JP2015063152A - Electric brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain a motor drive force which an operator demands while reducing a gear noise at a low cost.SOLUTION: An electric brake device includes: a brake pedal stroke quantity detection part 24 for detecting a brake pedal stroke quantity; a brake pedal stroke quantity change rate detection part 25 for detecting a brake pedal stroke quantity change rate; a drive force calculation part 22 for periodically calculating a magnitude of a motor drive force on the basis of the brake pedal stroke quantity; and a calculation period setting part 23 for setting a calculation period for calculating the magnitude of the motor drive force. The calculation period setting part 23 sets the calculation period according to the brake pedal stroke quantity change rate so that an absolute value of a difference between a currently calculated motor drive force and a previously calculated motor drive force falls within a range of an upper limit a, and thereby a motor drive force required by an operator can be obtained while a gear noise being is reduced at a low cost.

Description

  The present invention relates to an electric brake device.

  Generally, when a brake is used in a vehicle equipped with an electric brake device, the driving force generated by driving the electric motor is transmitted to the brake pad via the planetary gear to obtain the braking force. It is assumed that the sound is uncomfortable for the driver.

JP 2000-283193 A

  In the conventional motor control by the controller, as a method of reducing the above-mentioned gear noise, a limit is set on the magnitude of the change in the motor driving force that the controller instructs the motor, that is, “the motor driving force calculated this time” and “the previous time There is a method of setting an upper limit value for the difference from the “calculated motor driving force”. Here, the upper limit value means a maximum value in a range in which the gear sound does not feel uncomfortable for the driver. In the following, the upper limit value is a.

  FIG. 3 is a graph for explaining the time change of the motor driving force when a conventional controller is used. The vertical axis represents the motor driving force, the horizontal axis represents the time, and is attached in parallel with the vertical axis. The plurality of broken lines are attached such that the width between adjacent broken lines indicates the time interval of one calculation cycle of the controller. The alternate long and short dash line in the graph represents the motor driving force requested by the driver, and the solid line represents the actual motor driving force indicated by the conventional controller within the range of the upper limit value a. And as for the some arrow in the said graph, the width | variety of the vertical axis | shaft direction represents the upper limit a.

  The graph of FIG. 3 shows a state in which the solid line cannot follow the one-dot chain line. As described above, in the motor control by the conventional controller, it is understood that the actual motor driving force cannot follow the motor driving force required by the driver if the gear noise is reduced by the above-described method. Furthermore, in the graph of FIG. 3, when the actual motor driving force is made to follow without providing the upper limit value a in order to satisfy the motor driving force required by the driver, the motor driving force in one calculation cycle becomes the upper limit value a. Because it exceeds, gear noise will be generated.

  Therefore, Patent Document 1 discloses a technique for reducing vibration by operating an electric caliper driving device in a phase opposite to a vibration mode (gear sound) generated by brake torque. However, this technique requires a large manufacturing cost. Further, when a plurality of vibration modes are generated by a plurality of gears, a higher manufacturing cost is required.

  Therefore, an object of the present invention is to provide an electric brake device that can obtain a motor driving force requested by a driver while reducing gear noise at low cost.

An electric brake device according to a first invention for solving the above-described problems is
Mounted on the vehicle,
A motor that transmits a driving force calculated based on a brake pedal stroke amount to a braking member via a gear, and presses the braking member against the braked member;
A brake pedal stroke amount detector for detecting the brake pedal stroke amount;
A brake pedal stroke amount change rate detection unit that detects a brake pedal stroke amount change rate that is a change amount per unit time of the brake pedal stroke amount;
A driving force calculator that periodically calculates the magnitude of the driving force based on the brake pedal stroke amount;
A calculation cycle setting unit for setting a calculation cycle for calculating the magnitude of the driving force;
With
The calculation cycle setting unit determines the absolute value of the difference between the driving force calculated this time and the previously calculated driving force within a predetermined upper limit range according to the brake pedal stroke amount change rate. A calculation cycle is set.

An electric brake device according to a second invention for solving the above-mentioned problems is as follows.
In the electric brake device according to the first invention,
The calculation cycle setting unit, when the brake pedal stroke amount change rate when the brake pedal stroke amount increases is positive,
The upper limit when the rate of change in the brake pedal stroke amount is negative is the first upper limit,
The upper limit value when the rate of change in the brake pedal stroke amount is positive is the second upper limit value,
The first upper limit value is set to a value smaller than the second upper limit value.

An electric brake device according to a third invention for solving the above-mentioned problem is as follows.
In the electric brake device according to the first or second invention,
A vehicle speed detector for detecting the vehicle speed of the vehicle;
The calculation cycle setting unit varies the upper limit value according to the vehicle speed.

An electric brake device according to a fourth invention for solving the above-mentioned problems is as follows.
In the electric brake device according to any one of the first to third aspects,
A temperature detector for detecting the ambient temperature of the gear;
The calculation cycle setting unit varies the upper limit value according to the ambient temperature.

  According to the electric brake device according to the first aspect of the present invention, the brake pedal stroke amount change rate is set so that the absolute value of the difference between the driving force calculated this time and the driving force calculated last time is within a predetermined upper limit value range. Therefore, when the absolute value of the brake pedal stroke amount change rate is large, the calculation cycle can be set short and the motor can be driven smoothly. Therefore, it is possible to obtain the motor driving force requested by the driver while reducing gear noise at a low cost. Further, when the absolute value of the brake pedal stroke amount change rate is small, the calculation cycle can be set long, so that the load on the ECU for calculating the driving force of the motor can be reduced, and the heat generation of the ECU can be prevented and the power can be saved. .

  According to the electric brake device according to the second aspect of the present invention, when the driver releases the brake, the actual motor drive is reduced with respect to the motor drive force required by the driver while further reducing gear noise. Force can be followed.

  According to the electric brake device according to the third aspect of the present invention, when the vehicle speed is high, the motor driving force requested by the driver is reduced without adding excessive load to the device while reducing gear noise. On the other hand, the actual motor driving force can be followed.

  According to the electric brake device of the fourth invention, when the gear temperature is low, the actual motor driving force is reduced with respect to the motor driving force requested by the driver while further reducing the gear noise. Can be followed.

It is the schematic which shows the electric brake device which concerns on Example 1 of this invention. It is a graph explaining the time change of a motor drive force at the time of using the electric brake device which concerns on Example 1 of this invention. It is a graph explaining the time change of a motor drive force at the time of using the conventional controller.

  Hereinafter, an electric brake device according to the present invention will be described with reference to the drawings in the embodiments.

[Example 1]
An electric brake device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating an electric brake device according to a first embodiment of the present invention. The electric brake device according to the first embodiment of the present invention is mounted on a vehicle, and first includes a motor 14, a gear sound reduction device 21, a brake pedal stroke amount detection unit 24, and a brake pedal stroke amount change rate detection unit 25. ing. The gear sound reduction device 21 includes a driving force calculation unit 22 and a calculation cycle setting unit 23.

  The disk rotor 12 (braking member) in FIG. 1 rotates with wheels (not shown). Further, the brake pad 11 (braking member) is incorporated in the caliper 13 and is respectively disposed on the inner side and the outer side of the friction sliding surface of the disc rotor 12. Further, the electric piston 16 is in contact with the brake pad 11 and is movable in the axial direction, and has a gear (not shown) inside. The gear 15 is disposed so as to transmit the driving force of the motor 14 to the electric piston 16.

  In the brake mechanism as described above, when the driving force of the motor 14 is transmitted to the electric piston 16 via the gear 15, the electric piston 16 presses the brake pad 11 against the disc rotor 12. Then, the disc rotor 12 is braked by friction between the brake pad 11 and the friction sliding surface of the disc rotor 12.

  Here, it is assumed that the electric brake device according to the first embodiment of the present invention is provided in the brake mechanism including a plurality of gears as described above.

  The motor 14 transmits a driving force (motor driving force) calculated based on a brake pedal stroke amount, which will be described later, to the brake pad 11 via the gear 15 and presses the brake pad 11 against the disc rotor 12. is there.

  The brake pedal stroke amount detection unit 24 detects the brake pedal stroke amount.

  The brake pedal stroke amount change rate detector 25 detects a brake pedal stroke amount change rate, which is a change amount per unit time of the brake pedal stroke amount.

  The driving force calculation unit 22 periodically calculates the magnitude of the motor driving force based on the brake pedal stroke amount, and instructs the motor 14. More specifically, a predetermined upper limit value a is provided for the absolute value of the difference between the motor driving force calculated this time and the motor driving force calculated last time, and calculation is performed based on the brake pedal stroke amount within the range of the upper limit value a. The motor 14 is instructed to the motor 14 so that the actual motor driving force follows the motor driving force. The upper limit value a is the same as the upper limit value a of the prior art described above.

  The calculation cycle setting unit 23 sets a calculation cycle for calculating the magnitude of the motor driving force in the driving force calculation unit 22. More specifically, the brake pedal stroke amount change rate is set so that the absolute value of the difference between the motor driving force calculated this time in the driving force calculation unit 22 and the motor driving force calculated last time is within the range of the upper limit value a. Set the calculation cycle accordingly.

  The above-described “setting the calculation cycle according to the rate of change in the brake pedal stroke amount” is, for example, when the absolute value of the rate of change in the brake pedal stroke amount is greater than a predetermined value, the calculation cycle of the driving force calculation unit 22. Is set to be short, and if it is equal to or less than the predetermined value, the calculation cycle of the driving force calculation unit 22 is set as usual.

  “Shortly set the calculation cycle of the driving force calculation unit 22” means a time interval in which the actual motor driving force can follow the motor driving force based on the brake pedal stroke amount within the range of the upper limit value a. In (first time interval), the calculation cycle of the driving force calculation unit 22 is set, and “setting the calculation cycle of the driving force calculation unit 22 as usual” means the same time interval ( That is, the calculation cycle (predetermined calculation cycle) of the driving force calculation unit 22 is set at the second time interval). The second time interval is longer than the first time interval.

  FIG. 2 is a graph for explaining the change over time of the motor driving force when the electric brake device according to the first embodiment of the present invention is used. The vertical axis represents motor driving force, and the horizontal axis represents time. A plurality of broken lines attached in parallel with the vertical axis indicate the time interval of one calculation cycle of the driving force calculation unit 22 between adjacent broken lines. It is attached as follows. Also, the alternate long and short dash line in the graph represents the motor driving force based on the brake pedal stroke amount, and the solid line represents the actual motor driving force indicated by the driving force calculation unit 22 within the range of the upper limit value a. ing. And as for the some arrow in the said graph, the width | variety of the vertical axis | shaft direction represents the upper limit a.

  The graph of FIG. 2 shows a state where the solid line follows the one-dot chain line. That is, the actual motor driving force follows the motor driving force based on the brake pedal stroke amount. In other words, in the motor control by the electric brake device according to the first embodiment of the present invention, the motor driving force requested by the driver can be obtained while the gear noise is reduced by providing the upper limit value a.

  That is, as shown in the graph of FIG. 2, in the electric brake device according to the first embodiment of the present invention, when the absolute value of the brake pedal stroke amount change rate is larger than the predetermined value, the calculation cycle of the driving force calculation unit 22 is set. Even if the upper limit value a is provided, the motor drive force requested is set by setting a short time and instructing the motor drive force at a short time interval (for example, increasing or decreasing the motor drive force by the upper limit value a). Force can be output.

  The magnitude of the gear sound is determined by the absolute value of the difference, not the slope of the solid line in the graph of FIG. That is, if the upper limit value a is provided for the absolute value of the difference, the gear sound is reduced because the motor is driven smoothly even if the slope of the solid line in the graph of FIG. 2 increases.

  When the absolute value of the rate of change in the brake pedal stroke amount is equal to or less than the predetermined value, an extra load is not applied to the device by setting the calculation cycle as usual. Therefore, heat generation is prevented, power is saved, and manufacturing costs are reduced.

  However, the predetermined value is set to a value at which the actual motor driving force can follow the motor driving force based on the brake pedal stroke amount even when the calculation cycle of the driving force calculation unit 22 is normal. Shall.

  By the way, as described above, when the absolute value of the rate of change in the brake pedal stroke amount is larger than the predetermined value, the calculation cycle setting unit 23 sets the calculation cycle of the driving force calculation unit 22 to be short. For example, when the brake is stepped on or released abruptly, the calculation cycle of the driving force calculation unit 22 is set short.

  In practice, however, the vehicle speed is often lower when the brake is released than when the driver depresses the brake, i.e., when the rate of change in the brake pedal stroke amount is negative. Therefore, it is desirable to set the upper limit value low because the gear sound is easily heard by the driver.

  Therefore, if the brake pedal stroke amount change rate when the brake pedal stroke amount increases is positive, the calculation cycle setting unit 23 sets the brake pedal stroke when the absolute value of the brake pedal stroke amount change rate is larger than the predetermined value. When the amount change rate is negative, the upper limit value is the first upper limit value, and when the brake pedal stroke amount change rate is positive, the upper limit value is the second upper limit value, and the first upper limit value is the second upper limit value. It may be set to a value smaller than the upper limit value. Accordingly, the calculation cycle when the first upper limit value is set is shorter than the calculation cycle when the second upper limit value is set.

  Thus, in the electric brake device according to the first embodiment of the present invention, when the driver releases the brake, the actual motor is reduced with respect to the motor driving force requested by the driver while further reducing gear noise. It becomes possible to follow the driving force.

  In general, when the vehicle speed is high, surrounding sounds increase and it becomes difficult for the driver to hear gear sounds. Therefore, in order to reduce the load on the device, it is desirable to set the upper limit value high.

  Therefore, as shown in FIG. 1, the electric brake device according to the first embodiment of the present invention further includes a vehicle speed detection unit 26 that detects the vehicle speed, and the calculation cycle setting unit 23 sets the upper limit value according to the vehicle speed. It is good also as what can fluctuate.

  As for the above-mentioned “variing the upper limit value according to the vehicle speed”, for example, when the absolute value of the brake pedal stroke amount change rate is larger than the predetermined value, the upper limit value when the vehicle speed is equal to or higher than the predetermined speed. Is the third upper limit value, and the upper limit value when the vehicle speed is less than the predetermined speed is the fourth upper limit value, the third upper limit value may be larger than the fourth upper limit value. . At this time, the calculation cycle when the third upper limit value is set is longer than the calculation cycle when the fourth upper limit value is set.

  In this way, in the electric brake device according to the first embodiment of the present invention, when the vehicle speed is high, the motor requested by the driver without reducing excessive gear load while reducing gear noise. It becomes possible to make the actual motor driving force follow the driving force.

  On the other hand, since the gear 15 and the gear (not shown) inside the electric piston 16 are made of metal, the gap between the gears increases due to thermal contraction at low temperatures, and the gear noise tends to increase. It is desirable to set the upper limit value low.

  Therefore, the electric brake device according to the first embodiment of the present invention may first further include a temperature detection unit 20 that detects the temperature of the gear. In FIG. 1, the temperature detector 20 is shown as detecting the temperature of a gear (not shown) inside the electric piston, but the present embodiment is not limited to this, and the gear is not limited to this. It is good also as what detects 15 temperature. Alternatively, the ambient temperature of the gear or the temperature of the outside air (outside temperature) may be substituted, and when the outside temperature is substituted, the detection result of the conventional temperature detecting unit for detecting the outside temperature can be used together.

  Then, the calculation cycle setting unit 23 may change the upper limit value according to each temperature.

  With regard to the above-mentioned “variation of the upper limit value in accordance with the respective temperatures”, for example, when the absolute value of the brake pedal stroke amount change rate is larger than the predetermined value, the gear ambient temperature is equal to or lower than the predetermined temperature. The fifth upper limit value may be smaller than the sixth upper limit value, where the upper limit value is the fifth upper limit value and the upper limit value when the ambient temperature of the gear is higher than the predetermined temperature is the sixth upper limit value. . Accordingly, the calculation cycle when the fifth upper limit value is set is shorter than the calculation cycle when the sixth upper limit value is set.

  Thus, in the electric brake device according to the first embodiment of the present invention, when the gear temperature is low, the actual motor drive is reduced with respect to the motor drive force requested by the driver while further reducing the gear noise. It is possible to follow the force.

  In the above description, the electric brake device according to the first embodiment of the present invention is installed for the brake mechanism having the electric piston. However, the installation target of the electric brake device according to the first embodiment of the present invention is the same. It is not limited. However, the electric brake device according to the first embodiment of the present invention can be reduced at a low cost even with a gear sound generated by a plurality of gears as provided in a brake mechanism having an electric piston.

  The present invention is suitable as an electric brake device.

11 Brake pads (braking members)
12 Disc rotor (braking member)
DESCRIPTION OF SYMBOLS 13 Caliper 14 Motor 15 Gear 16 Electric piston 20 Temperature detection part 21 Gear sound reduction device 22 Driving force calculation part 23 Calculation period setting part 24 Brake pedal stroke amount detection part 25 Brake pedal stroke amount change rate detection part 26 Vehicle speed detection part

Claims (4)

Mounted on the vehicle,
A motor that transmits a driving force calculated based on a brake pedal stroke amount to a braking member via a gear, and presses the braking member against the braked member;
A brake pedal stroke amount detector for detecting the brake pedal stroke amount;
A brake pedal stroke amount change rate detection unit that detects a brake pedal stroke amount change rate that is a change amount per unit time of the brake pedal stroke amount;
A driving force calculator that periodically calculates the magnitude of the driving force based on the brake pedal stroke amount;
A calculation cycle setting unit for setting a calculation cycle for calculating the magnitude of the driving force;
With
The calculation cycle setting unit determines the absolute value of the difference between the driving force calculated this time and the previously calculated driving force within a predetermined upper limit range according to the brake pedal stroke amount change rate. An electric brake device characterized by setting a calculation cycle. The calculation cycle setting unit, when the brake pedal stroke amount change rate when the brake pedal stroke amount increases is positive,
The upper limit when the rate of change in the brake pedal stroke amount is negative is the first upper limit,
The upper limit value when the rate of change in the brake pedal stroke amount is positive is the second upper limit value,
The electric brake device according to claim 1, wherein the first upper limit value is set to a value smaller than the second upper limit value. A vehicle speed detector for detecting the vehicle speed of the vehicle;
The electric brake device according to claim 1, wherein the calculation cycle setting unit varies the upper limit value according to the vehicle speed. A temperature detector for detecting the ambient temperature of the gear;
The electric brake device according to any one of claims 1 to 3, wherein the calculation cycle setting unit varies the upper limit value according to the ambient temperature.

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