JP6909102B2 - Wave gear reducer and actuator of link mechanism for internal combustion engine - Google Patents

Description

The present invention relates to a strain wave gearing reducer and an actuator of a link mechanism for an internal combustion engine including a strain wave gearing reducer.

A small strain wave gearing reducer having a large reduction ratio has been adopted in recent years as a reduction gear for actuators of robots and industrial machines. The strain wave gearing gear reducer consists of a rigid internal gear that is a perfect circular annular member and has internal teeth inside, a flexible external gear that is arranged inside the rigid internal gear and has external teeth, and a flexible external gear. It is equipped with an elliptical wave generator fitted inside. The rigid internal gear is fixed so as not to rotate. The flexible external gear is a thin-walled cylindrical member that can be flexed and deformed, and is connected to a control shaft of an actuator. The wave generator is rotated by a drive source such as a motor. The number of teeth of the rigid internal gear is larger than the number of teeth of the flexible external gear.

As the wave generator rotates, the flexible external gear is deformed into an elliptical shape inside the rigid internal gear by the wave generator. The flexible external gear rotates relative to the rigid internal gear according to the difference in the number of teeth from the rigid internal gear by engaging the rigid internal gear and each other's teeth while deforming. By the above mechanism, the rotation of the input side (wave generator) is decelerated according to the difference in the number of teeth between the rigid internal gear and the flexible external gear.

The strain wave gearing reducer includes a flexible external gear which is a thin cylindrical member, and if an excessive torque is generated, damage such as scraping of the gear teeth may occur. To solve this problem, the strain wave gearing speed reducer described in Patent Document 1 is provided with a torque limiter mechanism that limits the torque transmitted from the wave generator to the flexible external gear by the wave generator. Avoid damage. In the wave gear reducer of Patent Document 1, the wave generator includes a rigid cam plate, a hub inserted in the center of the rigid cam plate, a torque limiter mechanism having an elastic member and a ball, and a torque limit mechanism is predetermined. When a torque exceeding the value acts on the wave gear reducer, the torque transmission is restricted by causing slippage in the rotational direction between the rigid cam plate and the hub, and damage to the wave gear reducer is avoided.

Patent Document 2 describes an example of an actuator of a link mechanism for an internal combustion engine.

Japanese Unexamined Patent Publication No. 11-118003 Japanese Unexamined Patent Publication No. 2011-169152

In the conventional strain wave gearing reducer, when the torque limiter mechanism acts to limit the transmission of torque, it takes time for the limitation of torque transmission to be lifted, and the actuator cannot be controlled for a long time. There is. For example, in the strain wave gearing gear reducer described in Patent Document 1, when the torque limiter mechanism acts, the ball moves against the elastic force of the elastic member, and slip in the rotational direction occurs between the rigid cam plate and the hub. However, it is difficult to control the actuator until the ball returns to the initial position (the position before the torque limiter mechanism operates). When a strain wave gearing reducer is used as an actuator of a link mechanism for an internal combustion engine, an excessive torque such that a torque limiter mechanism acts is generated for a moment. Therefore, it is desirable that the strain wave gearing reducer immediately returns to a state in which the actuator can be controlled as soon as the excessive torque is eliminated after the torque limiter mechanism is activated. However, in the prior art such as the technique described in Patent Document 1, this point is not taken into consideration, and there is a concern that it will take time until the actuator can be controlled.

An object of the present invention is for a strain wave gearing reducer capable of preventing damage due to the generation of excessive torque and shortening the time during which the actuator becomes uncontrollable after the excessive torque is eliminated, and for an internal combustion engine provided with this strain wave gearing reducer. It is to provide an actuator of a link mechanism.

The wave gear reducer according to the present invention has an annular shape and a rigid internal gear having a plurality of teeth on the inner peripheral surface, and a cylindrical gear having a plurality of teeth on the outer peripheral surface and arranged inside the rigid internal gear. The flexible external gear is an annular shape having an elliptical outer circumference, and is arranged inside the flexible external gear, and the outer peripheral surface slides along the inner peripheral surface of the flexible external gear. A movable wave generator, an input shaft connected to the central portion of the wave generator, and rotating the wave generator to rotate the flexible external gear, a plurality of elastic members, and the elasticity. A plurality of spherical members, each of which is fixed to one end of the member, are provided. The wave generator and the input shaft are provided with a plurality of recesses that open at a connecting surface between the wave generator and the input shaft in the circumferential direction. Each of the elastic members is installed in one of the recesses of the wave generator and the recess of the input shaft, and the spherical member is fixed to the one end on the opening side of the one recess. A part of each of the spherical members is inserted into the recess of the wave generator and the recess of the input shaft, whichever is the recess.

According to the present invention, a wave gear reducer capable of preventing damage due to the generation of excessive torque and shortening the time during which the actuator becomes uncontrollable after the excessive torque is eliminated, and a link for an internal combustion engine provided with this wave gear reducer. The actuator of the mechanism can be provided.

It is the schematic of the link mechanism for an internal combustion engine provided with the actuator by this invention. It is sectional drawing of the actuator of the link mechanism for an internal combustion engine according to Example 1 of this invention. FIG. 5 is an exploded isometric view of the strain wave gearing speed reducer according to the first embodiment of the present invention. FIG. 5 is an axial cross-sectional view of a wave generator and a motor output shaft according to a first embodiment of the present invention. FIG. 5 is a radial cross-sectional view of the wave generator and the motor output shaft at the connection position between the wave generator and the motor output shaft according to the first embodiment of the present invention. FIG. 5 is an axial cross-sectional view of a wave generator and a motor output shaft according to a second embodiment of the present invention. FIG. 5 is a radial cross-sectional view of the wave generator and the motor output shaft at the connection position between the wave generator and the motor output shaft in the second embodiment of the present invention. FIG. 5 is a radial cross-sectional view of the wave generator and the motor output shaft at the connection position between the wave generator and the motor output shaft in the third embodiment of the present invention. FIG. 3 is a diagram showing an elastic member installed in a space in a normal time when an excessive torque is not applied to a wave gear reducer in the third embodiment of the present invention. FIG. 5 is a diagram showing an elastic member installed in a space when an excessive torque is applied to a strain wave gearing reducer in the third embodiment of the present invention.

The strain wave gearing gear reducer according to the present invention includes a rigid internal gear, a flexible external gear arranged inside the rigid internal gear, a wave generator arranged inside the flexible external gear, and a wave generator. It includes an input shaft connected to the central portion of the vessel, a plurality of elastic members, and a plurality of spherical members, each of which is fixed to one end of the elastic member. The wave generator and the input shaft are provided with a plurality of recesses (grooves or recesses described in the examples) that open at the connecting surface between the wave generator and the input shaft in the circumferential direction. Each of the elastic members is installed in one of the recesses of the wave generator and the recess of the input shaft (groove portion described in the embodiment), and a spherical member is provided at one end of the one recess (groove portion) on the opening side. Is fixed. A part of each of the spherical members is inserted into the recess of the wave generator and the recess of the input shaft (the recess described in the embodiment).

A strain wave gearing gear reducer according to an embodiment of the present invention and an actuator of a link mechanism for an internal combustion engine including the strain wave gearing gear reducer will be described with reference to the drawings.

FIG. 1 is a schematic view of a link mechanism for an internal combustion engine provided with an actuator according to the present invention. The basic configuration of this link mechanism is described in, for example, Patent Document 2 (particularly FIG. 1 and its description), and will be briefly described here.

The upper end of the upper link 3 is rotatably connected to the piston 1 that reciprocates in the cylinder of the cylinder block of the internal combustion engine via the piston pin 2. A lower link 5 is rotatably connected to the lower end of the upper link 3 via a connecting pin 6. A crankshaft 4 is rotatably connected to the lower link 5 via a crank pin 4a. Further, the upper end portion of the first control link 7 is rotatably connected to the lower link 5 via a connecting pin 8. The lower end of the first control link 7 is connected to a link mechanism 9 having a plurality of link members. The link mechanism 9 is a link mechanism of an internal combustion engine, and includes a first control shaft 10, a second control shaft (actuator control shaft) 11, and a second control link 12.

The first control shaft 10 extends parallel to the crankshaft 4 extending in the cylinder row direction inside the internal combustion engine. The first control shaft 10 has a first journal portion 10a, a control eccentric shaft portion 10b, an eccentric shaft portion 10c, a first arm portion 10d, and a second arm portion 10e. The first journal portion 10a is rotatably supported by the internal combustion engine main body. The control eccentric shaft portion 10b is provided at a position where the lower end portion of the first control link 7 is rotatably connected and eccentric with respect to the first journal portion 10a by a predetermined amount. The eccentric shaft portion 10c is provided at a position where one end portion 12a of the second control link 12 is rotatably connected and eccentric with respect to the first journal portion 10a by a predetermined amount. One end of the first arm portion 10d is connected to the first journal portion 10a, and the other end is connected to the lower end portion of the first control link 7. One end of the second arm portion 10e is connected to the first journal portion 10a, and the other end is connected to one end portion 12a of the second control link 12.

One end of the arm link 13 is rotatably connected to the other end 12b of the second control link 12. A second control shaft 11 is connected to the other end of the arm link 13 so as not to be relatively movable. The arm link 13 is a member separate from the second control shaft 11.

The second control shaft 11 is rotatably supported in the housing 20, which will be described later, via a plurality of journal portions.

The second control link 12 connects the first control shaft 10 and the second control shaft 11. The second control link 12 has a lever shape, one end portion 12a connected to the eccentric shaft portion 10c has a substantially linear shape, and the other end portion 12b connected to the arm link 13 has a curved shape. The tip of the one end 12a is provided with an insertion hole through which the eccentric shaft portion 10c is rotatably inserted.

The second control shaft 11 rotates by the torque transmitted from the electric motor via the strain wave gearing reducer included in the actuator of the link mechanism for the internal combustion engine. When the second control shaft 11 rotates, the arm link 13 rotates about the second control shaft 11, the first control shaft 10 rotates via the second control link 12, and the lower end of the first control link 7 The position is changed. As a result, the posture of the lower link 5 changes, the stroke position and stroke amount of the piston 1 in the cylinder change, and the engine compression ratio changes accordingly.

Next, the configuration of the actuator of the link mechanism for the internal combustion engine according to the first embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a cross-sectional view of the actuator 100 of the link mechanism for an internal combustion engine according to the first embodiment of the present invention. The actuator 100 of the link mechanism for an internal combustion engine includes an electric motor 22, a strain wave gearing reducer 21, a housing 20, and a second control shaft 11.

The electric motor 22 is, for example, a brushless motor and includes a motor casing 45, a coil 46, a rotor 47, and a motor output shaft 48. The motor casing 45 is a bottomed cylindrical member. The coil 46 is fixed to the inner peripheral surface of the motor casing 45. The rotor 47 is rotatably provided inside the coil 46. The motor output shaft 48 is fixed to the center of the rotor 47, and one end thereof is rotatably supported by a ball bearing 52 provided at the bottom of the motor casing 45.

The strain wave gearing speed reducer 21 reduces the rotational speed of the motor output shaft 48 and transmits the torque of the motor output shaft 48 to the second control shaft 11.

The second control shaft 11 is rotatably supported by the housing 20, and has a control shaft 23 and a fixing flange 24. The control shaft 23 extends in the axial direction of the actuator 100. The fixing flange 24 is located at one end of the control shaft 23 and extends radially outward of the control shaft 23. The control shaft 23 and the fixing flange 24 are integrated to form a second control shaft 11 made of an iron-based metal material. The fixing flange 24 includes a plurality of bolt insertion holes formed at equal intervals in the circumferential direction of the outer peripheral portion. The fixing flange 24 of the second control shaft 11 is coupled to the flange portion 36b of the flexible external gear 36 of the strain wave gearing reducer 21 by the bolt inserted through the bolt insertion hole.

FIG. 3 is an exploded isometric view of the strain wave gearing reducer 21 according to the first embodiment of the present invention.

Next, the configuration of the strain wave gearing speed reducer 21 according to the first embodiment of the present invention will be described with reference to FIGS. 2 and 3.

The strain wave gearing speed reducer 21 is attached to one end of the electric motor 22 and is provided inside the housing 20. The strain wave gearing speed reducer 21 is fixed to the inside of the opening groove portion 20a of the housing 20 with bolts. Inside the opening groove 20a, a supply hole 20b for supplying lubricating oil from a hydraulic source (not shown in FIG. 2) opens above the wave gear speed reducer 21 in the direction of gravity. When the lubricating oil is supplied to the supply hole 20b, it drops onto the lower wave gear reducer 21 and lubricates between the rotating elements of the wave gear reducer 21.

The wave gear reducer 21 includes a rigid internal gear 27, a flexible external gear 36 arranged inside the rigid internal gear 27, a wave generator 37 arranged inside the flexible external gear 36, and a wave generator. It includes an input shaft connected to the central portion of 37. This input shaft is the motor output shaft 48 of the electric motor 22. Further, an output shaft is connected to the flexible external gear 36. This output shaft is the second control shaft 11 of the actuator 100.

The rigid internal gear 27 is a rigid annular member, and has a plurality of teeth 27a on the inner peripheral surface. The rigid internal gear 27 is fixed to the housing 20.

The flexible external gear 36 is arranged inside the rigid internal gear 27 in the radial direction, and has a plurality of teeth 36a on the outer peripheral surface. The teeth 36a can mesh with the teeth 27a of the rigid internal gear 27. The flexible external gear 36 is a thin-walled cylindrical member formed of a metal material and having a bottom surface portion, and is capable of bending and deforming. The number of teeth 36a of the flexible external gear 36 is two less than the number of teeth 27a of the rigid internal gear 27. The bottom surface portion of the flexible external gear 36 is a flange portion 36b. The flange portion 36b is provided with an insertion hole 36c through which the second control shaft 11 penetrates inside in the radial direction.

The flexible external gear 36 is connected to the second control shaft 11 of the actuator 100. The second control shaft 11 penetrates the insertion hole 36c of the flexible external gear 36. The flange portion 36b of the flexible external gear 36 is bolted to the fixing flange 24 of the second control shaft 11. Therefore, the flexible external gear 36 can support the second control shaft 11 with the insertion hole 36c, and can secure the rigidity of the bottom portion.

The wave generator 37 is an annular member having an elliptical outer circumference, is arranged inside the flexible outer gear 36 in the radial direction, and the outer peripheral surface slides along the inner peripheral surface of the flexible outer gear 36. It is possible. The wave generator 37 includes a wave generation plug 371 and a deep groove ball bearing 372, and an input shaft (motor output shaft 48) is connected to the central portion. The wave generation plug 371 has an elliptical outer circumference, and a motor output shaft 48 is fixed to the central portion thereof by press fitting. The deep groove ball bearing 372 includes a flexible thin inner and outer ring located between the outer circumference of the wave generation plug 371 and the inner circumference of the flexible outer gear 36, and the thin inner and outer rings are flexible with the wave generation plug 371. Allows relative rotation between the external gears 36.

When the motor output shaft 48 of the electric motor 22 rotates, the wave generation plug 371 rotates. The rotation of the wave generation plug 371 causes the flexible external gear 36 to rotate, and the second control shaft 11 of the actuator 100 to rotate. In this way, the torque of the motor output shaft 48 is transmitted to the second control shaft 11 via the strain wave gearing reducer 21. When the second control shaft 11 is rotated by the torque transmitted from the electric motor 22 via the strain wave gearing speed reducer 21, the arm link 13 rotates about the second control shaft 11 (see FIG. 1).

Next, the torque limiter mechanism provided in the strain wave gearing speed reducer 21 according to the first embodiment of the present invention will be described with reference to FIGS. 4 and 5. The torque limiter mechanism is flexible from the wave generator 37 in order to prevent the wave gear reducer 21 from being damaged by the excessive torque when an excessive torque is generated on the motor output shaft 48 of the electric motor 22. Limits the torque transmitted to the external gear 36.

FIG. 4 is an axial cross-sectional view of the wave generator 37 and the motor output shaft 48 of the strain wave gearing speed reducer 21 according to the first embodiment of the present invention. FIG. 5 is a radial cross-sectional view of the wave generator 37 and the motor output shaft 48 at the connection position between the wave generator 37 and the motor output shaft 48. The axial direction is the axial direction of the actuator 100, that is, the axial direction of the motor output shaft 48 and the second control shaft 11, and the radial direction is a direction perpendicular to the axial direction. As described above, the wave generation plug 371 of the wave generator 37 has an elliptical outer circumference, and the motor output shaft 48 is fixed to the central portion thereof.

The motor output shaft 48 includes a plurality of torque limiter mechanisms 60 in the circumferential direction. The torque limiter mechanism 60 includes an elastic member 60a such as a spring and a spherical member 60b such as a steel ball, and is arranged at equal intervals in the circumferential direction of the motor output shaft 48. The motor output shaft 48 is provided with a groove 48a on the connection surface with the wave generation plug 371. The groove portion 48a extends in the radial direction, the outer side in the radial direction opens (that is, the groove portion 48a opens at the connection surface with the wave generation plug 371 of the motor output shaft 48), and the elastic member 60a is installed in the groove portion 48a. In the elastic member 60a, the spherical member 60b is fixed to one end on the radial outer side (that is, the opening side of the groove portion 48a), the other end abuts on the bottom portion of the groove portion 48a, and the elastic force acts mainly in the radial direction.

Although the motor output shaft 48 has a shape in which the diameter of the connecting portion with the wave generation plug 371 is larger than the diameter of the other portion in FIG. 4, it does not have to have such a shape, for example, the diameter is large. It may have a shape with a constant diameter.

The wave generation plug 371 is provided with a concave portion 371a recessed outward in the radial direction on the inner peripheral surface (that is, the connection surface with the motor output shaft 48). Under normal conditions when excessive torque is not applied to the strain wave gearing speed reducer 21, the groove 48a and the recess 371a are in the same circumferential position, and the opening of the groove 48a and the opening of the recess 371a face each other. is doing.

In a normal state where an excessive torque is not applied to the strain wave gearing speed reducer 21, a part of the spherical member 60b protrudes from the opening portion of the groove portion 48a due to the elastic force of the elastic member 60a, and a part of the spherical member 60b protrudes from the opening portion of the groove portion 48a. It's getting in. Therefore, the wave generation plug 371 rotates together with the motor output shaft 48, and the torque of the motor output shaft 48 is transmitted to the wave generation plug 371.

When the torque of the motor output shaft 48 exceeds a predetermined torque and an excessive torque acts on the strain wave gearing speed reducer 21, the force acting to cause the spherical member 60b to come out of the recess 371a due to this excessive torque is generated by the spherical member 60b. A part of the spherical member 60b becomes larger than the elastic force of the elastic member 60a that acts to stay in the recess 371a, and the spherical member 60b escapes from the recess 371a. When the spherical member 60b comes out of the recess 371a, slippage occurs between the motor output shaft 48 and the wave generation plug 371, and the torque transmitted from the motor output shaft 48 to the wave generation plug 371 is limited (spherical member 60b). And the friction between the wave generation plug 371 and the wave generation plug 371 transmits a torque smaller than usual). Therefore, it is possible to prevent the wave gear reducer 21 from being damaged due to the generation of excessive torque.

The characteristics and structure of the torque limiter mechanism 60, the groove 48a, and the recess 371a, such as the elastic force of the elastic member 60a, the size of the spherical member 60b, the depth of the groove 48a and the recess 371a, and the shape of the recess 371a, are described above. When a predetermined torque is generated, the spherical member 60b can be determined to come out of the recess 371a. This predetermined torque is a torque having a magnitude such that the strain wave gearing reducer 21 is not damaged, and can be predetermined by the configuration of the strain wave gearing reducer 21.

When the torque limiter mechanism 60 operates and the spherical member 60b comes out of the recess 371a, the motor output shaft 48 is in a so-called idle state, the torque transmitted to the strain wave gearing reducer 21 is limited, and the actuator 100 is controlled. It becomes impossible. The actuator 100 can be controlled when the spherical member 60b enters the recess 371a again. In the actuator 100 of the link mechanism for the internal combustion engine, an excessive torque that the torque limiter mechanism 60 acts on is generated in the wave gear reducer 21 for a moment. Therefore, the actuator 100 is immediately controlled while the excessive torque is eliminated. It is desirable to be able to do it. That is, it is desirable that the time during which the actuator 100 becomes uncontrollable is as short as possible.

In the strain wave gearing speed reducer 21 according to the present embodiment, a plurality of torque limiter mechanisms 60 are provided at equal intervals in the circumferential direction of the motor output shaft 48. Therefore, after the spherical member 60b has come out of the recess 371a, when the torque of the motor output shaft 48 becomes smaller than the above-mentioned predetermined torque and the excessive torque is eliminated, the spherical member 60b becomes the recess 371a by the rotation of the motor output shaft 48. It enters again, and the torque of the motor output shaft 48 is transmitted to the wave generation plug 371, and the actuator 100 can be controlled. In the strain wave gearing reducer 21 according to the present embodiment, the time during which the actuator 100 cannot be controlled is shortened in this way.

The number of torque limiter mechanisms 60 is preferably plural, and the larger the number, the more desirable. When the number of torque limiter mechanisms 60 is large, the distance between the recesses 371a in the circumferential direction becomes short, and the time until the spherical member 60b that has come out of the recesses 371a enters the recesses 371a again after the excessive torque is eliminated (that is, the actuator). The time when 100 becomes uncontrollable) can be shortened. Therefore, as the number of torque limiter mechanisms 60 increases, the actuator 100 can be controlled immediately after the excessive torque is eliminated.

The strain wave gearing reducer 21 according to the present embodiment has high reliability because it can prevent damage due to the generation of excessive torque and can shorten the time during which the actuator 100 becomes uncontrollable after the excessive torque is eliminated.

The strain wave gearing speed reducer 21 according to the second embodiment of the present invention will be described with reference to FIGS. 6 and 7. The strain wave gearing reducer 21 according to the present embodiment has the same configuration as the strain wave gearing gear reducer 21 according to the first embodiment, but the configuration of the torque limiter mechanism 60 is different. Hereinafter, the configuration of the torque limiter mechanism 60 in this embodiment will be described. The description of the configuration common to the strain wave gearing reducer 21 according to the first embodiment will be omitted.

FIG. 6 is an axial cross-sectional view of the wave generator 37 and the motor output shaft 48 of the strain wave gearing speed reducer 21 according to the second embodiment of the present invention. FIG. 7 is a radial cross-sectional view of the wave generator 37 and the motor output shaft 48 at the connection position between the wave generator 37 and the motor output shaft 48.

The wave generation plug 371 includes a plurality of torque limiter mechanisms 60 in the circumferential direction. The torque limiter mechanism 60 includes an elastic member 60a such as a spring and a spherical member 60b such as a steel ball, and is arranged at equal intervals in the circumferential direction of the wave generation plug 371. The wave generation plug 371 is provided with a groove portion 371b on the connection surface with the motor output shaft 48. The groove portion 371b is elongated in the radial direction, and the inside in the radial direction is opened (that is, the groove portion 371b is opened at the connection surface with the motor output shaft 48 of the wave generation plug 371), and the elastic member 60a is installed in the groove portion 371b. In the elastic member 60a, the spherical member 60b is fixed to one end on the inner side in the radial direction (that is, the opening side of the groove portion 371b), the other end abuts on the bottom portion of the groove portion 371b, and the elastic force acts mainly in the radial direction.

The motor output shaft 48 is provided with a concave portion 48b recessed inward in the radial direction on the outer peripheral surface (that is, the connection surface with the wave generation plug 371). In a normal state where an excessive torque is not applied to the strain wave gearing speed reducer 21, the groove portion 371b and the recess 48b are in the same position in the circumferential direction, and the opening portion of the groove portion 371b and the opening portion of the recess 48b face each other. is doing.

The groove portion 371b may have a structure in which the bottom portion (the end portion on the outer side in the radial direction) is open, and a plug screw 60c is provided at the bottom portion of the groove portion 371b so as to close the opening portion. In this configuration, the other end of the elastic member 60a comes into contact with the plug screw 60c provided at the bottom of the groove 371b. In this configuration, when the torque limiter mechanism 60 is installed in the wave generation plug 371, the torque limiter mechanism 60 is first inserted into the groove portion 371b from the outer peripheral portion of the wave generation plug 371, and then the plug screw 60c is inserted into the wave generation plug. The torque limiter mechanism 60 can be fixed by screwing into the groove portion 371b from the outer peripheral portion of the 371 with the plug screw 60c. When the elastic force of the elastic member 60a is large, it is easier to install the torque limiter mechanism 60 on the wave generation plug 371 with such a structure.

The operation of the torque limiter mechanism 60 in the normal state where the excessive torque is not applied to the strain wave gearing reducer 21 and when the excessive torque is applied to the strain wave gearing reducer 21 is almost the same as that described in the first embodiment. The same is true. That is, in a normal state, a part of the spherical member 60b is inserted in the recess 48b. When an excessive torque is applied to the strain wave gearing speed reducer 21, the spherical member 60b escapes from the recess 48b, causing slippage between the motor output shaft 48 and the wave generation plug 371, and the motor output shaft. The torque transmitted from 48 to the wave generation plug 371 is limited (a torque smaller than normal is transmitted due to friction between the spherical member 60b and the motor output shaft 48), and the strain wave gearing reducer 21 due to the generation of excessive torque. Can be prevented from being damaged.

Further, when the torque of the motor output shaft 48 becomes smaller than the predetermined torque after the spherical member 60b has come out of the recess 48b, the spherical member 60b reenters the recess 48b due to the rotation of the motor output shaft 48, and the torque of the motor output shaft 48 Is transmitted to the wave generation plug 371, and the actuator 100 can be controlled.

Similar to the strain wave gearing gear reducer 21 according to the first embodiment, the strain wave gearing reducer 21 according to the present embodiment can prevent damage due to the generation of excessive torque, and the time during which the actuator 100 becomes uncontrollable after the excessive torque is eliminated. It has high reliability because it can be shortened.

The strain wave gearing speed reducer 21 according to the third embodiment of the present invention will be described with reference to FIGS. 8, 9 and 10. Hereinafter, the configuration of the strain wave gearing reducer 21 according to the present embodiment will be described based on the configuration of the strain wave gearing reducer 21 according to the first embodiment. The configuration of the strain wave gearing reducer 21 according to the present embodiment can also be obtained based on the configuration of the strain wave gearing reducer 21 according to the second embodiment.

The actuator 100 of the link mechanism for the internal combustion engine is always operating during the operation of the internal combustion engine, and an excessive torque such that the torque limiter mechanism 60 acts is generated in the strain wave gearing speed reducer 21 for a moment. For example, such an excessive torque is generated by an impact force momentarily applied to the piston 1. In order to continuously operate the actuator 100, it is required to return the torque limiter mechanism 60 to the state before the operation as soon as possible when the excessive torque is resolved so that the actuator 100 can be controlled immediately.

In the wave gear reducer 21 according to the first and second embodiments, since a plurality of torque limiter mechanisms 60 are provided at equal intervals in the circumferential direction of the motor output shaft 48 or the wave generation plug 371, the actuator 100 cannot be controlled. You can save time. In the strain wave gearing reducer 21 according to the present embodiment, when the excessive torque is eliminated, the torque limiter mechanism 60 is returned to the state before the action more quickly, and the time during which the actuator 100 becomes uncontrollable is further shortened. Be prepared.

FIG. 8 is a radial cross-sectional view of the wave generator 37 and the motor output shaft 48 at the connection position between the wave generator 37 and the motor output shaft 48 of the strain wave gearing speed reducer 21 according to the third embodiment of the present invention.

The wave generation plug 371 is provided with a groove portion 62 extending in the circumferential direction on the inner peripheral surface (that is, the connecting surface with the motor output shaft 48). The groove portion 62 opens in the radial direction (that is, opens at the connection surface of the wave generation plug 371 with the motor output shaft 48).

The motor output shaft 48 includes a groove portion 63 extending in the circumferential direction on the outer peripheral surface (that is, the connection surface with the wave generation plug 371). The groove 63 opens on the outer side in the radial direction (that is, opens at the connection surface of the motor output shaft 48 with the wave generation plug 371).

In the normal state where an excessive torque is not applied to the strain wave gearing speed reducer 21, that is, when a part of the spherical member 60b is inserted into the recess 371a, the groove portion 62 and the groove portion 63 are in the same circumferential position. The opening portion of the groove portion 62 and the opening portion of the groove portion 63 face each other. Since the opening portion of the groove portion 62 and the opening portion of the groove portion 63 face each other, a space 64 is formed at the connection portion between the wave generation plug 371 and the motor output shaft 48. Therefore, the wave gear reducer 21 normally includes a space 64 at a connection portion (sliding contact portion) between the wave generation plug 371 and the motor output shaft 48.

The space 64 is formed by the groove portion 62 and the groove portion 63, and extends in the circumferential direction in the same manner as the groove portions 62 and 63. An elastic member 61 such as a spring is installed in the space 64 so that an elastic force acts mainly in the circumferential direction.

FIG. 9 is a diagram showing an elastic member 61 installed in the space 64 in a normal time when an excessive torque is not applied to the strain wave gearing reducer 21. The space 64 is provided with one end 62a of the groove portion 62 at one end in the circumferential direction and one end 63a of the groove portion 63 at the other end in the circumferential direction (one end 63a of the groove portion 63 is opposite to one end 62a of the groove portion 62 in the circumferential direction. Located on the side). One end of the elastic member 61 abuts on one end 62a of the groove 62, and the other end abuts on one end 63a of the groove 63.

When the torque of the motor output shaft 48 exceeds a predetermined torque and an excessive torque acts on the strain wave gearing speed reducer 21, the spherical member 60b escapes from the recess 371a and the torque limiter mechanism 60 operates to operate the motor output. The shaft 48 slides from the wave generation plug 371 and rotates in the circumferential direction with respect to the wave generation plug 371.

FIG. 10 is a diagram showing an elastic member 61 installed in the space 64 when an excessive torque is applied to the strain wave gearing reducer 21. When the motor output shaft 48 rotates in the circumferential direction (clockwise in FIG. 10) with respect to the wave generation plug 371, the positions of the groove 62 and the groove 63 in the circumferential direction become different from each other, and the groove 62 One end 62a and one end 63a of the groove 63 come close to each other. That is, the space 64 has a shorter length in the circumferential direction.

The elastic member 61 contracts when the length of the space 64 in the circumferential direction becomes short, and when the excessive torque is eliminated, at least one of the wave generation plug 371 and the motor output shaft 48 is rotated by the elastic force, and the groove portion 62 and the groove portion 63 are formed. Make the positions in the circumferential direction the same as each other. That is, when the excessive torque is eliminated, the excessive torque acts on the wave gear speed reducer 21 due to the elastic force of the elastic member 61 at the relative positions of the wave generation plug 371 and the motor output shaft 48 in the circumferential direction. It automatically (forces) returns to its normal position (Fig. 9). Then, the spherical member 60b reenters the recess 371a, the torque of the motor output shaft 48 is transmitted to the wave generation plug 371, and the actuator 100 can be controlled.

The number of the groove portion 62, the groove portion 63, and the elastic member 61 is one or more. The characteristics and structure of the groove 62, the groove 63, and the elastic member 61, such as the number of the groove 62, the groove 63, and the elastic member 61, the elastic force of the elastic member 61, and the length of the groove 62 and the groove 63 in the circumferential direction, are the motor outputs. Even if the torque of the shaft 48 exceeds the predetermined torque described in the first embodiment, the one end 62a of the groove 62 and the one end 63a of the groove 63 are very close to each other so that the elastic member 61 does not shrink to the limit ( That is, it can be determined (so that the elastic member 61 does not cause a so-called bottom thrust).

Since the actuator 100 of the link mechanism for the internal combustion engine is always operating during the operation of the internal combustion engine, if the excessive torque generated in the wave gear reducer 21 is eliminated (especially if the excessive torque generated only for a moment is eliminated). , It is required to be controllable as soon as possible. The strain wave gearing reducer 21 according to the present embodiment includes an elastic member 61, and by utilizing the elastic force of the elastic member 61, the spherical member 60b that has come out of the recess 371a is relocated to the recess 371a after the excessive torque is eliminated. The time required for entry can be significantly shortened, and the actuator 100 can be controlled even faster after the excessive torque is eliminated. As described above, the strain wave gearing reducer 21 according to the present embodiment can significantly reduce the time during which the actuator 100 cannot be controlled, and has high reliability.

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

1 ... Piston, 2 ... Piston pin, 3 ... Upper link, 4 ... Crankshaft, 4a ... Crank pin, 5 ... Lower link, 6 ... Connecting pin, 7 ... First control link, 8 ... Connecting pin, 9 ... Link mechanism 10, 10 ... 1st control shaft, 10a ... 1st journal part, 10b ... Control eccentric shaft part, 10c ... Eccentric shaft part, 10d ... 1st arm part, 10e ... 2nd arm part, 11 ... 2nd control shaft, 12 ... 2nd control link, 12a ... One end of the 2nd control link, 12b ... The other end of the 2nd control link, 13 ... Arm link, 20 ... Housing, 20a ... Open groove, 20b ... Supply hole, 21 ... Wave gear Reducer, 22 ... electric motor, 23 ... control shaft, 24 ... fixing flange, 27 ... rigid internal gear, 27a ... teeth, 36 ... flexible external gear, 36a ... teeth, 36b ... flange part, 36c ... insertion hole , 37 ... wave generator, 45 ... motor casing, 46 ... coil, 47 ... rotor, 48 ... motor output shaft, 48a ... groove, 48b ... recess, 52 ... ball bearing, 60 ... torque limiter mechanism, 60a ... elastic member, 60b ... Spherical member, 60c ... Plug screw, 61 ... Elastic member, 62 ... Groove, 62a ... One end of groove, 63 ... Groove, 63a ... One end of groove, 64 ... Space, 100 ... Actuator of link mechanism for internal combustion engine, 371 ... Wave generation plug, 371a ... Recess, 371b ... Groove, 372 ... Deep groove ball bearing.

Claims (4)

Rigid internal gears that are annular and have multiple teeth on the inner peripheral surface,
A flexible external gear that is cylindrical, has a plurality of teeth on the outer peripheral surface, and is arranged inside the rigid internal gear.
A wave generator having an elliptical outer circumference, which is arranged inside the flexible external gear, and whose outer peripheral surface is slidable along the inner peripheral surface of the flexible external gear.
An input shaft connected to the central portion of the wave generator and rotating the wave generator to rotate the flexible external gear when rotated.
With multiple elastic members,
A plurality of spherical members, each of which is fixed to one end of the elastic member,
With
The wave generator and the input shaft are provided with a plurality of recesses opened in the circumferential direction at the connecting surface between the wave generator and the input shaft.
Each of the elastic members is installed in one of the recesses of the wave generator and the recess of the input shaft, and the spherical member is fixed to the one end on the opening side of the one recess.
Wherein each of the spherical member, which enters into the other recess of the recess with part of the concave portion of the wave generator said input shaft,
The wave generator is provided with at least one groove portion extending in the circumferential direction and opening at the connecting surface with the input shaft on the connecting surface with the input shaft.
The input shaft is provided with at least one groove portion extending in the circumferential direction and opening at the connecting surface with the wave generator on the connecting surface with the wave generator.
At the connection portion between the wave generator and the input shaft, the opening portion of the groove portion extending in the circumferential direction of the wave generator and the opening portion of the groove portion extending in the circumferential direction of the input shaft face each other. The space formed by that is provided,
The space includes one end of the groove extending in the circumferential direction of the wave generator at one end in the circumferential direction, and one end of the groove extending in the circumferential direction of the input shaft at the other end of the circumferential direction.
An elastic member is installed in the space.
The elastic member installed in the space has one end abutting on the one end of the groove extending in the circumferential direction of the wave generator, and the other end of the groove extending in the circumferential direction of the input shaft. Contact one end ,
The groove portion extending in the circumferential direction of the wave generator and the groove portion extending in the circumferential direction of the input shaft are
When a part of the spherical member enters the recess of the wave generator and the recess of the input shaft into the other recess, the positions in the circumferential direction are the same as each other.
When the torque of the input shaft increases and a part of the spherical member enters the other recess and exits from the other recess, the positions in the circumferential direction are different from each other.
A wave gear reducer characterized by that. The input shaft is provided with a groove portion extending in the radial direction and opening at the connection surface with the wave generator as the recess on the connection surface with the wave generator.
The wave generator is provided with the recess that opens at the connection surface with the input shaft on the connection surface with the input shaft.
Each of the plurality of the elastic member, the placed in said extending in a radial direction of the input shaft groove, the spherical member to said one end of the opening side of the groove extending in the radial direction of the input shaft is fixed ,
A part of each of the spherical members is inserted into the recess of the wave generator.
The strain wave gearing gear reducer according to claim 1. The wave generator is provided with a groove portion extending in the radial direction and opening at the connection surface with the input shaft as the recess on the connection surface with the input shaft.
The input shaft is provided with the recess that opens at the connection surface with the wave generator on the connection surface with the wave generator.
Each of the plurality of elastic members is installed in the groove portion extending in the radial direction of the wave generator, and the spherical member is provided at the one end on the opening side of the groove portion extending in the radial direction of the wave generator. Fixed,
A part of each of the spherical members is inserted into the recess of the input shaft.
The strain wave gearing gear reducer according to claim 1. The strain wave gearing gear reducer according to any one of claims 1 to 3.
An electric motor with a motor output shaft and
The control shaft provided in the link mechanism of the internal combustion engine and
With
The motor output shaft is the input shaft and
The control shaft is connected to the flexible external gear.
An actuator of a link mechanism for an internal combustion engine.

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