JP2018004039A - Electric linear motion actuator and electric brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably detect a reaction force to an axial rear part which an outer ring member receives from an object when the outer ring member applies a load in an axial front part to the object, in an electric linear motion actuator which supports a carrier by an elastic member so as to be movable to an axial direction.SOLUTION: In an electric linear motion actuator, when an outer ring member 4 does not apply a load in an axial front part to an object, a preload of an elastic member 45 is applied to a friction coupling face 47, and when the outer ring member 4 applies a load in the axial front part to the object, an axial load applied to the friction coupling face 47 is reduced by an amount of a reaction force to an axial rear part. A load sensor 30 for supporting a reaction force to the axial rear part which the outer ring member 4 receives from the object via a planetary roller 13 and a carrier 14 is arranged, and the load sensor 30 is arranged so that a detection value of the reaction force is not affected even if a magnitude of a load acting on the axial front part from a snap ring 48 is changed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric linear actuator and an electric brake device using the electric linear actuator.

  Conventionally, as a brake device for a vehicle, a hydraulic brake device using a hydraulic pressure as a drive source has been often adopted. However, the hydraulic brake device uses a brake oil, and thus has a high environmental load. Also, an ABS, a stability control system is used. It is difficult to further enhance the functions such as brake assist. Therefore, an electric brake device using an electric motor as a drive source has attracted attention as means for realizing further enhancement of the function of the brake device and reduction of environmental load.

  The electric brake device includes a brake disc that rotates integrally with a wheel, a brake pad that is disposed to face the brake disc, and an electric linear actuator that linearly drives the brake pad. The brake pad is used as a brake disc. A braking force is generated by pressing.

  As an electric linear motion actuator used in such an electric brake device, for example, the one described in Patent Document 1 is known. The electric linear actuator of Patent Document 1 includes an electric motor, a rotating shaft to which rotation of the electric motor is input, a plurality of planetary rollers that are in rolling contact with the outer periphery of the rotating shaft, and the plurality of planetary rollers that rotate. The carrier has a carrier that can be revolved in a releasable manner, an outer ring member that is disposed so as to surround the plurality of planetary rollers, and a housing that accommodates the outer ring member so as to be movable in the axial direction. A spiral ridge is provided on the inner periphery of the outer ring member, and a spiral groove or a circumferential groove that engages with the spiral ridge is provided on the outer periphery of each planetary roller.

  In this electric linear actuator, when rotation of the electric motor is input to the rotation shaft, the rotation of the rotation shaft is transmitted to the planetary roller that is in rolling contact with the outer periphery of the rotation shaft, and each planetary roller rotates while rotating. Revolve around the axis. At this time, the outer ring member moves in the axial direction by the engagement of the spiral groove or circumferential groove on the outer periphery of the planetary roller and the spiral protrusion on the inner periphery of the outer ring member.

  When this electric linear actuator is used in an electric brake device, if the lead angle of the spiral protrusion on the inner periphery of the outer ring member is set large, the moving speed in the axial direction of the outer ring member becomes faster. The time it takes for the brake pad to come into contact with the brake disc is shortened and the response of the brake can be improved. However, since the load conversion rate is small, the force with which the brake pad presses the brake disc is small. There is a problem of becoming.

  On the other hand, if the lead angle of the spiral protrusion on the inner periphery of the outer ring member is set to be small, the load conversion rate increases, so that it is possible to increase the force with which the brake pad presses the brake disc when braking. However, since the moving speed of the outer ring member in the axial direction is slow, the time required for the brake pad to come into contact with the brake disk becomes long, and the response of the brake is lowered. That is, there is a conflict between increasing the response of the brake and increasing the force with which the brake pad presses the brake disc.

  Therefore, in Patent Document 1, in order to achieve both of improving the response of the brake and increasing the force with which the brake pad presses the brake disc, a load is applied according to the axial load applied to the object from the outer ring member. It proposes a structure that changes conversion rate.

  That is, the carrier is made of an elastic member so that the carrier moves relative to the rotation axis in the axial rearward direction by the reaction force in the axial rearward direction that is received when the outer ring member applies a load in the axial direction forward to the object. I support it. In addition, when the carrier is not moved relative to the rotation axis in the axial direction rearward, the carrier is frictionally coupled with the carrier so as to limit the relative rotation between the carrier and the rotation axis, and the carrier is moved rearward in the axial direction with respect to the rotation axis. In the state of relative movement, a friction coupling portion for releasing the frictional coupling with the carrier is provided on the outer periphery of the rotation shaft so as to allow relative rotation between the carrier and the rotation shaft.

  In this way, in a state in which no load is applied forward in the axial direction from the outer ring member to the object, the friction coupling portion on the outer periphery of the rotation shaft frictionally couples with the carrier, and the relative rotation between the carrier and the rotation shaft is limited. The Therefore, when rotation is input from the outside to the rotating shaft, the carrier revolves integrally with the rotating shaft, and the outer ring member moves in the axial direction with a small reduction ratio. On the other hand, in a state where an axially forward load is applied to the object from the outer ring member, the frictional coupling between the friction coupling portion on the outer periphery of the rotation shaft and the carrier is released, and relative rotation between the carrier and the rotation shaft is allowed. Therefore, when rotation is input from the outside to the rotation shaft, the planetary roller revolves while rotating, and the outer ring member moves in the axial direction with a large reduction ratio. In this way, the load conversion rate (reduction ratio) can be switched according to the axial load applied to the object from the outer ring member.

  On the other hand, as a load sensor used for an electric brake device, for example, one described in Patent Document 2 is known. The load sensor of Patent Document 2 detects the magnitude of the axially backward reaction force received by the electric linear actuator when the electric linear actuator presses the brake pad against the brake disc. The load sensor is provided so as to support an axially rearward reaction force that the outer ring member receives from the object when the outer ring member applies an axial load to the object through the planetary roller and the carrier. ing.

Japanese Patent No. 5496836 JP 2014-016307 A

  By the way, as shown in FIG. 14, the inventor of the present application moves the outer ring member 72 in the axial direction by the engagement of the circumferential groove 71 on the outer periphery of the planetary roller 70 and the spiral protrusion 73 on the inner periphery of the outer ring member 72. The planetary roller 70 and the carrier 75 receive a reaction force in the axially rearward direction that the outer ring member 72 receives from the object when the outer ring member 72 applies a load in the axial direction forward to the object. An electric linear actuator 77 that employs a load sensor 76 that is supported via a prototype is manufactured in-house. And the test which measures the correspondence of the magnitude | size of the load ahead of the axial direction loaded on a target object from the outer ring member 72 and the output of the load sensor 76 was done.

  The electric linear actuator 77 used at this time rotates a rotating shaft 78 to which rotation of an electric motor (not shown) is input, a plurality of planetary rollers 70 which are in rolling contact with the outer periphery of the rotating shaft 78, and a plurality of planetary rollers 70. A carrier 75 that can be revolved and revolved, an outer ring member 72 disposed so as to surround the plurality of planetary rollers 70, a housing 79 that accommodates the outer ring member 72 so as to be movable in the axial direction, and an inner periphery of the outer ring member 72 And a circumferential groove 71 provided on the outer periphery of each planetary roller 70.

  Further, on the outer periphery of the rotating shaft 78, a friction engagement surface 80 that restricts a relative moving range of the carrier 75 relative to the rotating shaft 78 in the axial direction, and a relative moving range of the carrier 75 relative to the rotating shaft 78 in the axial direction rearward. And a retaining ring 81 for restricting. Between the carrier 75 and the load sensor 76, an elastic member 82 that urges the carrier 75 forward in the axial direction with respect to the rotation shaft 78 is incorporated.

  Here, the friction engagement surface 80 is frictionally coupled to the carrier 75 so as to limit the relative rotation of the carrier 75 and the rotation shaft 78 in a state where the carrier 75 is not relatively moved rearward in the axial direction with respect to the rotation shaft 78. In the state where the carrier 75 is relatively moved rearward in the axial direction with respect to the rotation shaft 78, the taper surface releases the frictional coupling between the carrier 75 and the carrier 75 so as to allow relative rotation between the carrier 75 and the rotation shaft 78.

  A load sensor 76 is fixedly provided behind the carrier 75 in the axial direction. The load sensor 76 includes a flange member 83 that supports a reaction force so that the outer ring member 72 is deflected by a reaction force in the axially rearward direction received by the outer ring member 72 when the outer ring member 72 applies a load in the axial direction forward to the object. And an annular plate-like support member 84 disposed behind the flange member 83 in the axial direction, a magnetic target 85 that generates a magnetic field, and a magnetic detection unit 86 that detects the magnetic field generated by the magnetic target 85. The relative position of the magnetic target 85 and the magnetic detection unit 86 changes according to the deflection of the flange member 83, and the magnitude of the reaction force can be detected based on the magnetic field detected by the magnetic detection unit 86. Yes.

  Then, in the electric linear motion actuator 77 having the above-described configuration, a test was performed to measure the correspondence relationship between the magnitude of the axial load applied to the object from the outer ring member 72 and the output of the load sensor 76. The following problems were found.

  That is, when the magnitude of the axially forward load applied to the object from the outer ring member 72 is monotonously increased, the value of the reaction force detected by the load sensor 76 is expected to monotonously increase as the load increases. Is done.

  However, in reality, when the magnitude of the axially forward load applied to the object from the outer ring member 72 is monotonously increased, the value of the reaction force detected by the load sensor 76 as shown in FIG. Was found to decrease once and then increase.

  The reason why the value of the reaction force detected by the load sensor 76 once decreases is considered as follows.

The magnitude of the axial rearward reaction force received by the outer ring member 72 when the outer ring member 72 applies an axially forward load to the object is F _OR , and the axial load acting on the load sensor 76 from the carrier 75. The magnitude is F _C , the magnitude of the load acting axially forward from the retaining ring 81 and input to the load sensor 76 is F _SR , and the magnitude of the axial load that the support member 84 receives from the housing 79 is F _H. When the magnitude of the preload acting on the carrier 75 from the elastic member 82 in a state where the outer ring member 72 does not apply a load forward in the axial direction to the object, F _S
When F _OR ≦ F _S , F _C = F _S , F _SR = F _S -F _OR , F _H = F _OR
When F _OR > F _S , F _C = F _OR , F _SR = 0, F _H = F _OR
It becomes.

_Here, when the _{F OR} ≦ _{F S,} for the F _SR = F S _{-F OR,} when reaction force _{F OR} of the axially rearward is applied to the outer ring member 72 from the object, its reaction force F _OR minute, reduced axial load acting on the frictional engagement surface 80 from the carrier 75, along with this, because also reduce the load F _SR acting from retaining ring 81 axially forward. Moreover, the load _{F SR,} the support member of the load sensor 76 84 is elastically deformed axially forwardly.

Thus, since the load F _SR to deflect axially forwardly relative to the support member 84 of the load sensor 76 not only acts, the load F _SR is changed depending on the size of the F _OR, the outer ring member When the axially forward load applied to the object from 72 is monotonously increased, as shown in FIG. 15, a phenomenon occurs in which the value of the reaction force detected by the load sensor 76 once decreases. I found out.

  As shown in FIG. 15, once the value of the reaction force detected by the load sensor 76 is decreased, the detection value of the load sensor 76 and the magnitude of the actual reaction force do not have a one-to-one correspondence relationship. When trying to control the magnitude of the axial load based on the detected value of 76, there is a problem that the control becomes unstable.

  The problem to be solved by the present invention is that in the electric linear motion actuator in which the carrier is supported by the elastic member so as to be movable in the axial direction, when the outer ring member applies a load in the axial direction to the object, It is to be able to detect the reaction force in the axial direction rearward received from the object stably.

In order to solve the above problems, the present invention provides an electric linear actuator having the following configuration.
An electric motor;
A rotating shaft to which rotation of the electric motor is input;
A plurality of planetary rollers in rolling contact with the outer periphery of the rotating shaft;
A carrier that holds the plurality of planetary rollers in a rotatable and revolving manner;
An outer ring member disposed so as to surround the plurality of planetary rollers;
A housing for accommodating the outer ring member movably in the axial direction;
A spiral ridge provided on the inner periphery of the outer ring member;
A spiral groove or a circumferential groove that is provided on the outer periphery of each planetary roller and engages with the spiral ridge so as to move the outer ring member in the axial direction when the planetary roller revolves while rotating;
A front side locking portion provided on the outer periphery of the rotating shaft so as to restrict a relative movement range of the carrier in the axial direction relative to the rotating shaft;
A rear locking portion provided on the outer periphery of the rotary shaft so as to restrict a relative movement range of the carrier in the axial rearward direction with respect to the rotary shaft;
An elastic member that biases the carrier forward in the axial direction with respect to the rotation shaft;
When the outer ring member does not apply a load forward in the axial direction to the object, the pre-pressure of the elastic member is applied to the front locking portion,
When the outer ring member applies a load forward in the axial direction to the object, the axial load applied to the front locking portion is reduced by the reaction force in the axial direction rearward that the outer ring member receives from the object. In the electric linear actuator,
A load sensor is provided that supports, via the planetary roller and the carrier, a reaction force in the axial rearward direction that the outer ring member receives from the object when the outer ring member applies a load in the axial direction to the object.
The load sensor is provided so that the detection value of the reaction force is not affected even if the magnitude of the load acting in the axial direction forward from the rear locking portion changes.

  By doing so, even if the magnitude of the load acting in the axial direction forward from the rear locking portion changes, the detection value of the reaction force by the load sensor is not affected, so the outer ring member is axially applied to the object. It is possible to stably detect the reaction force in the axial rearward direction that the outer ring member receives from the object when a forward load is applied.

  The load sensor includes a flange member that causes deflection due to a reaction force in the axial rearward direction that the outer ring member receives when the outer ring member applies a load in the axial direction forward to the object, and an axial rearward direction of the flange member. And a magnetic target that generates a magnetic field, and a magnetic detection unit that detects the magnetic field generated by the magnetic target, the relative position of which depends on the deflection of the flange member It is possible to adopt a configuration in which one of the magnetic target and the magnetic detection unit is fixed to the flange member and the other is fixed to the support member so as to change. Further, the support member can be incorporated between the carrier and the rear locking portion so that a load acting in the axial direction from the rear locking portion is input to the support member. In this case, in order to prevent the detection value of the reaction force from being affected even if the magnitude of the load acting in the axial direction forward from the rear locking portion changes, a radius is formed on the axial side surface of the support member. It is possible to employ a configuration in which a plurality of ribs extending in the direction are formed at intervals in the circumferential direction.

  If it does in this way, since the rigidity of a support member will become high with the rib formed in the axial direction side surface of a support member, it will be prevented that a support member bends with the load to the axial direction front inputted into a support member. Therefore, even if the magnitude of the load acting axially forward from the rear side locking portion changes, the detection value of the reaction force is not affected.

  Similarly, the load sensor includes a flange member that causes deflection due to a reaction force in the axial rearward direction received by the outer ring member when the outer ring member applies a load in the axial direction forward to the object, An annular plate-like support member disposed rearward in the axial direction, a magnetic target that generates a magnetic field, and a magnetic detection unit that detects the magnetic field generated by the magnetic target, according to the deflection of the flange member A configuration in which one of the magnetic target and the magnetic detection unit is fixed to the flange member and the other is fixed to the support member so that the relative position changes can be adopted. Further, the support member can be incorporated between the carrier and the rear locking portion so that a load acting in the axial direction from the rear locking portion is input to the support member. In this case, in order to prevent the detection value of the reaction force from being affected even if the magnitude of the load acting axially forward from the rear locking portion changes, It is possible to adopt a configuration in which the load input position is the outer diameter side end of the support member.

  In this case, since the input position of the axially forward load with respect to the support member is the outer diameter side end of the support member, the support member is bent by the axially forward load input to the support member. Is prevented. Therefore, even if the magnitude of the load acting in the axial direction from the rear locking portion changes, the detection value of the reaction force is not affected.

  Further, in order to prevent the detection value of the reaction force from being affected even if the magnitude of the load acting axially forward from the rear locking portion changes, the load sensor is connected to the rear locking portion. Alternatively, it is possible to employ a configuration that is arranged on the rear side in the axial direction.

  If it does in this way, since the said load sensor is arrange | positioned in the axial direction rear side from the said back side latching | locking part, the load which acts on the axial direction front from the said back side latching | locking part is not input into the said load sensor. Therefore, even if the magnitude of the load acting in the axial direction from the rear locking portion changes, the detection value of the reaction force is not affected.

  In this case, between the first thrust bearing that allows relative rotation of the carrier and the load sensor while transmitting an axial load between the carrier and the load sensor, and between the carrier and the rear locking portion. It is possible to adopt a configuration further including a second thrust bearing that allows relative rotation of the carrier and the rear locking portion while transmitting an axial load.

  If it does in this way, it becomes possible to implement | achieve the stable detection of the reaction force by a load sensor, reducing effectively the rotational resistance of a carrier.

  For example, the front locking portion is frictionally coupled to the carrier so as to limit relative rotation of the carrier and the rotating shaft in a state where the carrier is not relatively moved rearward in the axial direction with respect to the rotating shaft. And a friction coupling surface that releases the frictional coupling between the carrier and the carrier so as to allow relative rotation between the carrier and the rotation shaft when the carrier is relatively moved axially rearward with respect to the rotation shaft.

Moreover, in this invention, the thing of the following structures is also provided together as an electric brake device using said electric linear actuator.
A brake disc that rotates integrally with the wheel;
A brake pad disposed opposite the brake disc;
An electric brake device having an electric linear motion actuator having the above-described configuration for linearly driving the brake pad.

  In the electric linear actuator according to the present invention, even if the magnitude of the load acting in the axial direction from the rear side locking portion changes, the detection value of the reaction force by the load sensor is not affected. It is possible to stably detect a reaction force in the axially rearward direction that the outer ring member receives from the object when a load in the axially forward direction is applied to the object.

Sectional drawing which shows the electrically driven linear actuator of 1st Embodiment of this invention FIG. 1 is an enlarged cross-sectional view of the vicinity of the planetary roller screw type linear motion mechanism of FIG. Sectional view along line III-III in FIG. FIG. 2 is an enlarged sectional view in the vicinity of the load sensor of FIG. Sectional view along line VV in FIG. The figure which shows the state which the taper inner peripheral surface of the carrier and the friction coupling surface of the rotating shaft were friction-coupled without the axially rearward load being applied to the carrier shown in FIG. FIG. 2 is a diagram illustrating a state in which a load in the axial direction rearward is applied to the carrier illustrated in FIG. 2 and the frictional coupling between the taper inner peripheral surface of the carrier and the friction coupling surface of the rotating shaft is released. In the electric linear actuator of the first and second embodiments, the correspondence between the magnitude of the load in the axial direction forward from the outer ring member to the object and the output of the load sensor The expanded sectional view of the vicinity of the load sensor of the electric linear actuator of 2nd Embodiment of this invention The expanded sectional view of the vicinity of the load sensor of the electric linear actuator of 3rd Embodiment of this invention In the electric linear actuator of the third embodiment, the correspondence relationship between the magnitude of the axial forward load applied to the object from the outer ring member and the output of the load sensor Sectional drawing which shows an example of the electric brake device using the electric linear motion actuator shown in FIG. The figure which looked at the electric brake device shown in FIG. 12 from the inner side Sectional drawing which shows the electric linear actuator of a comparative example In the electric linear actuator shown in FIG. 14, the relationship between the magnitude of the axially forward load applied to the object from the outer ring member and the output of the load sensor

[First Embodiment]
(Configuration of electric linear actuator)
FIG. 1 shows an electric linear actuator 1 according to a first embodiment of the present invention. The electric linear actuator 1 includes an electric motor 2, a reduction gear train 3 that reduces and transmits the rotation of the electric motor 2, and rotation input from the electric motor 2 via the reduction gear train 3. And a planetary roller screw type linear motion mechanism 5 for converting and outputting the linear motion.

  The reduction gear train 3 includes an input gear 7 fixed to the motor shaft 6 of the electric motor 2, an output gear 9 fixed to the rotating shaft 8 of the planetary roller screw type linear motion mechanism 5, and the input gear 7 and the output gear 9. An intermediate gear 10 that transmits the rotation between them, and a gear case 11 that houses these gears. The reduction gear train 3 decelerates the rotation input to the input gear 7 from the motor shaft 6 of the electric motor 2 by sequentially transmitting the input gear 7, the intermediate gear 10, and the output gear 9 having different numbers of teeth, The decelerated rotation is output from the output gear 9 to the rotary shaft 8.

  As shown in FIGS. 2 and 3, the planetary roller screw type linear motion mechanism 5 includes a rotating shaft 8 having a cylindrical surface 12 on the outer periphery, a plurality of planetary rollers 13 that are in rolling contact with the cylindrical surface 12, and the plurality of planetary planets. A carrier 14 that holds the roller 13 so that it can rotate and revolve, a hollow cylindrical outer ring member 4 that is disposed so as to surround the plurality of planetary rollers 13, and a housing 15 that accommodates the outer ring member 4 so as to be movable in the axial direction. And have. The plurality of planetary rollers 13 are arranged at intervals in the circumferential direction between the inner periphery of the outer ring member 4 and the outer periphery of the rotating shaft 8.

  Here, the direction parallel to the rotation shaft 8 is the axial direction, and the movement direction of the outer ring member 4 when the outer ring member 4 moves to the side where the protruding length of the outer ring member 4 from the housing 15 increases is the axial direction front, the outer ring When the outer ring member 4 moves to the side where the protruding length of the member 4 from the housing 15 becomes smaller, the moving direction of the outer ring member 4 is the rear side in the axial direction, the direction around the rotating shaft 8 is the circumferential direction, and the rotating shaft 8 The direction in which the distance changes is defined as the radial direction.

  As shown in FIG. 2, spiral ridges 16 are provided on the inner periphery of the outer ring member 4. The spiral ridge 16 is a ridge that extends obliquely with a predetermined lead angle with respect to the circumferential direction. On the outer circumference of each planetary roller 13, a plurality of circumferential grooves 17 that engage with the spiral ridges 16 are formed at intervals in the axial direction. The interval between the circumferential grooves 17 adjacent to each other in the axial direction on the outer circumference of each planetary roller 13 is the same as the pitch of the spiral ridges 16. Here, the circumferential groove 17 having a lead angle of 0 degree is provided on the outer periphery of the planetary roller 13, but a spiral groove having a lead angle different from that of the spiral protrusion 16 may be provided instead of the circumferential groove 17. .

  As shown in FIGS. 2 and 3, the carrier 14 includes a plurality of support pins 18 that rotatably support the planetary rollers 13, and an axial front disk 19 that holds an axial front end of each support pin 18. The axial rear disk 20 that holds the axial rear end of each support pin 18, and the axial front disk 19 and the axial rear disk 20 are passed between a plurality of circumferentially adjacent planetary rollers 13. It has the pillar part 21 to connect. The column portion 21 integrates both the disks 19 and 20 so that the axial front disk 19 and the axial rear disk 20 do not move relative to each other in either the axial direction or the circumferential direction.

  As shown in FIG. 2, the axial front disk 19 and the axial rear disk 20 are each formed in an annular shape that penetrates the rotary shaft 8. A sliding bearing 22 that is in sliding contact with the outer periphery of the rotary shaft 8 is mounted on the inner periphery of the axial rear disk 20.

  Between the inner periphery of each planetary roller 13 and the outer periphery of the support pin 18, a radial bearing 23 that supports the planetary roller 13 so as to rotate is incorporated. A thrust bearing 24 is incorporated between each planetary roller 13 and the axially rear disk 20 to support the planetary roller 13 in the axial direction in a rotatable state. An alignment seat 25 is incorporated between the thrust bearing 24 and the axial rear disk 20 so as to tiltably support the planetary roller 13 via the thrust bearing 24.

  The outer ring member 4 is supported by an inner surface of a receiving hole 26 formed in the housing 15 so as to be slidable in the axial direction. Inside the housing 15, a load sensor 30 is fixedly provided at a position away from the carrier 14 in the axial direction rearward. A thrust bearing 27 is incorporated between the carrier 14 and the load sensor 30 to support the carrier 14 from the rear side in the axial direction so that the carrier 14 can revolve. A spacer 28 for transmitting an axial load from the carrier 14 to the thrust bearing 27 is incorporated between the carrier 14 and the thrust bearing 27.

  The load sensor 30 includes a flange member 31 that generates deflection due to a reaction force in the axially rearward direction received by the outer ring member 4 when the outer ring member 4 applies an axially forward load to the object, and an axial direction of the flange member 31. It has an annular plate-like support member 32 arranged at the rear, a magnetic target 33 that generates a magnetic field, and a magnetic detection unit 34 that detects the magnetic field generated by the magnetic target 33.

  As shown in FIG. 4, the support member 32 includes an annular plate 35 disposed opposite to the rearward in the axial direction of the flange member 31, and an outer cylinder formed by connecting to the radially outer end of the annular plate 35. It has the part 36 and the inner cylinder part 37 formed by connecting to the radial direction inner end of the annular plate 35. The outer cylinder portion 36 extends axially forward from the annular plate 35 so as to accommodate the flange member 31. Further, a step portion 38 is formed on the inner periphery of the outer cylinder portion 36 to restrict the radially outer end of the flange member 31 from moving rearward in the axial direction. The support member 32 supports the outer diameter side end of the flange member 31 from the rear side in the axial direction. When a reaction force in the rearward direction in the axial direction is input to the flange member 31, the outer end in the radial direction of the flange member 31 is supported. As a fulcrum, the flange member 31 bends rearward in the axial direction.

  The inner cylinder portion 37 of the support member 32 extends axially forward from the annular plate 35 so as to face the inner circumference of the flange member 31 in the radial direction. A radial bearing 39 that rotatably supports the rotary shaft 8 is incorporated in the inner periphery of the inner cylinder portion 37. As the radial bearing 39, for example, a sintered slide bearing or a deep groove ball bearing can be adopted.

  A support protrusion 40 that protrudes inward in the radial direction and extends in the circumferential direction is formed on the rear side in the axial direction of the fitting portion with the support member 32 on the inner periphery of the housing 15. The support protrusion 40 restricts the movement of the support member 32 in the rearward direction in the axial direction by contacting the rear end portion in the axial direction of the outer cylindrical portion 36 of the support member 32. Further, the support member 32 is restricted from moving forward in the axial direction by a retaining ring 41 attached to the inner periphery of the housing 15.

  As shown in FIG. 5, a plurality of ribs 42 extending radially inward are formed on the side surface of the annular plate 35 on the rear side in the axial direction at intervals in the circumferential direction. The radially outer end of the rib 42 and the radially inner end of the support protrusion 40 are opposed to each other in the radial direction (see FIG. 4).

  As shown in FIG. 4, the magnetic target 33 and the magnetic detection unit 34 are fixed to the inner periphery of the flange member 31 so that the relative position changes according to the deflection of the flange member 31. 34 is fixed to the outer periphery of the inner cylinder portion 37. The magnetic target 33 is composed of two permanent magnets 43 whose radial direction is the magnetization direction. The two permanent magnets 43 are arranged adjacent to each other so that the north pole of one permanent magnet 43 and the south pole of the other permanent magnet 43 are aligned in the axial direction. The magnetic detection unit 34 is disposed in the vicinity of the boundary between adjacent magnetic poles of the two permanent magnets 43 so as to face the magnetic target 33 in the radial direction. As the magnetic detection unit 34, for example, a Hall IC can be used.

  When a load in the axial direction rearward is input to the flange member 31, the load sensor 30 bends in the axial rearward direction with the outer diameter side end portion as a fulcrum. The detection unit 34 is relatively displaced in the axial direction, and the output signal of the magnetic detection unit 34 is changed according to the relative displacement between the magnetic target 33 and the magnetic detection unit 34. Therefore, by knowing in advance the relationship between the magnitude of the axial load input to the flange member 31 and the output signal of the magnetic detection unit 34, it acts on the flange member 31 based on the output signal of the magnetic detection unit 34. The magnitude of the axial load to be detected can be detected.

  As shown in FIG. 2, an elastic member 45 that urges the carrier 14 forward in the axial direction with respect to the rotation shaft 8 is incorporated between the carrier 14 and the spacer 28, and further between the spacer 28 and the carrier 14. Is provided with an axial gap 46 that allows the carrier 14 to move in the axial direction.

  The elastic member 45 is formed in an annular shape that allows the rotation shaft 8 to pass therethrough. The elastic member 45 is, for example, a disc spring. A wave spring or a coil spring can be employed instead of the disc spring. When the outer ring member 4 does not apply a load forward in the axial direction to the object (that is, when a reaction force in the axially rearward direction is not applied to the carrier 14), the elastic member 45 is previously axially moved. The compressed state is adopted, and the preload is applied from the elastic member 45 to the carrier 14.

  In this embodiment, the elastic member 45 is incorporated between the carrier 14 and the spacer 28. However, the position where the elastic member 45 is incorporated may be another position as long as it is between the carrier 14 and the load sensor 30, for example, the spacer The elastic member 45 may be assembled between the thrust bearing 27 and the thrust bearing 27. The spacer 28 may be constituted by two divided bodies that can move relative to each other in the axial direction, and the elastic member 45 may be incorporated between the two divided bodies. Further, the elastic member 45 may be incorporated between the thrust bearing 27 and the load sensor 30.

  On the outer periphery of the rotating shaft 8, a friction coupling surface 47 (front side locking portion) that restricts the relative movement range of the carrier 14 relative to the rotating shaft 8 in the axial direction and an axially rearward direction of the carrier 14 relative to the rotating shaft 8. A retaining ring 48 (rear side locking portion) that restricts the relative movement range is provided.

  The friction coupling surface 47 is a tapered surface whose outer diameter increases from the rear side in the axial direction toward the front side. The inclination angle of the frictional coupling surface 47 (the angle formed by the frictional coupling surface 47 with respect to the direction parallel to the axial direction) is set in the range of 5 to 20 °.

  A tapered inner peripheral surface 49 is formed on the inner periphery of the front disk 19 in the axial direction of the carrier 14 so as to face the friction coupling surface 47 on the outer periphery of the rotary shaft 8. The inclination angle of the taper inner peripheral surface 49 (the angle formed by the taper inner peripheral surface 49 with respect to the direction parallel to the axial direction) is set in the range of 5 to 20 °. The tapered inner peripheral surface 49 is preferably formed so as to have an inclination angle equal to that of the frictional coupling surface 47.

(Operation of electric linear actuator)
An operation example of the electric linear actuator 1 will be described.

  When the motor shaft 6 of the electric motor 2 shown in FIG. 1 rotates, the rotation is decelerated by the reduction gear train 3 and transmitted to the rotating shaft 8 of the planetary roller screw type linear motion mechanism 5.

  Here, in a state where the outer ring member 4 shown in FIG. 2 does not apply a load in the axial direction forward to the object (that is, a state in which a reaction force in the axial direction rearward is not acting on the carrier 14), the elastic member 45 preload is applied to the friction coupling surface 47, and the tapered inner circumferential surface 49 of the carrier 14 is pressed against the friction coupling surface 47 on the outer circumference of the rotating shaft 8. Further, when the axial load is input from the elastic member 45 to the frictional coupling surface 47 via the carrier 14, the rotating shaft 8 is biased forward in the axial direction, and as a result, the load is applied axially forward from the retaining ring 48. Acts, and the load is input to the support member 32. At this time, as shown in FIG. 6, the taper inner peripheral surface 49 and the friction coupling surface 47 are frictionally coupled, and the relative rotation between the carrier 14 and the rotary shaft 8 is between the taper inner peripheral surface 49 and the friction coupling surface 47. This is a state limited by the frictional force. Therefore, when rotation is input to the rotating shaft 8 shown in FIG. 2, the carrier 14 revolves integrally with the rotating shaft 8, and the planetary roller 13 revolves around the rotating shaft 8 without rotating. The planetary roller 13 and the outer ring member 4 are moved relative to each other in the axial direction by the engagement of the circumferential groove 17 on the outer periphery of the planetary roller 13 and the spiral ridge 16 on the inner periphery of the outer ring member 4. Since the movement in the axial direction together with the carrier 14 is restricted, the planetary roller 13 does not move in the axial direction with respect to the housing 15, and the outer ring member 4 moves in the axial direction with respect to the housing 15.

  At this time, since the carrier 14 revolves integrally with the rotating shaft 8 and the planetary roller 13 revolves around the rotating shaft 8 without rotating, the planetary roller 13 revolves around the rotating shaft 8 while rotating. However, the revolution speed of the planetary roller 13 is relatively high. Therefore, the moving speed of the outer ring member 4 in the axial direction is increased, and the load conversion rate is reduced.

  Then, when the axially forward load starts to be applied to the object from the outer ring member 4, the axially rearward reaction force received by the outer ring member 4 is transmitted to the carrier 14 via the planetary roller 13, and the axially rearward part thereof. The axial load applied from the carrier 14 to the frictional coupling surface 47 is reduced by the reaction force. As a result, the magnitude of the axially forward load input from the retaining ring 48 to the support member 32 also decreases.

  Thereafter, when the axially forward load that the outer ring member 4 loads on the object further increases and the axially backward reaction force that the outer ring member 4 receives from the object exceeds the pre-pressure of the elastic member 45, FIG. As shown, the amount of compression of the elastic member 45 in the axial direction increases, and the carrier 14 moves relative to the rotary shaft 8 in the axial direction rearward within the range of the axial gap 46 between the carrier 14 and the spacer 28. The frictional coupling between the tapered inner peripheral surface 49 and the frictional coupling surface 47 is released, and the carrier 14 and the rotary shaft 8 are allowed to rotate relative to each other. Here, the size of the axial gap 46 between the carrier 14 and the spacer 28 is very small, and the distance that the carrier 14 can move relative to the rotating shaft 8 in the axial direction rearward is extremely short ( For example, 0.5 mm or less).

  At this time, since the planetary roller 13 shown in FIG. 2 revolves around the rotating shaft 8 while rotating, the revolving speed of the planetary roller 13 is higher than the case where the planetary roller 13 revolves around the rotating shaft 8 without rotating. Is relatively slow. Therefore, the moving speed of the outer ring member 4 in the axial direction is slowed, and the load conversion rate is increased.

  As described above, in the electric linear actuator 1, the load conversion rate is switched according to the axial load applied from the outer ring member 4 to the object. By using the electric linear actuator 1 in an electric brake device, it is possible to improve both the response of the brake and increase the pressing force of the brake, as will be described later.

  Further, when an axially forward load is applied to the object from the outer ring member 4 shown in FIG. 2, a reaction force in the axially rearward direction acts on the outer ring member 4, and the reaction force is generated by the planetary roller 13, the thrust The load sensor 30 receives the bearing 24, the carrier 14, the spacer 28, and the thrust bearing 27. And the flange member 31 of the load sensor 30 bends in the axial direction rearward by the reaction force, and the magnetic target 33 and the magnetic detection unit 34 are relatively displaced. At this time, since the output signal of the magnetic detection unit 34 changes according to the relative displacement between the magnetic target 33 and the magnetic detection unit 34, the magnitude of the axial load is detected based on the output signal of the magnetic detection unit 34. Can do.

  Here, since the axial load acting on the frictional coupling surface 47 from the carrier 14 decreases when the axially forward load applied from the outer ring member 4 to the object is monotonously increased, the retaining ring The load acting axially forward from 48 is also reduced. Therefore, the value of the reaction force detected by the load sensor 30 may decrease until the axially rearward reaction force received by the outer ring member 4 from the object exceeds the pre-pressure of the elastic member 45.

On the other hand, in the above-described embodiment, the rigidity of the support member 32 is enhanced by the ribs 42 formed on the axial side surface of the support member 32, so that the axially forward direction input from the retaining ring 48 to the support member 32. It is possible to prevent the support member 32 from being bent by the load. Therefore, even if the magnitude of the load acting forward in the axial direction from the retaining ring 48 is changed, the detection value of the reaction force by the load sensor 30 is not affected, and as shown in FIG. It is possible to prevent the value of the reaction force detected by the load sensor 30 from decreasing until the axially backward reaction force received from the load exceeds the pre-pressure of the elastic member 45. As a result, it is possible to stably detect the reaction force in the axial rearward direction that the outer ring member 4 receives from the object when the outer ring member 4 applies a load forward in the axial direction to the object. F _S 8 is the magnitude of the preload force applied from the elastic member 45 to the carrier 14 in a state where the outer ring member 4 is not a load in the axial direction forward object.

(Configuration of electric brake device)
12 and 13 show an electric brake device using the electric linear actuator 1 having the above-described configuration. The electric brake device includes a brake disc 50 that rotates integrally with a wheel (not shown), a mounting bracket 51 that is fixed to the vehicle body so as not to move in the axial direction with respect to the brake disc 50, and the mounting bracket 51. A caliper body 52 supported so as to be slidable in parallel with the axial direction of the brake disc 50, an inner side brake pad 53 and an outer side brake pad 54 disposed opposite to both sides in the axial direction of the brake disc 50, and an inner side And an electric linear actuator 1 that linearly drives the brake pad 53. A minute clearance 55 is provided between the inner brake pad 53 and the brake disc 50. The inner brake pad 53 and the outer brake pad 54 are held by the mounting bracket 51 so as to be movable in the axial direction and immovable in the circumferential direction.

  The caliper body 52 includes a claw portion 56 that faces the back surface of the outer brake pad 54 in the axial direction and an outer shell portion 57 that faces the outer diameter side of the brake disc 50. The outer shell portion 57 is formed integrally with the housing 15 of the electric linear actuator 1. The outer shell 57 of the caliper body 52 and the housing 15 of the electric linear actuator 1 may be formed separately, and both may be integrated with bolts or the like. The outer ring member 4 is disposed on the back surface of the inner side brake pad 53 so that the inner side brake pad 53 also moves together with the outer ring member 4 when the outer ring member 4 moves.

  At the end of the outer ring member 4 on the brake disc 50 side, an engagement recess 59 that engages with an engagement protrusion 58 formed on the back surface of the inner brake pad 53 is formed. The outer ring member 4 is prevented from rotating by the engagement of the engagement recess 59.

(Operation of the electric brake device)
An operation example of this electric brake device will be described.

  When applying the brake, the outer ring member 4 of the electric linear actuator 1 is moved forward in the axial direction, and the inner brake pad 53 is pushed forward in the axial direction by the outer ring member 4. At this time, until the inner brake pad 53 comes into contact with the brake disc 50, the carrier 14 is frictionally coupled to the friction coupling surface 47 of the rotating shaft 8 as shown in FIG. The outer ring member 4 moves in the axial direction at a relatively high speed. Therefore, the time required for the inner brake pad 53 to contact the brake disc 50 is short, and the response of the brake can be improved.

  Thereafter, when the inner brake pad 53 comes into contact with the brake disc 50 and an axial load is applied from the inner brake pad 53 to the brake disc 50, the carrier 14 is moved relative to the rotary shaft 8 as shown in FIG. Since the carrier 14 and the friction coupling surface 47 of the rotary shaft 8 are released relative to each other in the axial direction, the axial movement speed of the outer ring member 4 shown in FIG. Increases and generates a large axial load. Therefore, the force with which the inner brake pad 53 presses the brake disc 50 can be increased.

  As described above, when the electric linear actuator 1 is used in the electric brake device, it is possible to improve both the response of the brake and increase the force with which the inner brake pad 53 presses the brake disc 50. It becomes possible. Even when the force with which the inner brake pad 53 presses the brake disc 50 is small, the pressing force of the inner brake pad 53 can be stably controlled based on the output of the load sensor 30.

[Second Embodiment]
FIG. 9 shows a second embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A second support member 60 is provided between the support member 32 and the retaining ring 48. The second support member 60 is formed in an annular shape that penetrates the rotating shaft 8. The inner diameter side end portion of the second support member 60 is supported from the rear side in the axial direction by a retaining ring 48, and the outer diameter side end portion of the second support member 60 is axially rearward of the outer diameter side end portion of the support member 32. Support from the side. Here, the support member 32 and the second support member 60 are in contact only at the outer diameter side end, and the inner diameter side is not in contact with the support member 32 and the second support member 60. As described above, by incorporating the second support member 60 between the retaining ring 48 and the supporting member 32, the input position of the axially forward load inputted from the retaining ring 48 to the supporting member 32 can be changed to that of the supporting member 32. It is the outer diameter side end. The outer diameter side end of the second support member 60 is sandwiched between the support protrusion 40 and the retaining ring 41 in the axial direction. The second support member 60 may be formed integrally with the housing 15.

  In the electric linear actuator 1 according to the second embodiment, the input position of the load in the axial direction from the retaining ring 48 to the support member 32 is the end on the outer diameter side of the supporting member 32. The support member 32 is prevented from being bent by the axially forward load input to the support member 32. Therefore, even if the magnitude of the load acting axially forward from the retaining ring 48 changes due to the axially backward reaction force that the outer ring member 4 receives from the object, the detection value of the reaction force by the load sensor 30 has an effect. 8, the value of the reaction force detected by the load sensor 30 until the axially rearward reaction force received by the outer ring member 4 from the object exceeds the preload of the elastic member 45, as shown in FIG. 8. Can be prevented from decreasing. As a result, it is possible to stably detect the reaction force in the axial rearward direction that the outer ring member 4 receives from the object when the outer ring member 4 applies a load forward in the axial direction to the object.

[Third Embodiment]
FIG. 10 shows a third embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A retaining ring 48 (rear side locking portion) that restricts the relative movement range of the carrier 14 in the axial rearward direction with respect to the rotating shaft 8 is provided at a portion between the outer periphery of the rotating shaft 8 and the load sensor 30. ing. Here, the load sensor 30 is positioned on the rear side in the axial direction from the retaining ring 48 (rear side locking portion).

  A first thrust bearing 27 is incorporated between the spacer 28 and the flange member 31 to allow relative rotation between the carrier 14 and the load sensor 30 while transmitting an axial load between the carrier 14 and the load sensor 30. Yes. A second thrust bearing 61 is incorporated between the spacer 28 and the retaining ring 48 to allow relative rotation between the carrier 14 and the retaining ring 48 while transmitting an axial load between the carrier 14 and the retaining ring 48. It is. As the second thrust bearing 61, a sliding bearing can be adopted. However, when a rolling bearing is adopted, the rotational resistance of the carrier 14 can be more effectively reduced.

  In the electric linear actuator 1 according to the third embodiment, since the load sensor 30 is arranged on the rear side in the axial direction from the retaining ring 48, the load acting in the axial direction from the retaining ring 48 is input to the load sensor 30. Not. Therefore, even if the magnitude of the load acting axially forward from the retaining ring 48 changes, the detection value of the reaction force by the load sensor 30 is not affected, and as shown in FIG. It is possible to prevent the value of the reaction force detected by the load sensor 30 from decreasing until the axially backward reaction force received from the load exceeds the pre-pressure of the elastic member 45. As a result, it is possible to stably detect the reaction force in the axial rearward direction that the outer ring member 4 receives from the object when the outer ring member 4 applies a load forward in the axial direction to the object.

  In this case, the load sensor 30 has a friction coupling surface 47 (front side locking portion) that restricts the relative movement range of the carrier 14 relative to the rotation shaft 8 in the axial direction, and the rearward direction in the axial direction of the carrier 14 relative to the rotation shaft 8. Since it is not between the retaining rings 48 (rear side locking portions) that regulate the relative movement range, it is possible to completely prevent the force of the elastic member 45 from affecting the load sensor 30, as shown in FIG. As described above, a linear output can be obtained as the output of the load sensor 30.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Electric linear actuator 2 Electric motor 4 Outer ring member 8 Rotating shaft 13 Planetary roller 14 Carrier 15 Housing 16 Spiral protrusion 17 Circumferential groove 27 First thrust bearing 30 Load sensor 31 Flange member 32 Support member 33 Magnetic target 34 Magnetic Detection unit 42 Rib 45 Elastic member 47 Friction coupling surface 48 Retaining ring 50 Brake disc 53 Inner side brake pad 61 Second thrust bearing

Claims (7)

An electric motor (2);
A rotating shaft (8) to which rotation of the electric motor (2) is input;
A plurality of planetary rollers (13) in rolling contact with the outer periphery of the rotating shaft (8);
A carrier (14) for holding the plurality of planetary rollers (13) in a rotatable and revolving manner;
An outer ring member (4) disposed so as to surround the plurality of planetary rollers (13) and supported so as to be movable in the axial direction;
A housing (15) for accommodating the outer ring member (4) so as to be movable in the axial direction;
A spiral ridge (16) provided on the inner periphery of the outer ring member (4);
It is provided on the outer periphery of each planetary roller (13), and engages with the spiral ridge (16) so as to move the outer ring member (4) in the axial direction when the planetary roller (13) revolves while rotating. A mating spiral or circumferential groove (17);
A front locking portion (47) provided on the outer periphery of the rotating shaft (8) so as to restrict a relative movement range of the carrier (14) relative to the rotating shaft (8) in the axial direction forward;
A rear locking portion (48) provided on the outer periphery of the rotating shaft (8) so as to restrict the relative movement range of the carrier (14) in the axial rearward direction with respect to the rotating shaft (8);
An elastic member (45) for urging the carrier (14) axially forward with respect to the rotating shaft (8);
When the outer ring member (4) does not apply an axial load to the object, the preload of the elastic member (45) is applied to the front locking portion (47),
When the outer ring member (4) applies a load in the axial direction forward to the object, an amount of reaction force in the axial direction rearward that the outer ring member (4) receives from the object is applied to the front locking portion (47). In the electric linear actuator that reduces the applied axial load,
When the outer ring member (4) applies an axially forward load to the object, the planetary roller (13) and the carrier (14) receive the axially backward reaction force that the outer ring member (4) receives from the object. A load sensor (30) supported via
The load sensor (30) is provided so that the detection value of the reaction force is not affected even if the magnitude of the load acting axially forward from the rear locking portion (48) changes. An electric linear actuator characterized by that. The load sensor (30) is a flange member that generates a deflection due to a reaction force in the axial rearward direction received by the outer ring member (4) when the outer ring member (4) applies a load forward in the axial direction to the object. 31), an annular plate-like support member (32) disposed axially rearward of the flange member (31), a magnetic target (33) for generating a magnetic field, and the magnetic target (33) are generated. A magnetic detection unit (34) for detecting a magnetic field, and the magnetic target (33) and the magnetic detection unit (34) are configured such that a relative position changes according to the deflection of the flange member (31). One is fixed to the flange member (31) and the other is fixed to the support member (32),
The support member (32) includes the carrier (14) and the rear locking portion (so that the load acting in the axial direction from the rear locking portion (48) is input to the support member (32). 48),
A plurality of radially extending ribs (42) are formed on the side surface in the axial direction of the support member (32) at intervals in the circumferential direction.
The electric linear actuator according to claim 1. The load sensor (30) is a flange member that generates a deflection due to a reaction force in the axial rearward direction received by the outer ring member (4) when the outer ring member (4) applies a load forward in the axial direction to the object. 31), an annular plate-like support member (32) disposed axially rearward of the flange member (31), a magnetic target (33) for generating a magnetic field, and the magnetic target (33) are generated. A magnetic detection unit (34) for detecting a magnetic field, and the magnetic target (33) and the magnetic detection unit (34) are configured such that a relative position changes according to the deflection of the flange member (31). One is fixed to the flange member (31) and the other is fixed to the support member (32),
The support member (32) includes the carrier (14) and the rear locking portion (so that the load acting in the axial direction from the rear locking portion (48) is input to the support member (32). 48),
The input position of the axially forward load with respect to the support member (32) is the outer diameter side end of the support member (32).
The electric linear actuator according to claim 1.   The electric linear actuator according to claim 1, wherein the load sensor (30) is disposed on the rear side in the axial direction with respect to the rear locking portion (48). A first thrust bearing (27) that allows relative rotation of the carrier (14) and the load sensor (30) while transmitting an axial load between the carrier (14) and the load sensor (30);
A second thrust that allows relative rotation of the carrier (14) and the rear locking portion (48) while transmitting an axial load between the carrier (14) and the rear locking portion (48). The electric linear actuator according to claim 4, further comprising a bearing (61).   In the state where the carrier (14) is not relatively moved rearward in the axial direction with respect to the rotation shaft (8), the front locking portion (47) is formed between the carrier (14) and the rotation shaft (8). When the carrier (14) is frictionally coupled with the carrier (14) so as to limit relative rotation and the carrier (14) is relatively moved axially rearward with respect to the rotation shaft (8), the carrier (14) and the rotation The electric linear actuator according to any one of claims 1 to 5, which is a friction coupling surface (47) for releasing the frictional coupling with the carrier (14) so as to allow relative rotation of the shaft (8). A brake disc (50) rotating integrally with the wheel;
A brake pad (53) disposed opposite the brake disc (50);
The electric brake device having the electric linear motion actuator (1) according to any one of claims 1 to 6, wherein the brake pad (53) is linearly driven.

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