whether an ignition switch is turned on. If the determination is affirmative, the process proceeds to step S4. If the determination is negative, the process proceeds to step S6.

  In step S4, the temperature Ts indicated by the thermistor 22 is substituted for the pad temperature Tp and the pad initial temperature Tp (1), and zero is substituted for the rotor accumulated energy Erot to set an initial value. In step S6, it is determined whether or not the timer has been started. If the determination is affirmative, the process proceeds to step S8, and if the determination is negative, the process proceeds to step S12.

  In step S8, a timer is started. The timer activation period is the sampling time ts. In step S10, the outside air temperature is saved by substituting the temperature Ts detected by the thermistor 22 into the outside air temperature Ta. In step S12, it is determined whether or not a timer has timed out. If the determination is affirmative, the process proceeds to step S14, and if the determination is negative, the process ends.

  In step S14, the heat generation energy Ebrk = ω × Mb × ts of the rotor 52 at time ts is calculated. ω and Mb are the same as those in the formula (1).

  In step S16, the heat radiation energy Eout = (Tp−Ta) × ts / θrot of the rotor 52 at the sampling time ts is calculated. Tp is the calculated temperature of the rotor 52 before one sampling time ts. θrot is the same as that in equation (4). As a result, the heat dissipation from the rotor 52 to the surroundings is calculated not only while the brake 18 is inactive and the rotor 52 is not generating heat, but also while the brake 18 is in operation and the rotor 52 is generating heat. .

  In step S18, the rotor accumulated energy Erot = Erot + Ebrk−Eout is calculated. In step S20, pad temperature Tp = Erot / MASSrot + Tp (1) is calculated. MASSrot is the same as that in equation (6). Steps S2 to S20 are repeatedly executed at a constant cycle.

  Thus, since the temperature of the friction pads 68 and 70 is estimated based on the brake torque detected by the brake torque sensor 20 and the outside air temperature detected by the thermistor 22 instead of the brake fluid pressure, the friction pad temperature is accurately estimated. be able to.

  Further, even when the friction torque of each wheel is different due to uneven wear or one-sided friction pad, and the friction temperature of each wheel is different, the friction temperature of each wheel can be accurately measured. Further, the thermistor 22 is provided in the brake torque sensor 20, and the ambient temperature around the brake 20 can be detected by the thermistor 22, so that the amount of cooling due to heat radiation from the brake 20 can be accurately calculated, and the friction is accurately detected. The temperature of the pads 68 and 70 can be estimated.

  The initial value Tp (1) may be updated with the outside air temperature at that time when the friction pads 68 and 70 are predicted to be equal to the outside air temperature. For example, when the braking force is not exerted for a certain period of time as when traveling on an expressway, the energy Erot accumulated in the rotor 52 is dissipated to the surroundings, and the temperature of the rotor 52 is reduced by cooling the rotor 52. Becomes equal to the outside temperature.

  As described above, by appropriately updating the initial value Tp (1) when the friction pads 68 and 70 are predicted to be equal to the outside air temperature, the accumulated error of the temperature estimation is reduced, and the accuracy of the temperature estimation is further improved. be able to.

  In the present embodiment, the case where the brake is a disc brake has been described, but in the case of a drum brake as well, if the brake drum is used as a brake element, the equivalent circuit and equations (1) to (6) shown in FIG. In the case of the brake drum, the temperature of the friction material attached to the brake shoe can be estimated in the same manner as in the case of the brake disc.

  According to the present embodiment, since the connection between the brake torque sensor 20 and the wheel speed sensor 24 and the ECU 8 is connected by the single 5-core coaxial cable 90 sharing the power supply line, the 5-core coaxial cable 90 is optimal. It can be arranged. Further, since the 5-core coaxial cable 90 is used in common, the cost can be reduced and the number of man-hours for assembly and maintenance can be reduced.

1 is a schematic configuration diagram of a vehicle system to which the present invention is applied. It is a figure for demonstrating a brake torque sensor. It is a figure for demonstrating a brake torque sensor. It is a figure for demonstrating a brake torque sensor. It is a figure which shows the characteristic of a brake torque sensor. It is a figure which shows the wiring of a brake torque sensor and a wheel speed sensor. It is a figure which shows the structure of a brake torque sensor and a vehicle speed sensor. It is a figure which shows arrangement | positioning of a vehicle speed sensor. It is principal part sectional drawing of FIG. It is a functional block diagram which concerns on the friction material temperature estimation of ECU. It is the equivalent circuit schematic which concerns on the energy storage and discharge | release of a rotor. It is a flowchart which shows the friction pad temperature estimation method.

Explanation of symbols

8 ECU
10 Brake fluid pressure control device 16FL, 16FR, 16RL, 16RR Wheel 18FL, 18FR, 18RL, 18RR Brake 20FL, 20FR, 20RL, 20RR Brake torque sensor 22FL, 22FR, 22RL, 22RR Thermistor 24FL, 24FR, 24RL, 24RR Wheel speed sensor 90 5-core coaxial cable 54 Knuckle 68, 70 Friction material 100 Heat generation energy calculation means 102 Heat radiation energy calculation means 104 Meter accumulated energy calculation means 106 Pad temperature calculation means

Claims (2)

A brake device comprising: a rotation support body that rotatably supports a wheel and is spring-supported by a vehicle body by a suspension; a brake element that rotates together with the wheel; and a friction material that contacts the brake element and brakes the brake element. A temperature estimation device for the friction material,
A brake torque sensor provided at a site where distortion occurs due to brake torque during braking of the unsprung member of the suspension, and having a strain detection means and a thermistor;
Wheel rotation angular velocity detection means for detecting the rotation angular velocity of the wheel;
Friction material temperature estimation means for estimating the temperature of the friction material based on the brake torque detected by the brake torque sensor, the wheel rotation angular speed detected by the wheel rotation angular speed detection means, and the temperature detected by the thermistor;
An apparatus for estimating the temperature of a friction material.   The friction material temperature estimation means is based on the friction between the friction material and the brake element based on the brake torque detected by the brake torque sensor and the wheel rotation angular speed detected by the wheel rotation angular speed detection means. Based on the heat generation energy calculating means for calculating the heat generation energy generated, and the heat radiation resistance which is the temperature difference between the brake element and the atmosphere necessary to radiate the temperature detected by the thermistor and the heat quantity of the brake element in unit heat quantity A heat dissipation energy calculating means for calculating heat dissipation energy to the atmosphere due to a temperature difference between the temperature of the brake element and the atmosphere of the heat accumulated in the brake element, and the brake element based on the heat generation energy and the heat dissipation energy. Stored energy calculating means for calculating stored energy to be stored; A friction material temperature calculating means for estimating a temperature of the friction material based on a heat capacity of the brake element, which is energy necessary for raising the rugie and the brake element by 1 ° C. The friction material temperature estimation device according to claim 1.

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