JP6811101B2 - Electric parking brake device and brake device - Google Patents

Description

The present invention relates to an electric parking brake device and a brake device, and in particular, an electric parking brake device and a brake that drive a brake pad to brake a disc rotor by a power transmission mechanism that converts a rotational motion of an electric motor into a linear motion. It is about the device.

The electric motor drive type parking brake device amplifies the rotational torque generated by the electric motor attached to the caliper by a reduction mechanism, and further amplifies this rotational torque by a rotation / linear motion conversion mechanism such as a feed screw mechanism. It is configured to convert into motion, push out the caliper piston by the thrust of this linear motion, and press the brake pad against the disc rotor to generate braking force.

Such an electric parking brake device is described in, for example, DE102006052810A1 (Patent Document 1). In Patent Document 1, the estimation parameters used in the thrust estimation model are obtained based on the current flowing through the electric motor, the applied voltage, and the rotation speed. For example, at least torque constants, viscosity coefficients, etc. are required for the thrust estimation model as estimation parameters. Then, the thrust is estimated by the thrust estimation model using these estimation parameters, and the electric parking brake device is controlled.

DE102006052810A1

By the way, in Patent Document 1, the torque constant (φ) is estimated in the current decrease section after the power is turned on, and the viscosity coefficient (η) is estimated in the current constant section. Therefore, if the constant current section is short, the viscosity coefficient (η) may not be estimated, and the rotation of the motor may not be stable due to the change in viscosity. This causes a problem that the thrust cannot be estimated accurately.

An object of the present invention is to provide an electric parking brake device capable of accurately obtaining at least the estimation parameters used in the thrust estimation model and accurately estimating the thrust by the thrust estimation model.

The feature of the present invention is to include a cut-off current threshold value calculation unit that controls the thrust of the piston, and to reduce the current before reaching a constant current section in which the current after the inrush current generated when the electric motor is energized becomes substantially constant. Estimated parameters used in the thrust estimation model by measuring at least the voltage value and current value applied to the motor multiple times within the section and performing a predetermined calculation using these multiple voltage values and current values. Is estimated, and the cutoff current threshold is calculated by the cutoff current threshold calculation unit using these estimation parameters.

According to the present invention, it is possible to accurately estimate and calculate the estimation parameters of the thrust estimation model within the current decrease section before reaching the current constant section, and it is possible to accurately estimate the thrust by the thrust estimation model.

It is a block diagram of the electric parking brake device to which this invention is applied. It is sectional drawing which shows the structure of the brake caliper shown in FIG. It is explanatory drawing explaining the operation of the electric parking brake device. It is a control block diagram of an electric parking brake device. It is explanatory drawing explaining the current at the time of starting an electric motor, the motor terminal voltage, and the inductance voltage drop. It is explanatory drawing explaining the timing to execute the estimation calculation of the estimation parameter which becomes the embodiment of this invention. It is a control block diagram of the electronic control means which becomes embodiment of this invention. It is operation explanatory figure at the time of estimating resistance R. It is a flowchart of the control step which estimates resistance R. It is an operation explanatory drawing at the time of estimating a torque constant φ. It is a flowchart of the control step which estimates the torque constant φ. It is an operation explanatory drawing at the time of estimating the combined friction torque T _Ross during a free running period. It is a flowchart of the control step which estimates the combined friction torque T _Ross during a free running period.

The embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments, and various modifications and applications thereof are also included in the technical concept of the present invention. It is included in the range.

Hereinafter, the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of the electric parking brake device. The electric parking brake device includes an electric motor, a speed reduction mechanism, a rotation / linear motion conversion mechanism, a piston, a brake pad, and electronic control means.

In FIGS. 1 and 2, the electric parking brake device includes a brake caliper 10 that provides a braking function, and a hydraulic chamber 12 is formed inside the caliper main body 11 that constitutes the brake caliper 10. A piston 13 is arranged in the hydraulic chamber 12, and the piston 13 has a function of driving the first brake pad 14. A second brake pad 15 is attached to one end of the caliper body 11, and a disc rotor 16 fixed to the axle is arranged between the first brake pad 14 and the second brake pad 15. The disc rotor 16 is sandwiched between the first brake pad 14 and the second brake pad 15 and braked.

The piston 13 arranged in the hydraulic chamber 12 is driven by the oil pressure from the hydraulic system MB, is connected to the hydraulic pipe 34A from the booster 33A, and is thrust to the piston 13 by operating the brake pedal 17. Is a structure that causes. Then, when the brake pedal 17 is operated during normal running, the oil pressure is supplied to the hydraulic chamber 12, the piston 13 moves to the left in FIG. 2, and the first brake pad 14 is pressed against the disc rotor 16. It performs braking operation. It should be noted that this hydraulic braking operation does not operate while the vehicle is parked or stopped.

The piston 13 is connected to the deceleration mechanism 19 via a rotation / linear motion conversion mechanism 18. As shown in FIG. 2, the rotary / linear motion conversion mechanism 18 uses a sliding screw, and is screwed onto a rotary shaft 20 having a spiral screw surface formed on the outer circumference and a screw surface of the rotary shaft 20. It is composed of a linear motion member 21 having a threaded surface inside. The linear motion member 21 is separable from the piston 13, and the linear motion member 21 can move the piston 13 in the axial direction of the rotary shaft 20 by the rotation of the rotary shaft 20.

Further, in the present embodiment, the rotation / linear motion conversion mechanism 18 is provided with a self-locking function unit, and if the rotary shaft 20 is rotated, the linear motion member 21 moves linearly, but the rotation of the rotary shaft 20 is performed. When stopped, the linear motion member 21 maintains its position even if a force acts on the linear motion member 21 in the linear motion direction. That is, the rotating shaft 20 and the linear motion member 21 have a spiral threaded surface having a leading angle smaller than the friction angle, thereby obtaining a self-locking function. Since the rotation / linear motion conversion mechanism using this kind of screw surface is well known, detailed description thereof will be omitted.

As shown in FIG. 1, the rotating shaft 20 is fixed to the large-diameter gear 22 of the reduction mechanism 19, and the large-diameter gear 22 meshes with the small-diameter gear 23. The small-diameter gear 23 is rotated by the electric motor 24, and the rotation of the electric motor 24 is transmitted to the small-diameter gear 23 and the large-diameter gear 22 to reduce the speed. When the large-diameter gear 22 is rotated, the rotational torque of the electric motor 24 is amplified and transmitted to the rotating shaft 20.

The supply of electric power to the electric motor 24 is controlled by the electronic control means 25 including the electric motor control function unit, and the electric motor control function unit includes a well-known microprocessor, an output circuit, and the like. As shown in FIG. 1, the electronic control means 25 controls a relay 27 for energizing / shutting off the battery 26, an H-bridge circuit 28 for applying a voltage to the electric motor 24, and each circuit element (not shown). The microprocessor 29, the current monitor circuit 30 that detects the current flowing through the electric motor 24, the upper arm voltage monitor circuit 31 and the lower arm voltage monitor circuit 32 that detect the upper and lower arm voltages applied to the electric motor 24, and the power supply voltage. It is composed of a monitor circuit 33 and the like.

Then, when the vehicle is parked or stopped, a predetermined current is passed from the electronic control means 25 to the electric motor 24 to rotate the electric motor 24, and this rotation rotates the rotating shaft 20 via the gears 23 and 22 of the reduction mechanism 19. It is a thing. When the rotating shaft 20 rotates, the linear motion member 21 and the piston 13 move to the left side, and the first brake pad 14 is pressed against the disc rotor 16 with a predetermined thrust (pressing force) to apply braking (parking brake).

Then, the electronic control means 25 stops energization when a current is passed through the electric motor 24 to a predetermined current value (= a predetermined thrust), but when the energization of the electric motor 24 is stopped, it directly moves with the rotating shaft 20. The self-locking function section between the members 21 holds this predetermined thrust and keeps braking the disc rotor 16.

FIG. 3 shows the behavior of thrust and current during an operation of applying thrust to the piston 13 of the brake caliper 10 constituting the electric parking brake device (hereinafter, referred to as an apply operation).

In FIG. 3, at time T1 (voltage application start time), a voltage is applied to the winding of the electric motor 24 together with an operation command, but since the electric motor 24 is in a stopped state immediately after the voltage is applied, the induced voltage at this time is It is "0". After that, an inrush current (IR) is generated in which the current rapidly increases according to the time constant due to the electric resistance and the inductance.

Then, the rotation of the electric motor 24 starts just before the inrush current (IR) reaches the maximum value, but since the induced voltage is generated by the rotation of the electric motor 24, the current decreases from the increase as shown by the current (ID). After a while, the current value becomes almost constant and settles at time T2 as shown by the current (IC). During this time T1 to T2, there is a current reduction section. At this time T2, the rotation speed of the electric motor 24 also reaches almost constant.

Next, from time T2, the piston 13 moves in the direction of clamping the disc rotor 16, but the brake pads 14 and 15 have not yet sandwiched the disc rotor 16 and the clamping has not started. At this time, the thrust of the piston 13 is "0", and the current is constant during the times T2 to T3. It should be noted that this "constant current section" can include a fluctuation state permitted in terms of control, and means a section that can be regarded as substantially constant in terms of control. Therefore, although it is described as "constant current section" below, it includes a fluctuation state that is allowed from the control point of view.

Next, when the brake pads 14 and 15 sandwich the disc rotor 16 and the constant current section ends at time T3, thrust is generated in the piston 13 from time T3. As the thrust increases, the rotational torque and current of the electric motor 24 increase. In order to stop the drive of the electric motor 24 at the target thrust (F ₁ ), the microprocessor 29 calculates the cutoff current threshold ( _ISL ) from the target thrust (F ₁ ) and flows through the winding of the actual electric motor 24. The actual current value and the cutoff current threshold ( _ISL ) are compared.

After confirming that the actual current value exceeds the cutoff current threshold value ( _ISL ) at time T4 and is surely exceeded, the voltage application is stopped at time T5 to cut off the current. Therefore, the thrust is increased by this amount as compared with the time T4. Then, the time between T3 and T5 is a clamp section. At this time, at time T5, the terminals of the electric motor 24 are short-circuited in order to prevent the electric motor 24 from continuing to rotate due to the inertia of the rotor.

End clamp section, in the state in which the voltage to the electric motor 24 is not applied, it is held the target force F _1. This prevents the electric motor 24 from rotating even when pushed from the piston 13 side by using a rotation / linear motion conversion mechanism 18 having reverse operation (low reverse efficiency). After this time T5, the thrust holding section is set.

As explained above, it can be understood that the holding thrust (≈target thrust F ₁ ) in the thrust holding section is controlled by the cutoff current threshold ( _ISL ). Here, the relationship between the cutoff current threshold and the holding thrust changes depending on factors such as temperature, individual hardware differences, and voltage, and even if the holding thrust varies due to these factors, it is necessary to stop the vehicle. The minimum holding thrust must be guaranteed.

If the holding thrust falls below the minimum guaranteed thrust, the car parked on the slope may start moving without permission. In order to prevent this, the holding thrust is calculated under many assumed conditions, and the cutoff current value is determined so that the minimum value in the variation distribution of the holding thrust exceeds the minimum guaranteed thrust. On the other hand, the maximum value is a factor that reduces the durability due to excessive stress applied to the mechanical system of the electric parking brake device because an excessive thrust is generated depending on the individual having good mechanical efficiency and motor characteristics.

Therefore, it is necessary to suppress excessive variation of the holding thrust toward the upper limit while ensuring the minimum guaranteed thrust. In other words, if the thrust can be estimated accurately, the actual thrust can be adjusted between the minimum guaranteed thrust and the permissible upper limit thrust. For this purpose, it is important to accurately obtain the estimation parameters of the thrust estimation model.

Further, in the estimation of both the torque constant (φ) and the viscosity coefficient (η), the information of the rotation speed (ω) of the electric motor detected by the rotation sensor is used for the calculation. Therefore, there is a problem that the unit price of the product is increased by mounting the rotation sensor, and it is important to deal with this problem.

FIG. 4 shows a block of a control model of the electric parking brake device. The control model mainly consists of components of a battery 26, a master cylinder 35, an electronic control means 25 including a microprocessor 29 and peripheral circuits, a harness 34, an electric motor 24, and a caliper 10. Explaining the main connection relationship and input / output signals of these components, the microprocessor 29 is based on the current, voltage, and hydraulic pressure information of the master cylinder 35 of the electric motor 24, and the switch in the electronic control means 25 ( An On / Off command is issued to a relay or the like to turn the voltage output of the battery 26 on / off.

The applied voltage is applied to the electric motor 24 via the harness 34 to rotationally drive the electric motor 24. The rotational torque generated by the electric motor 24 is input to the caliper 10, the rotational torque of the electric motor 24 input in the caliper 10 is amplified by the reduction mechanism 19, and the piston 13 is amplified via the rotation / linear motion conversion mechanism 18. The thrust is output to. Further, the caliper 10 is also provided with a hydraulic action by the master cylinder 35.

Then, the equation of motion and the circuit equation can be derived for such a control model. In this embodiment, the equation of motion and the circuit equation as shown below are derived based on the main elements expressing the operation of the electric parking brake device described above.

First, the equations of motion of the clamp section from the time T3 to the time T5 shown in FIG. 3 are expressed as equations (1) and (2).

Here, in Eq. (1), "Jdω / dt" is the inertial resistance, "J" is the inertial coefficient, "φ" is the torque constant, "I" is the current, "η" is the viscosity coefficient, and "ω" is the rotation. The speed, "T _fric " is the total friction torque from the electric motor 24 to the rotation / linear motion conversion mechanism 18 of the power transmission mechanism, and "T _CLP " is the torque conversion value of the thrust. The viscosity coefficient "η", the torque constant "φ", and the friction torque "T _fric " are estimation parameters for estimating the thrust to be obtained in the present embodiment.

Further, (1) "K _B" in the formula corresponds to a rotation / linear motion conversion efficiency of the rotating / linear motion conversion mechanism 18, due to the total friction coefficient, etc. caused by the rotation / linear motion converting mechanism in the clamp section. Incidentally, the operation when applied in the present embodiment, the "K _B" is set to any value. For example, I try to enter a value that can be obtained empirically. However, as shown below, the " _TCLP " corresponding to the thrust is "0" in the idle section, so when estimating the estimation parameters (viscosity coefficient, torque constant, friction torque) in the idle section, " K _B "can be ignored.

Further, in the equation (2), "F _CLP " is the thrust applied to the piston 13, and "K" is the rotation / linear motion conversion coefficient. Therefore, the torque conversion value "T _CLP " can be obtained by multiplying the thrust "F _CLP " by the rotation / linear motion conversion coefficient "K". Here, the rotation / linear motion conversion coefficient “K” is determined by the structure of the rotation / linear motion conversion unit, but it does not need to be treated as a variation factor.

Here, the equation of motion of the free running section is expressed as Eq. (3) because the thrust (torque conversion value) of Eq. (1) is T _CLP = 0.

The circuit equation of the electric motor is expressed as Eq. (4).

Here, in the equation (4), "V" is a voltage, "R" is a winding resistance, and "L" is an inductance.

Next, parameter estimation and thrust calculation based on these equations of motion and circuit equations will be described. As described above, the relationship between the current, voltage, and thrust in the idle section was obtained by Eqs. (3) and (4). At that time, since these equations include unknown parameters, it is necessary to estimate the unknown parameters.

Unknown parameters are included in the equations shown in equations (3) and (4) of the electric parking brake device described above. Then, to summarize the circuit equation of Eq. (4) in this, the right side of the circuit equation consists of three terms of resistance voltage drop (RI), inductance voltage drop (LdI / dt), and induced voltage (ωφ). Since the term of does also include unknown coefficients and unknown variables, it is difficult to solve it exactly, but if there is an element that can be omitted from these three terms, it can be solved approximately.

Here, focusing on the electrical characteristics of the transient current, the motor terminal voltage, and the inductance voltage drop at the time of starting the electric motor 24 shown in FIG. 5, it was found that the inductance voltage drop and the induced voltage can be omitted. As shown in FIG. 5, the inductance voltage reaches its peak at the same time when the electric motor 24 is energized, but by the time it rapidly decreases within a few ms and the current value reaches the maximum value, the inductance voltage is sufficiently small. It has become. Further, since the electric motor gradually increases the rotation speed from the stopped state, the induced voltage (motor terminal voltage) is relatively small in the period of several ms immediately after the start.

From these facts, at the time of starting the electric motor 24, that is, at the start of the apply operation, the terms of inductance voltage drop (LdI / dt) and induced voltage (ωφ) in the circuit equation shown in Eq. If it can be ignored, the electrical resistance (R) is approximately obtained as shown by the following equation (5). It should be noted that this electric resistance (R) is necessary for obtaining the induced voltage (ωφ = V−RI) used in the equation (6) shown below.

Then, since the resistance (R) can be obtained by the equation (5), the induced voltage (ωφ) can be obtained by the equation (4) (the inductance voltage drop (LdI / dt) can be ignored). Here, the equation of motion is as shown in Eq. (6) so that the induced voltage (ωφ) can be used by multiplying the equation of motion shown in Eq. (3) by the torque constant (φ). It is a modified equation. This makes it possible to omit the use of rotation information from the rotation sensor. Since this equation (6) is expressed using the measured values of three discretely measured times, it is in the form of a determinant.

Next, the equation (6) will be described. First, the estimation of the torque constant (φ), the viscosity coefficient (η), and the friction torque (T _fric ) will be described using the equation (3). Equation (3), which is the equation of motion of the idle running section obtained above, includes three unknown parameters of torque constant (φ), viscosity coefficient (η), and friction torque (T _fric ). Therefore, it is necessary to formulate three equations in order to solve the three unknown parameters. Then, in the present embodiment, three equations are established in the current reduction section before reaching the current constant section in which the current value becomes substantially constant.

That is, as shown in FIG. 6, first, the electric resistance (R) is estimated and calculated from the voltage (V) and the current (I) from the start of voltage application to the time when the inrush current reaches the maximum value. This corresponds to the start-up of the electric motor 24 described by the equation (5).

Immediately after the subsequent inrush current (IR) reaches the maximum value, sampling Sp1 at time t1 and sampling Sp2 at time t2 are performed at predetermined time intervals within the current reduction section in which the current (ID) decreases. Sampling Sp3 is executed at time t3, and the voltage (V) and the current (I) are measured. Therefore, by formulating the equations of motion for three different times within the current reduction section, the equations of motion become three, and the above-mentioned three unknown parameters can be solved.

Here, since the voltage (V) and the current (I) are detected in the current decrease section before reaching the current constant section in which the current value becomes substantially constant, when the current constant section is short as in Patent Document 1. There is no fear that the viscosity coefficient (η) cannot be estimated, and this makes it possible to accurately estimate the thrust.

Further, since the voltage (V) and the current (I) are measured in the current reduction section, the amount of change in the measured value between each time becomes large, and the torque constant (φ) and the viscosity finally estimated are large. The estimation accuracy of the coefficient (η) and the friction torque (T _fric ) is _improved .

Then, when three equations of motion are set for each sampling Sp1 to Sp3 and expressed in a matrix format, they can be expressed by the following equation (6). Here, in order to distinguish the equations of motion at the times of each sampling Sp1 to Sp3, the time "t1" is for sampling Sp1, the time "t2" is for sampling Sp2, and the time is "t2" for sampling Sp3. The symbols "t3" are added to distinguish them. Further, as described above, the induced voltage (ωφ) in Eq. (6) can be obtained by ignoring the inductance voltage drop (LdI / dt) from Eq. (4) and performing the calculation of ωφ = V-RI. ..

Then, since the column vectors "φ ² ", "η", and "T _fric φ" on the right side of Eq. (6) are unknown estimation parameters, the inverse matrix is used to solve the unknown estimation parameters (7). ) Is expressed as an equation.

Here, it may be assumed that the inertial coefficient “J” does not vary, and is input as a known value. Then, from the induced voltage (ωφ) and current (I) shown on the right side of Eq. (7), the torque constant (φ), viscosity coefficient (η), and friction torque (T _fric ), which are unknown estimated parameters on the left side, are _obtained. be able to. In this case, the torque constant (φ) can be obtained from the square root of “φ ² ” on the left side, and the friction torque (T _fric ) can be obtained by dividing “T _fric φ” by the torque constant (φ). In this way, the torque constant (φ), viscosity coefficient (η), and friction torque (T _fric ) of the _{idle section} can be accurately _obtained from the voltage (V) and current (I) using the equation (7). become able to.

Next, the estimated thrust (F _CLP ) from _Eqs . (1) and (2) can be expressed by Eq. (8). Therefore, since the torque constant (φ), viscosity coefficient (η), and friction torque (T _fric ) are estimated from Eq. (7), the estimated thrust (F _CLP ) is calculated using Eq. (8) below. Can be done.

Here, as described above, the rotation / linear motion conversion efficiency K _B are those that can not be estimated due to the lack of equations needed to estimate. Thus, the rotation / linear motion conversion efficiency K _B in this embodiment is input as an arbitrary value.

Further, when a predetermined target thrust (F ^* _CLP ) is given, the target cutoff current threshold ( _ISL ) when interrupting the current to the electric motor 24 is obtained by modifying Eq. (8) as follows. It can be obtained by the equation (9) of. In this case, the torque constant (φ), the viscosity coefficient (η), and the friction torque (T _fric ) obtained from the equation (7) may be used.

Furthermore, when changing the required target thrust in the increasing direction, the cutoff current threshold ( _ISL ) is reset to a higher value by changing the target thrust (F ^* _CLP ) in Eq. (9) below. On the contrary, if the target thrust (F ^* _CLP ) is excessive, the cutoff current threshold ( _ISL ) may be reset to a low value. In this case, the cutoff current threshold value ( _ISL ) can be gradually corrected (increased or decreased) by a predetermined value according to the calculation cycle.

Further, instead of converting using an arithmetic expression, a table in which the thrust and the current value are associated is created in advance, and when the thrust is corrected, the table search is executed to perform the cutoff current threshold ( _ISL). ) May be obtained. According to this method, the effect of shortening the calculation time can be expected.
Thus, the torque constant (phi), viscosity coefficient (eta), since the target cutoff current threshold (I _SL) is obtained by reflecting the friction torque (T _Fric), can be managed in the correct thrust.

As described above, the parameter estimation formula shown in Eq. (7), the thrust calculation formula shown in Eq. (8), and the current threshold formula shown in Eq. (9) were derived. Next, the parameter estimation formula in Eq. (7) was derived. The flow of processing in the case of thrust control using the thrust calculation formula of Eq. (8) will be described with reference to the control block of FIG.

In FIG. 7, the only measurement parameters to be detected are voltage (V) and current (I). As a result, the rotation sensor can be omitted and the increase in the product unit price can be suppressed. Further, it is not necessary to correct the output error of the rotation sensor, and further, it is not necessary to install a fail-safe function against the failure of the rotation sensor.

The detection times of the voltage (V) and the current (I) are as shown in FIG. Therefore, by detecting the voltage (V) and the current (I) in the current decrease section before reaching the current constant section in which the current value becomes substantially constant, the viscosity coefficient or the like can be obtained in the current constant section as in Patent Document 1. Since such estimation parameters are not estimated, the thrust can be estimated accurately. Furthermore, since the voltage (V) and the current (I) are measured in the current reduction section, the amount of change in the measured value between each time becomes large, and the torque constant (φ) and viscosity finally estimated are large. The estimation accuracy of the coefficient (η) and the friction torque (T _fric ) is _improved .

In FIG. 7, the voltage (V) and the current (I) are input to the resistance / induced voltage estimation unit 40, and when the electric motor 24 is started, the voltage (V) and the current (I) are calculated using the equation (5). We are looking for electrical resistance (R). Further, the resistance / induced voltage estimation unit 40 selects the minimum value of the obtained electric resistance (R), and the induced voltage estimation unit 41 uses the equation (4) to obtain the voltage (V) and the current (I). And the induced voltage (ωφ = V-RI) is calculated and obtained from the electric resistance (R).

The induced voltage (ωφ) and current (I) are input to the next machine parameter estimation unit 42. Here, the resistance / induced voltage estimation unit 40 has a temperature compensation function, and this temperature compensation function is based on the voltage (V), current (I), and electric resistance (R) of the electric motor 24. Since (ωφ = V-RI) is estimated, it is possible to compensate for the change in thrust due to the temperature of the electric motor 24.

The mechanical parameter estimation unit 42 estimates the torque constant (φ), the viscosity coefficient (η), and the friction torque (T _fric ). The induced voltage (ωφ) and the current (I) are input to the machine parameter estimation unit 42, and the induced voltage (ωφ) is differentiated into a differential value (dωφ / dt), which is input to the parameter estimation unit 43. .. Further, the induced voltage (ωφ) and the current (I) before being differentiated are input to the parameter estimation unit 43. These inputs are used to estimate the torque constant (φ), viscosity coefficient (η), and friction torque (T _fric ) using the parameter estimation formula in Eq. (7).

The torque constant (φ), viscosity coefficient (η), and friction torque (T _fric ) estimated by the machine parameter estimation unit 42 using the equation (7) are input to the next target cutoff current threshold value calculation unit 46. Will be done.

The target cutoff current threshold value calculation unit 46 obtains the target cutoff current threshold value ( _ISL ) based on the equation (9). The cutoff current threshold ( _ISL ) is input to the comparator 47 and compared with the actual current value, and when the actual current value exceeds the cutoff current threshold ( _ISL ), a cutoff signal is output. In this way, when the actual current value actually flowing through the electric motor 24 reaches the cutoff current threshold value ( _ISL ), the electronic control means 25 cuts off the current supplied to the electric motor 24 and thrusts it. It will shift to the holding section.

As described above, according to the present invention, a cutoff current threshold calculation model for controlling the thrust of the piston is provided, and a constant current section in which the current after the inrush current generated when the electric motor is energized becomes substantially constant. Within the current reduction section before reaching, at least the voltage value and current value applied to the electric motor are measured multiple times, and a predetermined estimation calculation is performed using these multiple voltage values and current values to cut. The estimation parameter used in the off-current threshold calculation unit is estimated, and the cut-off current threshold is calculated using this estimation parameter.

According to this, the estimation parameter of the cutoff current threshold calculation unit can be reliably estimated and calculated within the current reduction section before reaching the current constant section, and the cutoff current threshold calculation unit accurately calculates the cutoff current threshold. Can be estimated. Further, since the rotation speed information by the rotation sensor is not used for estimating these estimation parameters, the rotation sensor can be omitted.

Next, a second embodiment of the present invention will be described. Here, since FIGS. 1 to 6 are the same as those of the first embodiment, the description thereof will be omitted. Then, as in the first embodiment, the equations of motion and the circuit equations of the main components expressing the operation of the electric parking brake device can be derived.

The equation of motion of the idle section from time T1 to time T3 shown in FIG. 3 is expressed by the following equation (10).

Here, the equation of motion of the idle running section in the equation (10) is a _combination of the components related to the viscosity coefficient “η” and the friction torque “T _fric ” in the equation (3) described in the first embodiment, and the idle running. It is re-expressed by the period combined friction torque "T _Ross ".

Next, parameter estimation and thrust calculation based on these equations of motion and circuit equations will be described. As described above, the relationship between the current, voltage, and thrust in the idle section was obtained by Eqs. (10) and (4). At that time, since these equations include unknown parameters, it is necessary to estimate the unknown parameters.

The equations shown in equations (10) and (4) of the electric parking brake device described above include unknown parameters. Then, to summarize the circuit equation of Eq. (4) in this, the right side of the circuit equation consists of three terms of resistance voltage drop (RI), inductance voltage drop (LdI / dt), and induced voltage (ωφ). Since the term of does also include unknown coefficients and unknown variables, it is difficult to solve it exactly, but if there is an element that can be omitted from these three terms, it can be solved approximately.

If the inductance voltage drop (LdI / dt) can be ignored in the circuit equation shown in Eq. (4) at the start of the electric motor 24, that is, at the start of the apply operation, the following Eq. (11) As shown by, the electric resistance (R) is approximately obtained. Unlike the equation (5), the influence of the induced voltage (ωφ) can be minimized by _setting the current value to be divided as “I _max + ΔI _avr × N”.

Here, the current value (I _max ) is a current value near the peak value of the inrush current (IR), and the current change value (ΔI _avr ) is a moving average of changes in the current (ID) after the peak value of the current. The current change value and the number of times (N) are the number of samples from the start of application to the current peak value, which will be described with reference to FIG. It can be assumed that the rotation speed (ω) decreases linearly in a time sufficiently short with respect to the machine time constant (estimated from the inertial coefficient "J", friction, etc., and is not displayed in the equation). Linear approximation of change).

Therefore, the induced voltage (ωφ), which is proportional to the rotation speed (ω), also decreases linearly. Here, since the influence of the inductance voltage drop (LdI / dt) becomes small after the peak value of the current, the current change after the peak value of the current is due to the linear change of the induced voltage (ωφ). As shown in FIG. 8, the influence of the induced voltage can be corrected by calculating the current change value (ΔI _avr ) from the value after the peak value of the current and extrapolating the current value at the start of application.

In the present embodiment, the following equation (11) is calculated in the current reduction section before reaching the current constant section in which the current value becomes substantially constant.

That is, as shown in FIGS. 9 and 8, first, in step S10, the timing from the start of voltage application until the inrush current reaches the maximum value is counted.

Subsequently, the process proceeds to steps S11, S12, S13, and S14, and "ΔI _avr × N" is calculated from the moving average value (ΔI _avr ) of the time change of the current (ID) in the current decrease section, and the peak of the inrush current is calculated. From the current value (I _max ) near the value, "ΔI _avr × N", and the monitored voltage (V: preferably immediately after applying the power supply), the electrical resistance (R) is estimated and calculated as in Eq. (11). ing. This corresponds to the start-up of the electric motor 24.

Then, after calculating the calculation result of the equation (11) in step S14, the electric resistance (R) is limited by the upper and lower limit values in step S15, and the estimation process of the electric resistance (R) is completed.

In the present embodiment, since the current value near the peak value of the inrush current is used, there is an advantage that the estimation accuracy of the electric resistance (R) can be improved even if the peak current of the motor current cannot always be sampled.

Then, since the electric resistance (R) can be obtained by the equation (11), the induced voltage (ωφ) can be obtained by the equation (4). Here, by multiplying the equation of motion shown in equation (10) by the torque constant (φ), the equation of motion is modified as in equation (12) below so that the induced voltage (ωφ) can be used. .. Incidentally, as the time interval between time t1 and time t2 is sufficiently small relative to the change in the air-run period synthetic friction torque (T _Loss), it can be regarded as a constant value an empty run time synthetic friction torque (T _Loss) ..

Eliminating (T _Loss φ) from equation (12) _yields equation (13) below.

Further, when equation (13) is solved for (φ), the following equation (14) is obtained.

In the present embodiment, the equation (14) is calculated in the current decrease section before reaching the current constant section in which the current value becomes substantially constant. That is, as shown in FIGS. 11 and 10, in step S20, sampling Sp1 is executed at time t1 and sampling Sp2 is executed at time t2 at predetermined time intervals within the current reduction section in which the current (ID) decreases. Then, the voltage (V) and the current (I) are measured. Then, by proceeding to steps S21 to 22 and formulating equations of motion for at least two different times in the current reduction section, among the two unknown parameters (φ ² ) (T _Loss φ) of Eq. (12), (T _Loss φ) can be erased to solve the torque constant (φ).

In addition, since the voltage (V) and the current (I) are measured in the current reduction section, the amount of change in the measured value between each time becomes large, and the final estimated torque constant (φ) is estimated. The accuracy is high.

Further, as described above, the induced voltage (ωφ) in Eqs. (12) to (14) is calculated as “ωφ = V-RI” by ignoring the inductance voltage drop (LdI / dt) in Eq. (4). Can be obtained by doing.

Then, after calculating the calculation result of Eq. (14), the process proceeds to steps S23 to S25, limit processing is performed with the upper and lower limit values of the torque constant (φ), and the difference between the current value and the torque constant (φ) before the n0 sample. When is less than the set value, the estimation of the torque constant (φ) is completed.

Finally, (T _Loss φ) is obtained. The "T _Ross φ" can be obtained from the induced voltage (ωφ) obtained from the equation (4) and the equation obtained by multiplying the equation (10) by φ, and further divided by the torque constant (φ), the combined friction during the idle running period The torque "T _Ross " is obtained.

The estimation operation of the combined friction torque "T _Ross " during the idle running period is shown in FIGS. 12 and 13. In steps S30 and S31, it is the current reduction section (ID) that starts the estimation of the combined friction torque "T _Loss " during the idle running period. When the estimation is started, "T _Loss " gradually converges to a value close to the true value, and the change in the calculated value of the combined friction torque "T _Loss " during the idle running period becomes gradual, the combined friction torque "T _Loss " during the free running period becomes gentle. The estimation is completed. Then, in steps S32 to S34, the calculation result of the idle running period combined friction torque "T _Loss " is limited by the upper and lower limit values of (T _Loss ), and the idle running period combined friction torque "currently and n0 samples before" is limited. When the difference between the calculated values of "T _Ross " is less than or equal to the set value, the estimation of the combined friction torque "T _Loss " during the idle running period is completed.

Even in the estimation of the combined friction torque "T _Loss " during the idle running period, it is possible to manage the estimation accuracy from the converged state of the estimated values by estimating in the current reduction section. In addition, there is an advantage that it can be reliably estimated even when the stable state that can be estimated in the idle section is short, and high reliability can be achieved.

In this way, by reflecting the torque constant (φ) and the combined friction torque ( _{TL Ross} ) during the idle running period in the following equation (15), the target cutoff current threshold ( _ISL ) can be obtained, so that the thrust can be accurate. Can be managed.

Since the process of comparing the cutoff current threshold value ( _ISL ) with the actual current value and outputting the cutoff signal is the same as that of the first embodiment, the description thereof will be omitted.

In this way, when the actual current value actually flowing through the electric motor 24 reaches the cutoff current threshold value ( _ISL ), the electronic control means 25 cuts off the current supplied to the electric motor 24 and thrusts it. It will shift to the holding section.

As described above, according to the present invention, the cutoff current threshold value calculation unit for controlling the thrust of the piston is provided, and the current constant section in which the current after the inrush current generated when the electric motor is started to be energized becomes substantially constant is provided. Within the current reduction section before reaching, at least the voltage value and current value applied to the motor are measured multiple times, and a predetermined calculation is performed using these multiple voltage values and current values to create a thrust estimation model. The estimation parameters to be used are estimated, and the cutoff current threshold is calculated by the cutoff current threshold calculation unit using these estimation parameters. There is.

According to this, the estimation parameters of the thrust estimation model can be accurately estimated and calculated in the current reduction section before reaching the current constant section, and the thrust can be estimated accurately by the thrust estimation model.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

10 ... Brake caliper, 11 ... Caliper body, 12 ... Hydraulic chamber, 13 ... Piston, 14, 15 ... Brake pad, 16 ... Disc rotor, 17 ... Brake pedal, 18 ... Rotation / linear motion conversion mechanism, 19 ... Deceleration mechanism, 20 ... Rotating shaft, 21 ... Linear member, 22 ... Large diameter gear, 23 ... Small diameter gear, 24 ... Electric motor, 25 ... Electronic control means, 26 ... Battery, 27 ... Relay, 28 ... H bridge circuit, 29 ... Micro Processor, 30 ... Current monitor circuit, 31 ... Upper arm voltage monitor circuit, 32 ... Lower arm voltage monitor circuit, 33 ... Power supply voltage monitor circuit, 34 ... Harness, 35 ... Master cylinder, 40 ... Resistance / induced voltage estimation unit, 41 ... Induced voltage estimation unit, 42 ... Mechanical parameter estimation unit, 43 ... Parameter estimation unit, 46 ... Target cutoff current threshold calculation unit, 47 ... Comparer.

Claims (6)

A piston that presses the brake pad against the disc rotor, a rotation / linear motion conversion mechanism that converts the rotary motion output by the electric motor into linear motion and propels the piston, and a rotary / linear motion conversion mechanism that is provided in the rotary / linear motion conversion mechanism and operates in reverse. In an electric parking brake device provided with a self-locking function unit for suppressing the rotation of the electric motor and an electronic control means for controlling the rotation of the electric motor.
The electronic control means
In addition to being provided with a cutoff current threshold value calculation unit that controls the thrust of the piston,
Within the current reduction section before reaching the current constant section where the current after the inrush current that occurs when the electric motor is energized becomes substantially constant, at least the voltage value and the current value applied to the motor are applied a plurality of times. The cutoff current threshold value calculation unit uses these estimated parameters to estimate the estimated parameters used in the thrust estimation model by performing predetermined calculations using the plurality of the voltage values and the current values. with performing the calculation of the cut-off current threshold by,
The cutoff current threshold calculation unit is a calculation unit that obtains the cutoff current threshold using the torque constant, the viscosity coefficient, and the friction torque.
Further, the cutoff current threshold calculation unit is
With the voltage value, either in the section where the current starts to flow in the motor and the inrush current reaches the maximum value, or in the current reduction section before reaching the current constant section where the current after the inrush current becomes substantially constant. The electric resistance estimation function that obtains the electric resistance value from the current value, and
Within the current decrease section after the inrush current reaches the maximum value, an induced voltage estimation function for obtaining an induced voltage value from the electric resistance value, the current value, and the voltage value at each measurement time,
A parameter estimation function for estimating the torque constant, the viscosity coefficient, and the friction torque by performing the predetermined calculation using the induced voltage value and the current value for each measurement time.
An electric parking brake device including a thrust estimation function for inputting the torque constant, the viscosity coefficient, and the friction torque into the thrust estimation model to obtain a thrust . In the electric parking brake device according to claim 1,
The electronic control means
An electric parking brake device including a current cutoff function unit that cuts off the current flowing through the electric motor when the actual current value of the current flowing through the electric motor reaches the cutoff current threshold value. In the electric parking brake device according to claim 1,
The parameter estimation function
In the current reduction section, a deformation formula obtained by multiplying the equation of motion from the electric motor to the rotation / linear motion conversion mechanism by the torque constant is obtained, and the current value and the induced voltage for each measurement time are obtained in this deformation formula. An electric motor characterized in that the torque constant, the viscosity coefficient, and the friction torque are obtained by estimating and calculating an unknown parameter including the torque constant, the viscosity coefficient, and the friction torque by substituting the values. Parking brake device. An electric motor that powers the braking member to press it against the braked member,
After the electric motor is energized, the control device that drives the electric motor to the cutoff current threshold and
It has a braking mechanism that holds the braking of the vehicle while the braking member is pressed against the braked member when the electric motor is driven to the cutoff current threshold value.
The control device changes the cutoff current threshold value according to the voltage value of the motor and the current value of the motor during the period in which the inrush current at the start of energization of the motor decreases, and the changed cutoff In the braking device that drives the electric motor to the current threshold,
The control device is
A cutoff current threshold value calculation unit for calculating the cutoff current threshold value is provided.
Within the current reduction section before reaching the current constant section in which the current after the inrush current generated when the electric motor is energized becomes substantially constant, the voltage value applied to the motor and the current value are applied a plurality of times. The estimation parameters used in the thrust estimation model are estimated by performing a predetermined calculation using the plurality of the voltage values and the current values, and the cutoff current threshold value is used using these estimation parameters. The calculation unit calculates the cutoff current threshold and also
The cutoff current threshold calculation unit is a calculation unit that obtains the cutoff current threshold using the torque constant, the viscosity coefficient, and the friction torque.
Further, the cutoff current threshold calculation unit is
The voltage value and the said voltage value in either the section where the current starts to flow in the motor and the inrush current reaches the maximum value or the current decrease section before reaching the current constant section where the current after the inrush current becomes substantially constant. The electric resistance estimation function that obtains the electric resistance value from the current value, and
Within the current decrease section after the inrush current reaches the maximum value, an induced voltage estimation function for obtaining an induced voltage value from the electric resistance value, the current value, and the voltage value at each measurement time ,
A parameter estimation function for estimating the torque constant, the viscosity coefficient, and the friction torque by performing the predetermined calculation using the induced voltage value and the current value for each measurement time.
It is provided with a thrust estimation function for obtaining a thrust by inputting the torque constant, the viscosity coefficient, and the friction torque into the thrust estimation model.
A braking device characterized by that. In the brake device according to claim 4,
The control device uses the voltage value and the current value of the motor at at least three time points in the current reduction section where the inrush current at the start of energization of the motor decreases to obtain the cutoff current threshold. change
A braking device characterized by that. An electric motor, a deceleration mechanism that amplifies the rotational torque of the electric motor, and a rotation / linear motion conversion mechanism that converts the rotational motion output from the deceleration mechanism into linear motion and has a self-locking function unit without reverse operation. In an electric parking brake device including a piston moved by the rotation / linear motion conversion mechanism, a brake pad pressed against the disc rotor by the piston, and electronic control means for controlling the rotation of the electric motor.
The electronic control means
It is provided with a thrust estimation model that estimates the thrust of the piston, and at least within the current reduction section before reaching the current constant section in which the current after the inrush current generated when the electric motor is energized becomes substantially constant, the motor The voltage value and the current value applied to the motor are measured a plurality of times, and a predetermined calculation is performed using the plurality of voltage values and the current value to estimate the estimation parameters used in the thrust estimation model. , A thrust estimation function unit that estimates the thrust by the thrust estimation model using these estimation parameters is provided.
The thrust estimation function unit is a calculation unit that obtains the cutoff current threshold value of the electric motor using the torque constant, the viscosity coefficient, and the friction torque.
The thrust estimation function unit
The voltage value and the said voltage value in either the section where the current starts to flow in the motor and the inrush current reaches the maximum value or the current decrease section before reaching the current constant section where the current after the inrush current becomes substantially constant. The electric resistance estimation function that obtains the electric resistance value from the current value, and
Within the current decrease section after the inrush current reaches the maximum value, an induced voltage estimation function for obtaining an induced voltage value from the electric resistance value, the current value, and the voltage value at each measurement time,
A parameter estimation function for estimating the torque constant, the viscosity coefficient, and the friction torque by performing the predetermined calculation using the induced voltage value and the current value for each measurement time.
A thrust estimation function that obtains thrust by inputting the torque constant, the viscosity coefficient, and the friction torque into the thrust estimation model.
With
Further, the cutoff current threshold value is obtained based on the thrust estimated by the thrust estimation function unit, and when the actual current value of the current flowing through the electric motor reaches the cutoff current threshold value, the current flowing through the electric motor is cut off. Equipped with a blocking function
An electric parking brake device characterized by this.

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