JP2012219973A - Control method of power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method of a power transmission device in which power consumption required for holding is reduced when holding an output shaft from forward rotation in the power transmission device in which rotation power is transmitted without being reduced in speed during forward rotation of an input shaft, and the rotation power is transmitted being reduced in speed during backward rotation of the input shaft.SOLUTION: When holding a rotation angle against an external force applied to an output shaft of a power transmission device while stopping the output shaft from forward rotation (S10:YES), a control device outputs a backward rotation command Sfr to a motor (S20) and temporarily switches an input shaft from forward rotation to backward rotation. After the lapse of "switching determination time Tc" within which switching from an idling state to a power transmitting state is completed in a two-way clutch (S30:YES), a stop command Srs from backward rotation is output to the motor (S40) and the input shaft is switched from backward rotation to stop. Thus, power consumption required for holding can be reduced in comparison with the case of holding the output shaft while stopping it from forward rotation.

Description

  The present invention relates to a method for controlling a power transmission device that transmits a rotational force of an input shaft to an output shaft.

The power transmission device transmits the rotation of the input shaft by a driving force of a motor or the like at a constant speed or by decelerating or increasing the speed to the output shaft, and drives a target operation mechanism connected to the output shaft. In an ordinary power transmission device, the transmission ratio between the input shaft and the output shaft and the output characteristics of the transmission torque are constant regardless of the rotation direction of the input shaft. However, there are cases where different output characteristics are required depending on the forward and reverse rotations of the power or the operation of the forward path and the return path of the actuator as the target operation mechanism.
For example, in a variable compression ratio engine that can change the compression ratio of the engine, when changing from the low compression ratio side to the high compression ratio side, low speed and high torque are required, while on the other hand, the high compression ratio side is changed to the low compression ratio side. In this case, torque is not required and high speed characteristics are required.

  Conventionally, as a device for changing output characteristics in forward rotation and reverse rotation or in the forward and backward directions, a device using electronic control, or a device for selecting a power transmission path having a different gear ratio by mechanically or electrically detecting the rotation direction It has been known. However, such a device has a complicated structure, a large physique, and a high cost. Further, for example, since a circuit for controlling the solenoid in synchronism with the rotation direction of the motor, a sensor, or a control element is necessary, fine operation is difficult and operation may be uncertain.

  Therefore, for example, Patent Document 1 discloses an invention relating to a variable compression ratio engine as a device that automatically switches a power transmission path without requiring electronic control, detection of a rotational direction, or the like. The device of Patent Document 1 uses two one-way clutches that restrain rotations in opposite directions, and each one-way clutch transmits a rotational force to a transmission path having a different gear ratio, so that the gear ratio is changed according to the rotation direction. Trying to switch.

Japanese Patent No. 4333129

  However, according to the verification by the present applicant, in the device of Patent Document 1, the two one-way clutches are in the power transmission state at the same time, deadlock, that is, "the transmission systems cause mutual interference due to power transmission with different gear ratios. “Power transmission is impossible”. After all, simply combining two one-way clutches cannot constitute a mechanism for switching the gear ratio between forward rotation and reverse rotation. Therefore, the present applicant has previously filed a joint application for an invention relating to a power transmission device that solves this problem (Japanese Patent Application No. 2011-0663012).

However, the power transmission apparatus according to the previous application has a new problem because of the characteristic that the gear ratio is switched between forward rotation and reverse rotation.
The problem occurs when an external force in the rotational direction is applied to the output shaft while the output shaft is stopped, for example, when the target operation mechanism constantly applies a load to the output shaft. In this case, since the drive means “holds” the output shaft from being rotated by an external force, it is necessary to generate a constant holding torque on the input shaft. The holding torque is determined by the rotation direction before stopping the output shaft. In other words, holding from forward rotation that transmits at a constant speed requires holding torque that is equal to the torque applied to the output shaft. On the other hand, in the holding from the reverse rotation that transmits the deceleration, the holding torque may be (1 / reduction ratio) with respect to the torque applied to the output shaft.
As described above, when the output shaft is held from the normal rotation, the holding torque is increased as compared with the case where the output shaft is held from the reverse rotation, thereby increasing the power consumption of the driving means.

  The present invention was created in view of the above points, and an object of the present invention is to provide a power transmission device that transmits a rotational force at a constant speed when the input shaft rotates in a normal direction and transmits the rotational force at a reduced speed when the input shaft rotates in a reverse direction. An object of the present invention is to provide a method for controlling a power transmission device that reduces power consumption required for holding when the output shaft is held from normal rotation.

The invention described in claims 1 to 4 is an invention relating to a control method for holding the output shaft of the following power transmission device.
This power transmission device transmits the rotational force of the input shaft driven by the driving means to the output shaft. Here, if the rotation of the input shaft in one rotation direction is “forward rotation” and the rotation of the input shaft in the other rotation direction is “reverse rotation”, the power transmission device Is rotated at the same speed as the input shaft. Further, when the input shaft is reversely rotated, the output shaft is decelerated and rotated with respect to the rotation of the input shaft.

The power transmission device includes an input transmission member, a first transmission member, a second transmission member, an output transmission member, a one-way rotational force transmission member, and a two-way rotational force transmission member.
The input transmission member is fixed to the input shaft and rotates together with the input shaft.
The first transmission member is fixed to an input side auxiliary shaft provided on a shaft different from the input shaft, and the rotation of the input transmission member is transmitted to rotate together with the input side auxiliary shaft.
The second transmission member is fixed to an output side auxiliary shaft provided on a shaft different from the output shaft, and rotates together with the output side auxiliary shaft.
The output transmission member is fixed to the output shaft, and the rotation of the second transmission member is transmitted to rotate together with the output shaft.
Specifically, gears, pulleys, and the like can be used as the transmission members.

The unidirectional rotational force transmitting member can transmit the normal rotation force of the input shaft to the output shaft when the input shaft rotates normally, and can cause the output shaft to idle when the input shaft rotates reversely.
The two-way rotational force transmission member can transmit the rotational force of the input side secondary shaft to the output side secondary shaft and cause the input side secondary shaft to idle with respect to the rotational force of the output side secondary shaft.
Specifically, a one-way clutch or the like can be used as the one-way rotational force transmission member. Further, specifically, a two-way clutch or the like can be used as the two-way rotational force transmission member.

  With the above configuration, in the power transmission device, during normal rotation of the input shaft, the normal rotation force of the input shaft is transmitted to the output shaft via the one-way rotational force transmission member. In addition, when the input shaft is reversely rotated, the reverse rotation force of the input shaft passes through the input transmission member, the first transmission member, the input side auxiliary shaft, the two-way rotational force transmission member, the output side auxiliary shaft, the second transmission member and the output transmission member And transmitted to the output shaft.

  As described as the problem of the prior art, a mechanism for switching the gear ratio between forward rotation and reverse rotation cannot be configured only by a combination of two one-way clutches, that is, one-way rotational force transmission members. On the other hand, this power transmission device uses a one-way rotational force transmission member and a two-way rotational force transmission member. "Mechanism for decelerating and transmitting force". Since this power transmission device has a simple configuration without using an external control device or a power selection device by other power, the physique can be reduced, the number of parts and the cost can be reduced, and the operation is reliable. Reliability can be improved.

  However, in this power transmission device, when the output shaft is held from the normal rotation, as described above, the holding torque increases as compared with the case where the output shaft is held from the reverse rotation, thereby increasing the power consumption of the driving means. There is.

Therefore, in order to solve this problem, the control method for the power transmission device according to claim 1 is configured such that when the rotation angle is maintained with respect to the external force applied to the output shaft while the output shaft is stopped from normal rotation, Including a first stage and a second stage.
In the first stage, the input shaft is switched from forward rotation to reverse rotation by the driving means.
In the second stage, following the first stage, the rotational force of the input side secondary shaft is output from the “idle state” in which the output side secondary shaft rotates idly with respect to the rotational force of the input side secondary shaft in the two-way rotational force transmission member. After switching to the “power transmission state” transmitted to the collateral shaft, the drive unit switches the input shaft from reverse rotation to stop.

  By reversing the input shaft, the power transmission device enters a deceleration power transmission state. If the reduction ratio between the input side and the output shaft at this time (= the rotational speed of the input shaft / the rotational speed of the output shaft) is the overall reduction ratio Zio, the two-way rotational force transmission member is in the “power transmission state”. Then, the torque of the input shaft becomes (1 / Zio) of the torque of the output shaft. That is, the holding torque required for the input shaft is equal to the torque applied to the output shaft from the outside when holding the output shaft from the normal rotation, whereas the output shaft is stopped from the reverse rotation and held. Sometimes it becomes (1 / Zio) of the torque applied to the output shaft from the outside. Therefore, by holding the output shaft from reverse rotation, the holding torque can be reduced to (1 / Zio) as compared to the case of holding the output shaft from normal rotation. Therefore, the power consumption of the driving means can be reduced.

According to the control method for the power transmission device according to the second aspect, the two-way rotational force transmission member is in the “idling state” when the rotational speed of the output side secondary shaft is larger than the rotational speed of the input side secondary shaft. Further, when the rotational speed of the output side secondary shaft is smaller than the rotational speed of the input side secondary shaft, the “power transmission state” is established.
Thus, it is determined whether the two-way rotational force transmission member is in the “idling state” or “power transmission state” based on the magnitude relationship between the rotational speed of the output side secondary shaft and the rotational speed of the input side secondary shaft. Can do.

According to the control method of the power transmission device according to the third aspect, the drive means switches the input shaft from the reverse rotation to the stop after the “predetermined delay time” has elapsed since the time when the input shaft was switched from the normal rotation to the reverse rotation.
The fact that the two-way rotational force transmission member has been switched from the “idle state” to the “power transmission state” can also be determined, for example, by detecting a change in the rotational direction of the output side auxiliary shaft. However, in that case, detection means and the like are required, and the configuration becomes complicated. Therefore, a “predetermined delay time” that is longer than the time required to switch from the “idle state” to the “power transmission state” is set in advance, and after the “predetermined delay time” has elapsed, the drive means switches the input shaft from reverse rotation to stop. If the switching is performed, the configuration becomes simple without the need for detection means or the like.

According to the control method for a power transmission device according to claim 4, the "predetermined delay time" is the rotation speed of the output side auxiliary shaft from the time when the input shaft is switched from normal rotation to reverse rotation at the maximum operating rotation speed of the input shaft. Is longer than the time until the rotational speed of the input side countershaft becomes equal.
After the drive means switches the input shaft from normal rotation to reverse rotation, the angle at which the output shaft rotates by inertia increases as the rotational speed of the input shaft increases. Therefore, the time from when the drive means switches the input shaft from normal rotation to reverse rotation until the rotational speed of the output side secondary shaft becomes equal to the rotational speed of the input side secondary shaft also increases as the rotational speed of the input shaft increases. become longer.

Therefore, the "predetermined delay time" is "from the time when the input shaft is switched from forward rotation to reverse rotation at the maximum operating rotational speed of the input shaft until the rotational speed of the output secondary shaft becomes equal to the rotational speed of the input secondary shaft. If the drive means is set to be longer than the `` time '', the two-way rotational force transmission member is always in the `` power transmission state '' when the drive means switches the input shaft from reverse rotation to stop, and the reverse rotation force of the input shaft is transmitted. ing.
Therefore, the output shaft can be reliably stopped from being reversed and held.

1 is an overall cross-sectional view of a power transmission device according to an embodiment of the present invention. It is an arrow view of the II direction of FIG. It is an arrow view of the III direction of FIG. 1 is a schematic diagram of a variable compression ratio engine to which a power transmission device of the present invention is applied. It is explanatory drawing explaining a one-way clutch. It is explanatory drawing explaining a two-way clutch. (A): It is a perspective view of a coupling and a spring. (B): It is a schematic cross section of the coupling when the input shaft is switched from stop to forward rotation. (C): A schematic cross-sectional view of the coupling when the input shaft is switched from forward rotation to stop or reverse rotation. It is a schematic diagram which shows the operation mechanism at the time of (a) normal rotation of the power transmission device by one Embodiment of this invention, and (b) reverse rotation. (A): It is a timing chart of the power transmission device of a comparative example. (B): It is a timing chart of the power transmission device by one Embodiment of this invention. It is a flowchart of the output shaft holding | maintenance process by one Embodiment of this invention. It is a timing chart at the time of the output shaft stop of the power transmission device by one Embodiment of this invention. In the power transmission device according to the embodiment of the present invention, (a) the relationship between the input shaft rotational speed n and the output shaft rotational angle α by inertia, and (b) the relationship between the input shaft rotational speed n and the reverse rotation switching time Tx by inertia. FIG.

Embodiments of the present invention will be described with reference to the drawings.
(One embodiment)
In one embodiment of the present invention, the power transmission device of the present invention is applied to a variable compression ratio engine mounted on an automobile or the like and capable of changing the compression ratio. A variable compression ratio engine 80 shown in FIG. 4 includes a cam cover 81, a cylinder head 82, a cylinder block 83, a lower case 84, and the like. A cylinder 85 is formed in the cylinder block 83, and a piston 86 is accommodated in the cylinder 85 so as to be reciprocally movable. The cylinder head 82 is provided with an intake valve 881 that opens and closes an intake passage and an exhaust valve 882 that opens and closes an exhaust passage. A space surrounded by the inner wall of the cylinder 85, the upper end of the piston 86, the intake valve 881 and the exhaust valve 882 forms a combustion chamber 89. A crankshaft 871, a connecting rod 872 and the like are accommodated in the lower case 84, and the reciprocating motion of the piston 86 is converted into the rotational motion of the crankshaft 871.
The cylinder block 83 is provided with a compression ratio changing mechanism including the power transmission device 10, the motor 17, the worm 18 and the worm wheel 19. The motor 17 corresponds to “driving means” recited in the claims.

Hereinafter, the rotation in the clockwise direction (hereinafter referred to as “CW direction”) when viewed from the input shaft side (left side in FIG. 4) of the power transmission device 10 is referred to as “forward rotation”, and the counterclockwise direction (hereinafter referred to as “CCW direction”). )) Is called “reverse”.
The control device 16 instructs the motor 17 to perform “forward rotation”, “reverse rotation”, and “stop”, and controls the rotation speed during forward rotation or reverse rotation. During normal rotation of the motor 17, the power transmission device 10 transmits the normal rotation force of the motor 17 to the worm 18 at a constant speed. Further, when the motor 17 is reversely rotated, the power transmission device 10 decelerates and transmits the reverse rotation force of the motor 17 to the worm 18.

In the state shown in FIG. 4, the cylinder block 83 is at the lowest position with respect to the lower case 84. At this time, the volume of the combustion chamber 89 is the minimum, and it is in a “high compression ratio” state in which the rate of volume change due to the movement of the piston 86 is maximized.
When the forward rotation force of the motor 17 is transmitted to the worm 18, the cam cover 81, the cylinder head 82, and the cylinder block 83 are raised with respect to the lower case 84, and the upper end position of the cam cover 81 is moved to the position indicated by the broken line in the figure. As a result, the volume of the combustion chamber 89 increases, so that the rate of volume change due to the movement of the piston 86 is reduced, resulting in a “low compression ratio” state. In the transition from the high compression ratio side to the low compression ratio side, the force applied to the cylinder block 83 by the combustion pressure in the combustion chamber 89 acts in the same direction, so that a large driving force is not required. Therefore, the power transmission device 10 can transmit the rotation of the motor 17 to the worm 18 at a constant speed, and can raise the cylinder block 83 at a relatively high speed.

  Subsequently, when the reverse rotation force of the motor 17 is transmitted to the worm 18, the cam cover 81, the cylinder head 82 and the cylinder block 83 are lowered with respect to the lower case 84. Thereby, since the volume of the combustion chamber 89 decreases, the volume change rate due to the movement of the piston 86 increases, and a state of “high compression ratio” is obtained. In the transition from the low compression ratio side to the high compression ratio side, it is necessary to lower the cylinder block 83 against the combustion pressure in the combustion chamber 89. Therefore, the power transmission device 10 can decelerate the rotation of the motor 17 and output a high torque.

Next, the structure of the power transmission device 10 is demonstrated based on FIGS. 1-3 and 5-7.
1 to 3, the power transmission device 10 includes a housing 60, an input side support plate 61, an output side support plate 62, an input shaft 11, an output shaft 12, an input side auxiliary shaft 51, an output side auxiliary shaft 52, and the like. Is provided. The input shaft 11 and the input side auxiliary shaft 51 are rotatably supported by bearings 63 and 64 fixed to the input side support plate 61, and the output shaft 12 and the output side auxiliary shaft 52 are attached to the output side support plate 62. It is rotatably supported by fixed bearings 65 and 66. Further, the output shaft 12 is rotatably supported by a bearing 67 fixed to the housing 60, and the input side auxiliary shaft 51 is rotatably supported by a bearing 68 fixed to the housing 60.

  The input shaft 11 and the output shaft 12 rotate about the rotation axis P. The input side auxiliary shaft 51 and the output side auxiliary shaft 52 rotate around a rotation axis Q substantially parallel to the rotation axis P. The input shaft 11 is connected to power such as a motor, and the output shaft 12 is connected to a target operation mechanism such as an actuator. Instead of the output shaft 12 or in addition to the output shaft 12, the output side auxiliary shaft 52 may be connected to the target operation mechanism.

  The input shaft 11 and the output shaft 12 are connected via a coupling 20 and a one-way clutch 30. The coupling 20 includes an input rotor 21, an intermediate rotor 23, and a spring 29, and generates a rotation time difference between the input shaft 11 and the intermediate shaft 13. The one-way clutch 30 includes an intermediate shaft 13 as an inner ring 32 formed integrally with the intermediate rotor 23, an outer ring 31 formed integrally with the output shaft 12, and the like. The one-way clutch 30 transmits the normal rotation force of the intermediate shaft 13 to the output shaft 12 when the input shaft 11 rotates forward, and causes the output shaft 12 to idle with respect to the intermediate shaft 13 when the input shaft 11 rotates reversely. Further, the input side countershaft 51 and the output side countershaft 52 are connected via a two-way clutch 50. Details of the coupling 20, the one-way clutch 30, and the two-way clutch 50 will be described later.

An input gear 41 is fixed to the input shaft 11, and a first gear 42 is fixed to the input side auxiliary shaft 51. A second gear 43 is fixed to the output side auxiliary shaft 52, and an output gear 44 is fixed to the output shaft 12. The gears 41 to 44 are spur gears, and the input gear 41 and the first gear 42 mesh with each other, and the second gear 43 and the output gear 44 mesh with each other.
The number of teeth of the first gear 42 is larger than the number of teeth of the input gear 41, and the pitch circle diameter of the first gear 42 is larger than the pitch circle diameter of the input gear 41. Accordingly, the rotation of the input shaft 11 is transmitted to the input-side auxiliary shaft 51 while being decelerated while being rotated in the opposite direction. The number of teeth of the output gear 44 is larger than the number of teeth of the second gear 43, and the pitch circle diameter of the output gear 44 is larger than the pitch circle diameter of the second gear 43. Therefore, the rotation of the output side auxiliary shaft 52 is transmitted to the output shaft 12 after being decelerated while the rotation direction is opposite.

Here, the reduction ratio is defined as follows.
Zii: input side reduction ratio (= (number of teeth of first gear 42 / number of teeth of input gear 41) = (number of rotations of input shaft 11 and intermediate shaft 13 / number of rotations of input side auxiliary shaft 51))
Zoo: Output side reduction ratio (= (number of teeth of output gear 44 / number of teeth of second gear 43) = (number of rotations of output side auxiliary shaft 52 / number of rotations of output shaft 12))
Zio (= Zii × Zoo): overall reduction ratio (= (number of rotations of input shaft 11 and intermediate shaft 13 / number of rotations of output shaft 12))
In the present invention, in any embodiment, it is essential that “Zio> 1”, that is, “decelerate as a whole”. In the present embodiment, “Zii> 1, Zoo> 1”, that is, “decelerate as a whole” by decelerating both the input side and the output side.

Next, a specific configuration of the one-way clutch will be described with reference to FIG.
The one-way clutch 30 includes an outer ring 31, an inner ring 32, a plurality of rollers 33, and a spring 34. The plurality of rollers 33 are arranged in an annular gap sandwiched between the outer ring 31 and the inner ring 32. A wedge portion 31 a corresponding to each roller 33 is formed on the inner wall of the outer ring 31. The wedge portion 31a is formed in such a shape that the roller 33 is engaged in one side in the circumferential direction (CW direction in the figure) and the roller 33 is free in the other circumferential direction (CCW direction in the figure). The spring 34 is provided between the roller 33 and the roller 33 and presses the roller 33 against the outer ring 31 side.
In the standby state shown in FIG. 5A, the outer ring 31 and the inner ring 32 are stopped, and the roller 33 is pressed against the wedge portion 31a.

  FIG. 5C shows a case where the inner ring 32 that is the drive shaft rotates in the CW direction with respect to the outer ring 31, and FIG. Indicates the case of rotation. In either case, as indicated by the solid line arrow in the figure, the roller 33 is engaged with the wedge portion 31a, and the rotational force of the drive shaft is transmitted to the counterpart shaft via the roller 33. Here, when the rotation number of the inner ring 32 is Rin, the rotation number of the outer ring 31 is Rout, the rotation in the CW direction is positive, and the rotation in the CCW direction is negative, the power transmission state is established when “Rin> Rout”. .

  Next, FIG. 5E shows a case where the inner ring 32 that is the drive shaft rotates in the CCW direction with respect to the outer ring 31, and FIG. The case where it rotates in the CW direction is shown. In either case, as indicated by broken line arrows and “x” marks in the figure, the roller 33 slides between the outer ring 31 and the inner ring 32, the rotational force of the drive shaft is not transmitted, and the counterpart shaft rotates idle. That is, when “Rin <Rout”, the idling state is established.

In short, including the case where one of the outer ring 31 and the inner ring 32 is stopped, the direction of “relative rotation between the outer ring 31 and the inner ring 32” determines whether the power transmission state or the idling state occurs.
Further, as shown in FIG. 5 (b), when the roller 33 is engaged with the wedge 31a from the state separated from the wedge 31a to shift from the idling state to the power transmission state, or conversely, from the power transmission state to the idling state. When shifting to, rotation of a predetermined switching angle λ1 is necessary. The switching angle λ1 corresponds to so-called backlash.

Next, a specific configuration of the two-way clutch 50 will be described with reference to FIG.
As shown in FIG. 6A, which is an enlarged view of the VIa portion of FIG. 1, the two-way clutch 50 includes an input side countershaft 51 as an outer ring, an output side countershaft 52 as an inner ring, a roller 53, a cage 54, a slide. It consists of a dynamic spring 55, a case 56, and the like.
The holder 54 holds the roller 53. The sliding spring 55 is stretched by the radially inner end 55 a being hooked on the cage 54 and the radially outer sliding portion 55 b being in contact with the inner wall of the case 56. The case 56 is fixed to the housing 60, holds the radially outer side of the input side countershaft 51, and supports the output side countershaft 52 via a bearing 57 so as to be rotatable.

  FIG. 6B shows a case where the input side auxiliary shaft (outer ring) 51 rotates as a drive shaft. At this time, since the retainer 54 tries to stay in place due to the sliding resistance between the case 56 and the sliding spring 55, the roller 53 rotates relative to the input side countershaft 51 in the opposite direction. To do. When the roller 53 moves in the opposite direction and engages with the wedge portion 51 a, the rotation of the input side auxiliary shaft 51 is transmitted to the output side auxiliary shaft 52 through the roller 53. Here, assuming that the rotation speed of the input-side countershaft 51 is Sin and the rotation speed of the output-side countershaft 52 is Sout, the input-side countershaft is satisfied when “Sin> Sout” regardless of the rotation direction of the input-side countershaft 51. The rotational force is transmitted from 51 to the output side countershaft 52.

FIG. 6C shows a case where the output side auxiliary shaft (inner ring) 52 rotates as a drive shaft. At this time, the retainer 54 and the input side countershaft 51 do not move. Since the roller 53 is located in the concave portion 51b on the radially inner side of the input side auxiliary shaft 51 and cannot mesh with the input side auxiliary shaft 51 and the output side auxiliary shaft 52, only the output side auxiliary shaft 52 rotates. Therefore, regardless of the rotation direction of the output side auxiliary shaft 52, when “Sin <Sout”, the rotational force is not transmitted from the output side auxiliary shaft 52 to the input side auxiliary shaft 51, and the input side auxiliary shaft 51 idles.
Similarly to the one-way clutch 30, when the two-way clutch 50 shifts from the idling state to the power transmission state, or when the two-way clutch 50 shifts from the power transmission state to the idling state, it is necessary to rotate at a predetermined switching angle λ2 corresponding to backlash. It is.

Next, the configuration of the coupling 20 will be described with reference to FIG.
As shown in FIG. 7A, the coupling 20 includes a columnar input rotor 21, an intermediate rotor 23, and a coiled spring 29. The input rotor 21 is provided coaxially and integrally with the input shaft 11. The intermediate rotor 23 is provided coaxially and integrally with the intermediate shaft 13.
As shown in FIG. 7B, the input rotor 21 is provided with two fan-shaped projecting portions 22 projecting on the end surface on the intermediate rotor 23 side. On the other hand, the intermediate rotor 23 is provided with two fan-shaped stopper portions 24 on the end face on the input rotor 21 side. The protruding portion 22 and the stopper portion 24 are each disposed on the target with respect to the rotation axis P. The protrusion 22 is disposed between the stopper portions 24 in the circumferential direction so as to be relatively rotatable with respect to the stopper portion 24 within a predetermined play angle θ.

  In other words, the protrusion 22 can be relatively rotated by a play angle θ from an “initial position” that contacts the outer wall 25 on the CW side of the stopper 24 to a “limit position” that contacts the outer wall 26 on the CCW side of the stopper 24. is there. When the projection 22 reaches the limit position during normal rotation of the input rotor 21, the projection 22 abuts against the outer wall 26 of the stopper 24 and integrally rotates forward. Thereby, power transmission from the input rotor 21 to the intermediate rotor 23 becomes possible.

  As shown in FIG. 7A, both ends of the spring 29 are locked to claw portions 27 and 28 provided on the outer circumferences of the input rotor 21 and the intermediate rotor 23. The spring 29 is pulled to generate a load when the input rotor 21 rotates forward with respect to the intermediate rotor 23 from the initial position. Therefore, as shown in FIG. 7C, when the input rotor 21 is switched from normal rotation to stop or reverse rotation, the spring 29 is in the initial position where the protrusion 22 secures the play angle θ with respect to the stopper portion 24. The input rotor 21 is urged in the CCW direction with respect to the intermediate rotor 23 so as to return.

  In the configuration of the embodiment described above, the input gear 41, the first gear 42, the second gear 43, and the output gear 44 are respectively “input transmission member” and “first transmission member” described in the claims. , “Second transmission member” and “output transmission member”. The one-way clutch 30 corresponds to a “one-way rotational force transmission member”.

Next, the operation of the power transmission device 10 will be described with reference to FIGS. The thick line arrow indicates the transmitted driving force Fd, and the middle thick line broken line arrow indicates the non-driving force Fn. A thin line arrow indicates rotation in the CW direction or CCW direction.
As shown in FIG. 8A, when the input shaft 11 rotates forward, the normal rotation force is transmitted to the intermediate shaft 13 via the coupling 20. Then, since the rotational speed Rin of the inner ring 32 is a positive value in the one-way clutch 30, if the rotational speed Rout of the outer ring 31 is regarded as zero, the relationship of “Rin> Rout” is established, and the forward rotation force is applied to the output shaft. 12 is transmitted at a constant speed (see FIG. 5C).

  At this time, due to the meshing of the input gear 41 and the first gear 42, the input side countershaft 51 is decelerated and reversely rotated. On the other hand, the output side countershaft 52 is increased in speed by the meshing of the output gear 44 and the second gear 43 and reversely rotated. Then, in the two-way clutch 50, the rotational speed Sout of the inner ring (output-side secondary shaft) 52 is larger than the rotational speed Sin of the outer ring (input-side secondary shaft) 51 (Sin <Sout). It idles with respect to the axis | shaft 51 (refer FIG.6 (c)).

  On the other hand, as shown in FIG. 8B, when the input shaft 11 rotates in the reverse direction, the input side countershaft 51 is decelerated and rotates forward due to the meshing of the input gear 41 and the first gear 42. Then, in the two-way clutch 50, the rotational speed Sin of the outer ring (input-side secondary shaft) 51 is larger than the rotational speed Sout of the inner ring (output-side secondary shaft) 52 that is stopped (Sin> Sout). The forward rotation force 51 is transmitted to the output side auxiliary shaft 52 (see FIG. 6B). The output shaft 12 is decelerated and reversely rotated by the meshing of the second gear 43 and the output gear 44. As a result, the reverse rotation force of the input shaft 11 is decelerated and transmitted to the output shaft 12.

  At this time, the reverse rotation force of the input shaft 11 is transmitted to the intermediate shaft 13 via the coupling 20. However, since the rotational speed Rin of the inner ring 32 in the one-way clutch 30 is a negative value, if the rotational speed Rout of the outer ring 31 is regarded as zero, the relationship “Rin <Rout” is established, and the output shaft 12 rotates idly. (See FIG. 5 (e)).

Next, the behavior when the input shaft 11 switches from reverse rotation to normal rotation will be described with reference to FIG. First, as a comparative example for one embodiment of the present invention, FIG. 9A shows a timing chart when the power transmission device does not include a coupling.
Here, each variable is defined as follows. The input side reduction ratio Zii is as described above.
n (1 / s): Number of rotations per second of the input shaft 11 (forward rotation is positive and reverse rotation is negative)
λ1 (deg): switching angle of the one-way clutch 30 λ2 (deg): switching angle of the two-way clutch 50 T1 (s): time for which the intermediate shaft 13 (= the inner ring 32 of the one-way clutch 30) rotates by the switching angle λ1 T2 (s) : Time required for the input shaft 11 and the intermediate shaft 13 to rotate at an angle Zii × λ2 corresponding to the input side auxiliary shaft 51 (= the outer ring of the two-way clutch 50) rotating at the switching angle λ2

Times T1 and T2 are expressed by the following formulas 1 and 2.
T1 = λ1 / (360 · n) (Formula 1)
T2 = Zii × λ2 / (360 · n) (Expression 2)
Therefore, when Zii × λ2> λ1, T2> T1 as shown in FIG. Then, if the time at which the input shaft 11 switches from reverse rotation to normal rotation is t0, the one-way clutch 30 shifts from the idling state to the power transmission state after time T1 from time t0, and the two-way clutch 50 is after time T2 from time t0. Transition from the power transmission state to the idling state. Therefore, the one-way clutch 30 and the two-way clutch 50 are simultaneously in a power transmission state within a range indicated by hatching in the figure, and so-called deadlock occurs.
When the input shaft 11 switches from forward rotation to reverse rotation, the one-way clutch 30 shifts from the power transmission state to the idle rotation state, and then the two-way clutch 50 shifts from the idle rotation state to the power transmission state, so that no deadlock occurs.

In order to solve this problem, an embodiment of the present invention includes a coupling 20 having a play angle θ. Here, the play angle θ is set to satisfy the following expression 3.
θ ≧ Zii × λ2−λ1 (Formula 3)
When Zii × λ2> λ1, θ takes a positive value. Further, the time Tθ is defined as follows.
Tθ (s): time for the input shaft 11 to rotate with respect to the intermediate shaft 13 by a play angle θ

In other words, Tθ is the “following delay time” of the intermediate shaft 13 when the input shaft 11 is switched from reverse rotation to normal rotation. As a result, as shown in the timing chart of FIG. 9B, the one-way clutch 30 shifts from the idling state to the power transmission state after time (T1 + Tθ) from time t0. Therefore, the one-way clutch 30 and the two-way clutch 50 are not in the power transmission state at the same time, and the occurrence of deadlock can be avoided.
When the input shaft 11 is switched from forward rotation to reverse rotation, the projection 22 is returned to the initial position by the spring 29 of the coupling 20, so that the rotation between the input shaft 11 and the intermediate shaft 13 is caused by the play angle θ. There is no time difference. Therefore, it behaves the same as the comparative example shown in FIG.

  As described above, the power transmission device 10 according to the embodiment of the present invention uses the one-way clutch 30 and the two-way clutch 50, and thus “input shaft A mechanism that transmits the rotational force at a constant speed during forward rotation and transmits the rotational force at a reduced speed when the input shaft rotates in reverse can be realized.

By the way, it can be considered that an external force in the rotational direction is applied to the output shaft 12 from the target operation mechanism (the worm 18 in the present embodiment) connected to the output shaft 12 when the output shaft 12 is stopped. In this case, since the motor 17 “holds” the output shaft 12 so as not to rotate due to an external force, it is necessary to generate a constant holding torque on the input shaft 11. The holding torque is determined by the rotation direction before the output shaft 12 is stopped. That is, in holding from forward rotation that transmits at a constant speed, a holding torque equal to the torque applied to the output shaft 12 is required. On the other hand, in the holding from the reverse rotation that transmits the deceleration, the holding torque becomes (1 / Zio) with respect to the torque applied to the output shaft 12.
As described above, when the output shaft 12 is held from the forward rotation, the holding torque is increased as compared with the case where the output shaft 12 is held from the reverse rotation, so that the power consumption of the motor 17 is increased. Therefore, even when the output shaft 12 is held from normal rotation, it becomes a problem to reduce the power consumption of the motor 17.

The operation when holding the output shaft 12 in a stopped state will be described with reference to FIGS.
First, FIG. 11A shows a timing chart in the case where the output shaft 12 is stopped and held as it is from normal rotation. When the input shaft 11 and the output shaft 12 are rotating forward, the one-way clutch 30 is in a power transmission state, and the forward rotation force of the input shaft 11 is transmitted to the output shaft 12 at a constant speed. On the other hand, the two-way clutch 50 is idling.
From this state, the control device 16 outputs a stop command Sfs from normal rotation to the motor 17 at time tfs. If the shaft rotation angle at this time is 0, the input shaft 11 directly connected to the shaft of the motor 17 is abruptly braked and stops at the forward rotation stop angle β1. In other words, the input shaft 11 shifts from the “forward rotation” mode to the “stop” mode at the forward rotation stop angle β1.

In the one-way clutch 30, the intermediate shaft 13 that is the inner ring 32 stops with a delay of the play angle θ of the coupling 20 with respect to the input shaft 11. Then, the rotation speed Rout of the outer ring 31 becomes larger than the rotation speed Rin of the inner ring 32 (Rin <Rout), and the output shaft 12 that is the outer ring 31 is idled for a while by the inertia (see FIG. 5F). As a result, the output shaft 12 stops at a forward rotation stop angle α1 larger than the forward rotation stop angle β1 of the input shaft 11. At this time, the holding torque required for the input shaft 11 is equal to the torque applied to the output shaft 12 from the outside.
As shown in FIG. 12A, the rotation angle α of the output shaft 12 due to inertia (rotational inertia force) increases as the rotational speed n of the input shaft 11 increases. Further, the rotation angle α of the output shaft 12 becomes the maximum at the maximum use rotation speed nmax of the input shaft 11.

Next, a control method of the power transmission device 10 of the present embodiment will be described. This control method is characterized in that an “output shaft holding process” is executed in order to reduce the power consumption of the motor 17 required for holding the output shaft 12.
The “output shaft holding process” will be described with reference to the flowchart of FIG. 10 and the timing chart of FIG. In the following description of the flowchart, the symbol S indicates “step”.

When holding the output shaft 12, the control device 16 (see FIG. 4) determines whether or not “holding from normal rotation” (S10). In the case of “holding from reverse rotation” (S10: NO), the process proceeds to S40. On the other hand, in the case of “holding from forward rotation” (S10: YES), the control device 16 outputs a reverse rotation command Sfr to the motor 17 at time tfr (S20).
Then, since the input shaft 11 shifts from normal rotation to reverse rotation, the one-way clutch 30 is in an idling state. However, in the two-way clutch 50, the idling state continues immediately after time tfr because the rotation speed Sout of the output side countershaft 52 is still larger than the rotation speed Sin of the input side countershaft 51 (Sin <Sout). Therefore, both the one-way clutch 30 and the two-way clutch 50 are in the idling state, and the output shaft 12 rotates forward while the rotation speed gradually decreases.

  Thereafter, when the input side countershaft 51 reverses λ2 that is the switching angle of the two-way clutch 50, the two-way clutch 50 enters the power transmission state shown in FIG. 6B, and the output shaft 12 starts to reverse. At this time, the rotational torque in the reverse direction of the input shaft 11 is transmitted to the output shaft 12 with a magnitude Zio times the rotational torque during forward rotation.

  Here, the time from the time tfr when the control device 16 outputs the reverse rotation command Sfr from the normal rotation to the input shaft 11 to the time tx when the output shaft 12 shifts from the normal rotation to the reverse rotation is referred to as a “reverse rotation switching time Tx”. . As shown in FIG. 12B, the reverse rotation switching time Tx becomes longer as the rotational speed n of the input shaft 11 is larger. Further, the reverse rotation switching time Tx becomes the maximum at the maximum use rotation speed nmax of the input shaft 11.

  In the control method of the power transmission device 10 according to the present embodiment, a “switching confirmation time Tc” that is equal to or longer than the reverse rotation switching time Tx at the maximum operating rotational speed nmax of the input shaft 11 is set (see FIG. 12B). Then, the control device 16 determines whether or not the switching confirmation time Tc has elapsed from the time tfr (S30), and at the time trs when it is recognized that the switching confirmation time Tc has elapsed (S30: YES) The stop command Srs is output (S40).

  Then, the input shaft 11 directly connected to the shaft of the motor 17 stops at the reverse rotation stop angle β2. The output shaft 12 follows the input shaft 11 and stops at the reverse rotation stop angle α2. At this time, the holding torque required for the input shaft 11 is (1 / Zio) of the torque applied to the output shaft 12 from the outside.

  As described above, in the control method of the power transmission device 10 of the present embodiment, when the output shaft 12 is held from the normal rotation, the input shaft 11 is temporarily switched from the normal rotation to the reverse rotation. Then, after “switching confirmation time Tc” elapses, “second stage” of switching the input shaft 11 from reverse rotation to stop is included. Thus, by holding the output shaft 12 stopped from the reverse rotation, the holding torque can be reduced to (1 / Zio) as compared to the case where the output shaft 12 is stopped and held from the normal rotation. Therefore, the power consumption of the motor 17 can be reduced.

(Other embodiments)
(A) In the above embodiment, the control device 16 controls the motor 17 at the time trs when the switching confirmation time Tc elapses from the time tfr when the input shaft 11 is switched from the normal rotation to the reverse rotation regardless of the rotation speed of the input shaft 11. A stop command Srs is output. In another embodiment, the control device 16 stores a map (FIG. 12B) showing the relationship between the rotational speed of the input shaft 11 and the reverse rotation switching time Tx, and includes a rotational speed detection means. The stop command Srs may be output to the motor 17 by estimating an appropriate switching time according to the acquired rotation speed from the map.
(A) After switching the input shaft 11 from normal rotation to reverse rotation, the control device 16 recognizes that the rotation direction of the output shaft 12 has changed from normal rotation to reverse rotation, and outputs a stop command Srs to the motor 17. May be.

(C) In the above embodiment, the CW direction as viewed from the input shaft 11 side is defined as “forward rotation”, and the CCW direction as viewed from the input shaft 11 side is defined as “reverse rotation”.
(D) The method for controlling the power transmission device of the present invention is not limited to a variable compression ratio engine, and can be applied to various devices that change the transmission ratio and transmission torque between the input shaft and the output shaft by forward and reverse rotation.
As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

10: Power transmission device,
11 ・ ・ ・ Input shaft,
12 ... Output shaft,
13 ... intermediate shaft,
16 ・ ・ ・ Control device 17 ・ ・ ・ Motor (drive means),
20 ・ ・ ・ Coupling,
30 ・ ・ ・ One-way clutch (unidirectional rotational force transmission member),
31 ・ ・ ・ Outer ring,
32 ... inner ring,
41 ・ ・ ・ Input gear (input transmission member),
42 ... 1st gear (1st transmission member),
43 ... 2nd gear (second transmission member),
44 ... Output gear (output transmission member),
50 ... Two-way clutch (two-way rotational force transmission member),
51 ・ ・ ・ Input side countershaft, outer ring,
52 ... Output side countershaft, inner ring,
Sfs ... Stop command (from forward rotation),
Sfr ... reverse rotation command (from forward rotation),
Srs ... Stop command (from reverse rotation),
Tc: switching confirmation time,
Tx ... Reverse switching time.

Claims (4)

When the rotational force of the input shaft driven by the driving means is transmitted to the output shaft, the rotation of the input shaft in one rotational direction is forward rotation, and the rotation of the input shaft in the other rotational direction is reverse rotation, When the input shaft is rotating forward, the output shaft is rotated at the same speed as the rotation of the input shaft, and when the input shaft is rotating reversely, the output shaft is rotated at a reduced speed relative to the rotation of the input shaft,
An input transmission member fixed to the input shaft and rotating together with the input shaft;
A first transmission member that is fixed to an input-side countershaft provided on a shaft different from the input shaft, is rotated by the rotation of the input transmission member and rotates together with the input-side countershaft;
A second transmission member fixed to an output side auxiliary shaft provided on a shaft different from the output shaft and rotating together with the output side auxiliary shaft;
An output transmission member that is fixed to the output shaft and that rotates with the output shaft by transmitting the rotation of the second transmission member;
A one-way rotational force transmitting member capable of transmitting a normal rotation force of the input shaft to the output shaft during normal rotation of the input shaft and allowing the output shaft to idle during reverse rotation of the input shaft;
A two-way rotational force transmission member capable of transmitting the rotational force of the input-side secondary shaft to the output-side secondary shaft and allowing the input-side secondary shaft to idle with respect to the rotational force of the output-side secondary shaft;
With
During normal rotation of the input shaft, the normal rotation force of the input shaft is transmitted to the output shaft via the one-way rotational force transmitting member,
When the input shaft is reversely rotated, the reverse rotation force of the input shaft is the input transmission member, the first transmission member, the input side auxiliary shaft, the two-way rotational force transmission member, the output side auxiliary shaft, and the second transmission member. A control method of a power transmission device that is transmitted to the output shaft via the output transmission member,
When maintaining the rotation angle with respect to the external force applied to the output shaft in a state where the output shaft is stopped from normal rotation,
A first step of switching the input shaft from forward rotation to reverse rotation by the driving means;
Subsequent to the first stage, in the two-way rotational force transmission member, the rotational force of the input-side countershaft is changed from the idling state in which the output-side countershaft idles with respect to the rotational force of the input-side countershaft. A second stage of switching the input shaft from reverse rotation to stop by the drive means after switching to a power transmission state transmitted to the collateral shaft;
A control method for a power transmission device. The bidirectional torque transmission member is
When the rotation speed of the output side countershaft is greater than the rotation speed of the input side countershaft, the idling state occurs,
2. The method of controlling a power transmission device according to claim 1, wherein the power transmission state is established when the rotational speed of the output side secondary shaft is smaller than the rotational speed of the input side secondary shaft.   3. The control of the power transmission device according to claim 2, wherein the drive unit switches the input shaft from reverse rotation to stop after a predetermined delay time has elapsed since the time when the input shaft was switched from normal rotation to reverse rotation. Method.   The predetermined delay time is from the time when the input shaft is switched from normal rotation to reverse rotation at the maximum operating rotational speed of the input shaft until the rotational speed of the output side secondary shaft becomes equal to the rotational speed of the input side secondary shaft. 4. The method of controlling a power transmission device according to claim 3, wherein the time is longer than the time.

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