JP2006231954A - Electric braking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption and improve durability of an electric brake when an electric braking device is used as an electric stop brake. <P>SOLUTION: An inclined condition of a vehicle is judged by an inclination sensor while the vehicle is stopping (step S11). When the vehicle stops on an ascending road or a descending road (step S12), only electric brakes for rear wheels or electric brakes for front wheels among electric brakes installed to four wheels are actuated (step S14). When the vehicle stops on a flat road, the electric brakes of the four wheels are sequentially actuated for a predetermined time one by one (step S15). Thereby, compared to the case where all of the electric brakes are actuated, power consumption of the electric brakes can be reduced and heating can be restrained so as to heighten durability. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a front wheel electric brake for generating a braking force on a front wheel, a rear wheel electric brake for generating a braking force on a rear wheel, and a control means for controlling the operation of the front wheel electric brake and the rear wheel electric brake. It is related with the electric brake device provided with.

When the electric stopping brake of the vehicle is activated, the braking force according to the depression force of the brake pedal is used in order to avoid an increase in the power consumption of the electric brake motor due to the generation of a braking force that is more than necessary. In addition, a technique for calculating a braking force necessary for maintaining a vehicle in a stopped state from an inclination angle detected by an inclination sensor and generating the braking force by an electric brake is disclosed in Patent Document 1 below.
JP 2001-63537 A

  However, in the above-mentioned Patent Document 1, even if the braking force necessary for maintaining the vehicle in the stopped state is calculated, all the electric brakes of the four wheels are continuously operated. An increase in electric power is inevitable, and when the vehicle stops for a long time, there is a possibility that the motor of the actuator generates heat and shortens its life.

  The present invention has been made in view of the above circumstances, and an object thereof is to reduce power consumption and improve durability of an electric brake when the electric brake device is used as a stop brake.

  To achieve the above object, according to the first aspect of the present invention, a front wheel electric brake for generating a braking force on a front wheel, a rear wheel electric brake for generating a braking force on a rear wheel, and a front wheel And an electric brake device including a control means for controlling the operation of the electric brake and the electric brake for the rear wheel. The control means is configured to control the electric brake for the front wheel and the electric brake for the rear wheel according to the state of inclination of the road surface when the vehicle is stopped. An electric brake device characterized by changing the distribution ratio of the operation amount is proposed.

  According to the invention described in claim 2, the front wheel electric brake for generating the braking force on the front wheel, the rear wheel electric brake for generating the braking force on the rear wheel, the front wheel electric brake and the rear wheel electric brake. And an electric brake device including a control means for controlling the operation of the brake, wherein the control means changes a distribution ratio of the operation amounts of the electric brake for the front wheels and the electric brake for the rear wheels in accordance with an elapsed time while the vehicle is stopped. An electric brake device characterized by the above is proposed.

  The electronic control unit U of the embodiment corresponds to the control means of the present invention.

  According to the configuration of the first aspect, the control unit changes the distribution ratio of the operation amounts of the front wheel electric brake and the rear wheel electric brake according to the inclined state of the road surface when the vehicle is stopped. Compared with the case where both the rear wheel electric brakes are operated at the maximum output, the power consumption of the electric brakes can be reduced, and the durability can be enhanced by suppressing the heat generation.

  According to the configuration of the second aspect, since the control means changes the distribution ratio of the operation amounts of the front wheel electric brake and the rear wheel electric brake according to the elapsed time during the stop, the front wheel electric brake and the rear wheel Compared with the case where the electric brakes for wheels are always operated at the maximum output, the power consumption of these electric brakes can be reduced, and the durability can be enhanced by suppressing heat generation.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 10 show an embodiment of the present invention. FIG. 1 is a cross-sectional view of an electric brake having a function of an electric stop brake, FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1 is a sectional view taken along the line 3-3 in FIG. 1, FIG. 4 is a diagram for explaining the operation when the electric stop brake is operated, FIG. 5 is a diagram for explaining the operation when the electric stop brake is forcibly released, and FIG. FIG. 7 is a flowchart of a stop brake mode routine, FIG. 8 is an operation explanatory diagram when stopping on an uphill road, FIG. 9 is an operation explanatory diagram when stopping on a downhill road, and FIG. 10 is an operation when stopping on a flat road. It is explanatory drawing.

  As shown in FIGS. 1 to 3, the electric brake that can also be used as an electric stop brake includes a brake caliper 11 that is supported by a knuckle or the like so as to be movable in the left-right direction in FIG. 1. Brake pads 14a and 14b are provided on opposite surfaces of a pair of back plates 12a and 12b that are supported by guide means (not shown) so as to be able to approach and separate from each other. It is done. A brake piston 15 is supported on the main body 11a of the brake caliper 11 so as to be able to advance and retreat. The brake caliper 11 is pressed against the back surface of one back plate 12a by the brake piston 15 so that the brake caliper 11 is moved to the right in FIG. The arm portion 11c connected to the main body portion 11a of the brake caliper 11 via the bridging portion 11b presses the back surface of the other back plate 12b, so that both brake pads 14a and 14b A braking force is generated in contact with both side surfaces. A dustproof boot 16 is mounted between the brake piston 15 and the brake caliper 11.

  The electric motor M housed in the main body 11a of the brake caliper 11 includes a plurality of stator coils 17 fixed to the inner surface of the main body 11a, and a ball bearing 18 that is rotatable around the axis L inside the stator coils 17. And a plurality of permanent magnets 20 fixed to the outer peripheral surface of the motor output shaft 19 so as to face the inner peripheral surface of the stator coils 17. A cylindrical female screw member 21 is supported inside the motor output shaft 19 by a pair of ball bearings 22 and 23 so as to be relatively rotatable. Between the male screw member 24 extending integrally on the axis L from the back surface of the brake piston 15. Are arranged with a plurality of balls 25. These female screw member 21, male screw member 24 and balls 25 ... constitute a ball screw mechanism S.

  A planetary gear mechanism P is arranged inside the main body 11 a of the brake caliper 11 so as to connect the electric motor M and the ball screw mechanism S. The planetary gear mechanism P disposed on the axis L includes a sun gear 31 fixed to the motor output shaft 19, a planetary carrier 32 serving also as a ratchet wheel fixed to the female screw member 21 of the ball screw mechanism S, and an outer periphery of the planetary carrier 32. And a plurality of pinions 35 that are supported on the planetary carrier 32 via pinion shafts 34 and mesh with the sun gear 31 and the ring gear 33 at the same time. Between the planetary carrier 32 and the inner surface of the main body 11a, a thrust bearing 36 for supporting a braking reaction force that the brake piston 15 receives from the brake disk 13 is disposed.

  The planetary gear mechanism P includes three elements, that is, a sun gear 31, a planetary carrier 32 (ratchet wheel), and a ring gear 33. The sun gear 31 constituting the input element is fixed to the motor output shaft 19, of which the planetary constituting the output element. The carrier 32 is fixed to the female screw member 21 of the ball screw mechanism S via the connecting shaft 37. A ring gear 33 constituting the fixing element is fixed to the main body 11 a of the brake caliper 11. At this time, the sun gear 31 is supported on the outer periphery of the connecting shaft 37 disposed on the axis L so as to be relatively rotatable.

  The electric brake includes a ratchet mechanism R for causing it to function as an electric stop brake. The ratchet mechanism R has a ratchet pawl 42a at one end thereof, which is pivotally supported by the planetary carrier 32 (ratchet wheel) and a central portion so as to be swingable by a fulcrum pin 41 and engages with ratchet teeth 32a of the planetary carrier 32 The ratchet pawl 42, the torsion coil spring 43 that urges the ratchet pole 42 in the direction in which the ratchet pawl 42a is detached from the ratchet teeth 32a, and the one end side of the ratchet pawl 42 are pressed to push the ratchet pawl 42a into the ratchet teeth 32a. .. Are provided, and a bolt 45 capable of pressing the other end of the ratchet pole 42 is provided.

  As shown in FIGS. 8 to 10, the same type of electric brake having the above structure is mounted on the left and right front wheels WFL, WFR and the left and right rear wheels WRL, WRR. Hereinafter, the electric brakes attached to the left and right front wheels WFL and WFR are respectively indicated as BFL and BFR, and the electric brakes attached to the left and right rear wheels WRL and WRR are indicated as BRL and BRR, respectively. Signals from the vehicle speed sensor Sa and the inclination sensor Sb are input to the electronic control unit U that controls the operation of the four electric brakes BFL, BFR, BRL, and BRR.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the electric brake is used as a service brake, when the electric motor M is driven forward in accordance with the driver's brake operation, the rotation of the rotor output shaft 19 is input to the sun gear 31 of the planetary gear mechanism P, and the ring gear 33 is fixed so as not to rotate. Therefore, the rotation of the sun gear 31 is transmitted to the female screw member 21 of the ball screw mechanism S via the pinions 35..., The planetary carrier 32 and the connecting shaft 37. When the female screw member 21 rotates, the male screw member 21 engaged therewith via the balls 25... Moves forward together with the brake piston 15, and the brake piston 15 abuts the brake pads 14 a and 14 b against the brake disk 13 to generate a braking force. To do. When the electric motor M is driven in reverse, the brake piston 15 moves backward, the brake pads 14a and 14b are separated from the brake disc 13, and the braking force is released.

  When the electric brake is used as an electric stop brake, when the driver turns on the parking switch, the electric motor M rotates forward and the brake piston 15 moves forward, so that the braking force is applied in the same manner as in the case of the service brake described above. appear. When a predetermined braking force is generated, the solenoid 44 is energized, and as shown in FIG. 4, the ratchet pawl 42 pressed against the solenoid 44 resists around the fulcrum pin 41 against the elastic force of the torsion coil spring 43. By swinging clockwise, the ratchet pawl 42a of the ratchet pole 42 is engaged with the ratchet teeth 32a of the planetary carrier 32.

  When energization of the electric motor M is stopped in this state, the brake pads 14a and 14b are retracted by the reaction force received from the brake disc 13, and the planetary carrier 32 is about to rotate in the braking release direction, whereby the ratchet pole 42 is ratchet. The pawl 42a meshes strongly with the ratchet teeth 32a of the planetary carrier 32, and the electric stopping brake is kept in the operating state even when the energization of the solenoid 44 is released.

  When the driver turns off the parking switch, the electric motor M is driven in the forward rotation direction for a moment, and the planetary carrier 32 rotates slightly in the braking direction. As a result, the ratchet pawl 42a of the ratchet pole 42 is disengaged from the ratchet teeth 32a of the planetary carrier 32, and the ratchet pole 42 is rotated clockwise to the position of FIG. 3 by the elastic force of the torsion coil spring 43. Thus, the restraint of the planetary carrier 32 is released. Then, the brake pads 14a and 14b are automatically retracted by the reaction force received from the brake disc 13, and the operation of the electric stop brake is released. At this time, the electric motor M may be reversed to assist the reaction force received by the brake pads 14a, 14b from the brake disc 13.

  Now, if the electric motor M fails during the operation of the electric stop brake, the ratchet mechanism R cannot be disengaged, the electric stop brake remains operated, and the vehicle cannot run. In such a case, as shown in FIG. 5, by manually rotating the bolt 45, the ratchet pole 42 is pressed to swing clockwise around the fulcrum pin 41, and the ratchet pawl 42a of the ratchet pole 42 is moved to the planetary position. It can be forcibly separated from the ratchet teeth 32a of the carrier 32. As a result, it is possible to avoid a situation in which the operation of the electric stop brake cannot be released when the electric motor M including the failure of the power source cannot be operated.

  Next, control of the electric brakes BFL, BFR, BRL, BRR provided on the four wheels will be described with reference to FIGS.

  When it is determined in step S1 of the flowchart of FIG. 6 that the vehicle is in a stopped state based on the output of the vehicle speed sensor Sa connected to the electronic control unit U. If the stopped state continues for a predetermined time in step S2, a normal operation is performed in step S3. Transition from brake mode to stop brake mode.

  In step S11 of the flowchart of FIG. 7, the front / rear inclination state (road surface inclination state) of the parked vehicle is determined based on the output of the inclination sensor Sa connected to the electronic control unit U. In step S12, the road surface is uphill or downhill. If it is a hill road, the braking force to be generated for the four-wheel electric brakes BFL, BFR, BRL, BRR is calculated in step S13, and in step S14, the electric brakes BFL, BFR, BFR, BFR, Operate BRL and BRR.

  That is, as shown in FIG. 8, when the vehicle is stopped on the uphill road, only the electric brakes BRL and BRR of the left and right rear wheels WRL and WRR are operated, and the electric brakes BFL and BFR of the left and right front wheels WFL and WFR are operated. Does not work. The reason why the electric brakes BRL and BRR of the left and right rear wheels WRL and WRR are operated on the uphill road is that the ground load on the rear wheels WRL and WRR is increased, and the braking force is effectively generated.

  On the other hand, as shown in FIG. 9, when the vehicle is stopped on a downhill road, only the electric brakes BFL and BFR of the left and right front wheels WFL and WFR are operated, and the electric brakes BRL and BRR of the left and right rear wheels WRL and WRR are operated. Does not work. The reason why the electric brakes BFL and BFR of the left and right front wheels WFL and WFR are operated on the downhill road is that the ground load of the front wheels WFL and WFR is increased, and the braking force is effectively generated.

  Thus, by braking only the front wheels WFL, WFR or the rear wheels WRL, WRR depending on whether the vehicle is stopped on the uphill road or the downhill road, the electric brakes BFL, BFR, BRL, BRR are controlled. The frequency of use can be reduced to save power consumption, and the heat generation of the electric motor M can be suppressed to increase durability.

  Returning to the flowchart of FIG. 7, if the road is a flat road, not an uphill road or a downhill road, in step S12, as shown in FIG. 10, the electric brakes for the four wheels WFL, WFR, WRL, WRR are shown in FIG. BFL, BFR, BRL, and BRR are sequentially operated one by one at predetermined time intervals (for example, every 10 minutes).

  Also in this case, compared with the case where all of the electric brakes BFL, BFR, BRL, BRR of the four wheels WFL, WFR, WRL, WRR are operated, the use frequency is reduced and the power consumption is reduced. Heat generation can be suppressed and durability can be enhanced. In addition, when the vehicle is stopped on a flat road, it is sufficient to brake one wheel because the possibility of the vehicle moving with an external force such as gravity is low.

  Then, when the driver turns off the parking switch in step S16, the vehicle is returned from the stop brake mode to the normal brake mode in step S17.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, only the front wheels WFL, WFR, only the rear wheels WRL, WRR, or only one electric brake BFL, BFR, BRL, BRR are operated when the vehicle is stopped, but the four wheels WFL, WFR, WRL, WRR are operated. The same effect can be achieved even if the three-wheel or four-wheel electric brakes BFL, BFR, BRL, BRR are operated and the magnitude of the braking force is varied.

Cross section of electric brake with electric stop brake function 2-2 sectional view of FIG. 3-3 sectional view of FIG. Action explanatory diagram at the time of operation of electric stop brake Action explanatory diagram at the time of forced release of electric stop brake Flowchart of stop state determination routine Stop brake mode routine flowchart Action explanation diagram when stopping on the uphill road Action explanation diagram when stopping on a downhill road Action explanatory diagram when stopping on a flat road

Explanation of symbols

BFL Electric brake BFR Electric brake BRL Electric brake BRR Electric brake U Electronic control unit (control means)
WFL Front wheel WFR Front wheel WRL Rear wheel WRR Rear wheel

Claims (2)

Front wheel electric brakes (BFL, BFR) for generating braking force on the front wheels (WFL, WFR);
Rear wheel electric brakes (BRL, BRR) for generating braking force on the rear wheels (WRL, WRR);
Control means (U) for controlling the operation of the front wheel electric brakes (BFL, BFR) and the rear wheel electric brakes (BRL, BRR);
In the electric brake device with
The control means (U) changes the distribution ratio of the operation amounts of the front wheel electric brakes (BFL, BFR) and the rear wheel electric brakes (BRL, BRR) according to the state of inclination of the stopped road surface. Electric brake device. Front wheel electric brakes (BFL, BFR) for generating braking force on the front wheels (WFL, WFR);
Rear wheel electric brakes (BRL, BRR) for generating braking force on the rear wheels (WRL, WRR);
Control means (U) for controlling the operation of the front wheel electric brakes (BFL, BFR) and the rear wheel electric brakes (BRL, BRR);
In the electric brake device with
The control means (U) changes the distribution ratio of the operation amounts of the front wheel electric brakes (BFL, BFR) and the rear wheel electric brakes (BRL, BRR) according to the elapsed time while the vehicle is stopped. Electric brake device.

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