JP5069368B2 - Electric brake device - Google Patents

Description

  The present invention relates to an electric brake device that presses a brake member against a member to be braked using an electric linear actuator that converts a rotational movement of an electric motor into a linear movement to linearly drive a driven object.

  Many of the electric linear actuators that convert the rotational motion of the electric motor into linear motion to drive the driven object linearly employ a ball screw mechanism or a ball ramp mechanism as the motion conversion mechanism. In many cases, a gear reduction mechanism such as a planetary gear reduction mechanism is incorporated so that a large linear driving force can be obtained (see, for example, Patent Document 1).

  On the other hand, many hydraulic brake devices have been adopted, but in recent years, with the introduction of advanced brake control such as ABS (Antilock Brake System), these controls are performed without a complicated hydraulic circuit. Electric brake devices that can be designed in a compact manner are attracting attention. The electric brake device operates an electric motor in response to a brake pedal depression signal or the like, and incorporates an electric linear actuator as described above into a caliper body to press a brake member against a member to be braked (for example, a patent) Reference 2).

  Usually, since the electric brake device is attached under the spring of the vehicle, it is desired to be able to operate stably even under vibration from the road surface and to be designed compactly.

JP-A-6-327190 (Figs. 1 and 5) JP 2003-343620 A (FIG. 1)

  The ball screw mechanism and the ball ramp mechanism employed in the above-described conventional electric linear actuator have a certain degree of boosting function by the motion conversion mechanism along the lead screw thread and the inclined cam surface. A large boosting function as required by a brake device or the like cannot be secured. In other words, in order to increase these boosting functions, the lead angle of the screw and the inclination angle of the cam surface may be reduced, but in the case of a ball screw mechanism, the ball diameter becomes smaller if the lead angle of the screw is reduced, Load capacity decreases. Further, in the case of the ball ramp mechanism, if the inclination angle of the cam surface is reduced, a sufficient stroke for linear motion cannot be ensured.

  For this reason, in the electric linear actuator that employs these motion conversion mechanisms, the drive force is increased by incorporating a separate reduction mechanism as described above, but a gear reduction mechanism such as a planetary gear reduction mechanism is incorporated. Not only hinders the compact design of the electric linear actuator, but the gear reduction mechanism is geared to each other with a small contact area, so it can be attached to a part that receives vibration from the road surface like an electric brake device Then, there is a problem that the gear is easily damaged.

  Therefore, an object of the present invention is to provide an electric brake device that can ensure a large boosting function without incorporating a separate speed reduction mechanism.

  In order to solve the above-described problems, an electric brake device according to the present invention includes an electric linear actuator that linearly drives a brake member by converting a rotary motion of an electric motor into a linear motion, and the linearly driven brake. A plurality of planetary rollers between an outer diameter surface of a rotor shaft of the electric motor and an inner diameter surface of an outer ring member disposed on the outer diameter side of the rotor shaft in the electric brake device that presses a member against a member to be braked These planetary rollers revolve while rotating around the rotor shaft as the rotor shaft rotates, and are spirally formed on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member. Protruding ridges are provided, and circumferential grooves into which the spiral ridges are fitted at the same pitch as the spiral ridges are provided on the outer diameter surface of each planetary roller, and coincide with the axis of the planetary roller. Center position so Uses a configuration in which the planetary roller rotation is supported by the determined first thrust bearing, and the planetary roller revolution is supported by the second thrust bearing whose center position is aligned with the axis of the rotor shaft. did.

  That is, a plurality of planetary rollers are interposed between the outer diameter surface of the rotor shaft of the electric motor and the inner diameter surface of the outer ring member disposed on the outer diameter side of the rotor shaft, and each of these planetary rollers is connected to the rotor shaft. Revolving while rotating around the rotor shaft as it rotates, a spiral ridge is provided on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, on the outer diameter surface of each planetary roller, The first thrust bearing is provided with a circumferential groove in which the spiral ridges are fitted at an equal pitch with the spiral ridges, and the center position is positioned so as to coincide with the axis of the planetary roller. Supporting the rotation of the roller and supporting the revolution of the planetary roller with a second thrust bearing whose center position is positioned so as to coincide with the axis of the rotor shaft, thereby increasing the power without incorporating a separate speed reduction mechanism. To ensure functionality It was. In addition, since the planetary roller is in rolling contact with the rotor shaft and the outer ring member in a wide range, the motion can be stably converted and transmitted even if vibration is applied.

  Here, the revolution number of the planetary roller with respect to one rotation of the rotor shaft varies depending on the diameter ratio between the rotor shaft and the planetary roller, but becomes 1/2 to 1/3. It can be designed to be as small as 1/5 to 1/10 of the lead. Therefore, compared with a ball screw mechanism that can obtain a linear motion for one lead with one rotation of the screw shaft or nut, it is possible to ensure a boosting function that is 10 times or more that of the ball screw mechanism, and no separate speed reduction mechanism is required. can do.

  The spiral ridge is formed by providing a spiral groove on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, and a strip member that forms the spiral ridge is put around the spiral groove. Thus, the spiral ridges can be easily formed at low cost. The cross-sectional shape of the strip member can be a square shape or a round shape according to the cross-sectional shape of the circumferential groove of the planetary roller.

  The electric brake device of the present invention includes a plurality of planetary rollers interposed between an outer diameter surface of a rotor shaft of an electric motor and an inner diameter surface of an outer ring member disposed on the outer diameter side of the rotor shaft. Each planetary roller revolves while rotating around the rotor shaft as the rotor shaft rotates, and a spiral ridge is provided on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member. The outer circumferential surface of the roller is provided with a circumferential groove into which the spiral ridge is fitted at the same pitch as the spiral ridge, and the center position is positioned so as to coincide with the axis of the planetary roller. The rotation of the planetary roller is supported by the first thrust bearing, and the revolution of the planetary roller is supported by the second thrust bearing whose center position is positioned so as to coincide with the axis of the rotor shaft. Large increase without incorporating the speed reduction mechanism It is possible to secure the function. In addition, since the planetary roller is in rolling contact with the rotor shaft and the outer ring member in a wide range, the motion can be stably converted and transmitted even if vibration is applied.

  By providing a spiral groove on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, the spiral protrusion is formed around the spiral member that forms the spiral protrusion on the spiral groove. Spiral ridges can be easily formed at low cost.

Cutaway perspective view showing an electric linear actuator used in the electric brake device of the first embodiment a is a longitudinal sectional view of FIG. 1, b is a sectional view taken along the line IIb-IIb of a. a is a longitudinal sectional view showing an electric linear actuator used in the electric brake device of the second embodiment, and b is a sectional view taken along line IIIb-IIIb of a. 1 is a longitudinal sectional view showing an electric brake device employing the electric linear actuator of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 and FIGS. 2A and 2B show an electric linear actuator used in the electric brake device of the first embodiment. This electric linear actuator is fixed to a pair of support members 2 fitted inside one end of the outer ring member 1 so that a stator 3 of a multipolar electric motor faces in the axial direction. The rotor 6 attached to the rotor shaft 5 supported by 4 rotates between the opposed stators 3. In addition, a plurality of planetary rollers 7 are interposed between the inner diameter surface of the other end side of the outer ring member 1 and the outer diameter surface of the rotor shaft 5 with a negative gap. As it rotates, it revolves around the rotor shaft 5 while rotating. The outer diameter surface of the planetary roller 7 and the inner diameter surface of the outer ring member 1 to which the planetary roller 7 is in rolling contact with the outer diameter surface of the rotor shaft 5 are subjected to surface hardening treatment to ensure wear resistance. The surface is lubricated with highly lubricious grease.

  A spiral groove 8 is provided on the inner surface of the other end of the outer ring member 1 to which the planetary rollers 7 are in rolling contact. A strip member 9 having a square cross section is circumferentially attached to the spiral groove 8. A circumferential groove 10 having a square cross-section into which a spiral ridge formed on one inner diameter surface is fitted is provided on the outer diameter surface of each planetary roller 7 at the same pitch as the spiral ridge. Therefore, the planetary roller 7 that revolves while rotating around the rotor shaft 5 rotates linearly in the axial direction by engagement with the spiral ridge on the outer ring member 1 side.

  A thrust needle roller bearing 11 that supports the rotation of the planetary roller 7 and a thrust needle roller bearing 12 that supports the revolution of the planetary roller 7 are sequentially arranged on the end surface of each planetary roller 7 opposite to the rotor 6. The linear motion of each planetary roller 7 is transmitted to a driven object (not shown) via these thrust needle roller bearings 11 and 12. The thrust needle roller bearing 11 is aligned with the axis of each planetary roller 7, and the thrust needle roller bearing 12 is positioned at the center so as to match the axis of the rotor shaft 5. It has become.

  3A and 3B show an electric linear actuator used in the electric brake device of the second embodiment. The basic configuration of this electric linear actuator is the same as that of the first embodiment, and the spiral ridge is attached to the spiral groove 8 a provided on the outer diameter surface of the rotor shaft 5. The only difference is that the strip member 9a has a round cross section. Therefore, in this embodiment, the planetary roller 7 that revolves while rotating around the rotor shaft 5 rotates linearly by engaging with the spiral ridges on the rotor shaft 5 side.

  FIG. 4 shows the electric brake device of the first embodiment. This electric brake device is a disc brake in which a brake pad 23 as a brake member is disposed opposite to both sides of a disc rotor 22 as a member to be braked inside the caliper body 21. A linear motion actuator is incorporated, and the linear motion of each planetary roller 7 is transmitted to the mounting plate 24 of the front brake pad 23 via the thrust needle roller bearings 11 and 12. The front end side of the cylindrical portion 21a in which the electric linear actuator is incorporated is sealed with a boot 25, and the rear end side is closed with a lid 21b.

DESCRIPTION OF SYMBOLS 1 Outer ring member 2 Support member 3 Stator 4 Ball bearing 5 Rotor shaft 6 Rotor 7 Planetary roller 8, 8a Spiral groove 9, 9a Strip member 10 Circumferential groove 11, 12 Thrust needle roller bearing 21 Caliper body 21a Cylindrical portion 21b Lid 22 Disc rotor 23 Brake pad 24 Mounting plate 25 Boot

Claims (2)

In the electric brake device that includes an electric linear actuator that linearly drives the brake member by converting the rotary motion of the electric motor into a linear motion, and presses the brake member that is linearly driven against the member to be braked,
A plurality of planetary rollers are interposed between the outer diameter surface of the rotor shaft of the electric motor and the inner diameter surface of the outer ring member disposed on the outer diameter side of the rotor shaft, and each of these planetary rollers is connected to the rotor shaft. And revolves around the rotor shaft as it rotates, and spiral ridges are provided on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, on the outer diameter surface of each planetary roller. A first thrust bearing provided with a circumferential groove into which the spiral ridge is fitted at an equal pitch to the spiral ridge, and whose center position is positioned so as to coincide with the axis of the planetary roller. An electric brake device characterized in that the revolution of the planetary roller is supported by a second thrust bearing which supports the rotation of the planetary roller and is positioned so as to coincide with the axis of the rotor shaft.   The spiral ridge is provided with a spiral groove on the outer diameter surface of the rotor shaft or the inner diameter surface of the outer ring member, and a strip member that forms the spiral ridge is wound around the spiral groove. The electric brake device according to claim 1.

Images