JP2008128262A - Reverse rotation preventing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the reverse rotation of a motor due to reaction from a load side during powering the motor off without separating a driving shaft. <P>SOLUTION: This reverse rotation preventing mechanism 120 holds a stopper 124 in a body 122 movably in the direction of leaving the motor driving shaft 110 at a predetermined distance, and energizes the stopper 124 toward the motor driving shaft 110 with a pressure spring 126. A sprag 128 functioning as a lock member is arranged between the motor driving shaft 110 and the stopper 124 so as to be energized to a neutral position by a neutral spring 130. The sprag 128 maximizes the thrust of the pressure spring 126 on the motor driving shaft 110 at the neutral position and reduces the thrust on the motor driving shaft 110 as leaving the neutral position. The spring load of the pressure spring 126 is set so that friction torque on the motor driving shaft 110 at the neutral position of the sprag 128 is greater than reverse torque from the load side and smaller than the driving torque of the motor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a reverse rotation prevention mechanism used for a four-wheel drive vehicle in which a shift operation of an auxiliary transmission mechanism is driven by a motor.

  In a driving force distribution device for a four-wheel drive vehicle with a subtransmission mechanism, the subtransmission mechanism is generally shifted when the vehicle is stopped and the transmission is in a neutral position.

  In this case, since the input shaft of the driving force distribution device for a four-wheel drive vehicle is not rotating, the shift operation may not be completed because the phase of the meshing clutch for switching does not match.

  When the driver shifts directly by manual operation, the driver can recognize this state and adjust the meshing phase by connecting the clutch of the transmission. The operation remains stopped.

If a current is continuously supplied to the motor in this state, the motor will overheat, which is dangerous. Therefore, a stroke absorbing mechanism called a waiting mechanism is provided somewhere in the middle of the motor and the shift mechanism.
Even when the load side is stopped, this waiting mechanism allows the input side to move by contracting the spring, and even when the shifting operation is stopped halfway because the phase of the meshing clutch is not matched. The input side can be moved to the original shift completion position (Patent Document 1).

  However, in this state, since the spring of the waiting mechanism is compressed, a load acts to return the input side to the original state by the spring. In order to turn off the motor and maintain this state, a function is required so that the input side does not return to its original state even when a spring load is applied.

  If the input side does not return to the original state, the shift is completed when the vehicle starts and the mesh clutch phase is matched, and the vehicle can run.

  In general, a shift actuator is a combination of a motor and a worm speed reducer. When the motor is driven from the motor, the efficiency of the worm speed reducer is very low when it is reversed from the load side. There is an effect to.

  Due to this effect, even when the waiting mechanism is operating, it is possible to turn off electricity and wait when the motor is moved to the shift completion position.

  However, as the engine displacement is increased, the switching force and the waiting mechanism load of the auxiliary transmission mechanism are also increased, and the reverse rotation cannot be prevented only by the worm reducer. Therefore, it is necessary to provide a mechanism for preventing reverse rotation somewhere between the motor and the waiting mechanism.

  As an actuator provided with a reverse rotation prevention mechanism for preventing the rotation of the motor due to the reaction force applied from the load side, there is an actuator shown in FIG. 9, for example.

  In FIG. 9, the drive shaft 202 of the motor 200 is connected to a load-side drive shaft 206 divided via a reverse rotation prevention mechanism 204, and a worm gear 208 provided integrally with the load-side drive shaft 206 is engaged with the worm wheel gear 210. ing. The worm wheel gear 210 is coupled to a shift control mechanism.

  The drive shaft 202 of the motor 200 is supported by bearings 211 and 212, and the divided load side drive shaft 206 is supported by bearings 213 and 214. A thrust bearing 215 is provided at the shaft end of the drive shaft 202. A thrust bearing 216 is provided at the abutting portion of the load side drive shaft 206, and a thrust bearing 218 is provided at the shaft end of the load side drive shaft 206.

  Here, the rotation of the motor 200 is transmitted to the load side by the worm gear mechanism. Normally, the worm gear mechanism receives the reaction force from the load side, and the worm wheel gear 210 prevents the reverse rotation by meshing with the worm gear 208 even if it tries to reverse. it can.

  However, in reality, if the reaction force is continuously received from the load side, the reverse rotation is suppressed by the worm gear mechanism, but it is not perfect, and the motor 200 reverses little by little due to the reaction force from the load side, The spring force held by the waiting mechanism is reduced. For this reason, a reverse rotation prevention mechanism 204 is provided between the worm gear mechanism and the motor 200 to prevent reverse rotation due to a reaction force from the load side that is not partitioned by the worm gear mechanism.

  FIG. 10 shows an example of a conventional anti-reverse mechanism 204 provided in the actuator of FIG. 10A is a cross-sectional view of the reverse rotation prevention mechanism cut in the radial direction, and FIG. 10B shows a cross-sectional view cut in the axial direction.

  10A, the reverse rotation prevention mechanism 204 is fixed to the input member 268 fixed to the drive shaft 202 of the motor as the input shaft, the output member 270 fixed to the load side drive shaft 206 as the output shaft, and the case. The lock ring 272, the roller holder 274 disposed with a predetermined friction inside the lock ring 272, and rotatably held by the roller holder 274 with respect to the output member 270 through a predetermined gap at the neutral position shown in the figure. The roller 276 is arranged.

  The output member 270 has three radiating arm portions 270a in the outer circumferential direction from the center portion where the load side drive shaft 206 is mounted, and a linear cam surface 270b in a direction perpendicular to the radiating axis line is formed at the tip of the radiating arm portion 270a. Yes. The roller holder 274 is rotatably held on the inner diameter portion of the lock ring 272 with a slight friction, and has a shape extending radially from the radiation arm portion 270a of the output member 270 through a predetermined gap. A portion 274a is formed on the inner periphery.

  A roller 276 is rotatably supported at the center of the overhanging portion 274a of the roller retainer 274, and the inner end of the roller 276 is positioned at a neutral position from the straight surface facing the straight cam surface 270b of the overhanging portion 274a. A predetermined gap is formed between the output member 270 and the straight cam surface 270b.

  The input member 268 has claw portions 268a arranged in three spaces partitioned by the radiation arm portion 270a of the output member 270 and the overhang portion 274a of the roller retainer 274, and the claw portion 268a is shown in FIG. As shown in the cross section, a radial shape having a radial length from the radiating arm portion 270a of the output member 270 to the overhang portion 274a of the roller retainer 274 is provided.

  FIG. 11 is an explanatory diagram when the reverse rotation force is applied from the load side of FIG. 10 and when the motor is driven. FIG. 11A shows the reverse rotation prevention operation when the output member 270 reverses in the direction of the arrow in response to the reaction force from the load side. When a driving force in the reverse rotation direction is applied to the output member 270 by a reaction force from the load side, there is a slight friction between the lock ring 272 and the roller holder 274, so that the output member 270 precedes the roller 276. And rotate in the direction of the arrow.

  For this reason, the neutral relationship between the roller 276 and the output member 270 is lost, and there is no gap between the roller 276 and the linear cam surface 270b of the output member 270. The roller 276 is opposite to the rotation direction of the linear cam surface 270b of the output member 270. The cam surface comes into contact and is locked. At this time, the input member 268 may be slightly rotated by the output member 270, but the input member 268 also stops at the position where the output member 270 is locked. This prevents reverse rotation due to the reaction force from the load side applied from the load side drive shaft 206, and prevents reverse rotation due to the reaction force from being applied to the motor 200 even when the current of the motor 200 is cut off.

  FIG. 11B shows the operation when the motor 200 is rotated forward. When the input member 268 is driven in the direction of the arrow by the rotation of the motor 200, the side surface on the rotation side of the claw portion 268a of the input member 268 is the side surface of the radiating arm portion 270a of the input member 268 and the overhang portion 274a of the roller retainer 274. In this case, the driving force from the input member 268 is directly transmitted to the output member 270 while the rollers 276 and the output member 270 are held in the neutral position.

In this case, a gap is formed between the output member 270 and the roller 276, and the roller 276 is idled in the lock ring 272 integrally with the roller holder 274 and is not locked.
JP 2005-022467 A

  However, in such a conventional reverse rotation prevention mechanism, the motor drive shaft and the load side drive shaft must be separated into separate parts, and a separate bearing is also required for the load side drive shaft. However, there is a problem that the number of parts is complicated, the cost is high, and the weight is increased.

  In addition, since it is necessary to arrange a reverse rotation prevention mechanism between the motor drive shaft and the load side drive shaft, when unitized as an actuator having a motor, a reverse rotation prevention mechanism and a worm gear mechanism, the total length of the actuator becomes long, There is a problem that the installation space for incorporation into the driving force distribution device for a four-wheel drive vehicle is large and the size is increased.

The present invention has a simple structure that reliably prevents motor reverse rotation due to a reaction force from the load side when the motor is de-energized without separating the drive shaft, and enables reverse rotation that enables reduction in size and weight and cost. An object is to provide a prevention mechanism.

The present invention provides an anti-reverse mechanism. The reverse rotation prevention mechanism of the present invention is
A first state in which the shaft can be freely rotated clockwise with respect to the body, and reverse rotation is prevented if it is less than a predetermined torque even if it receives counterclockwise torque in that state;
The shaft can rotate freely counterclockwise with respect to the body, and has a second state in which reverse rotation is prevented if the torque is less than a predetermined torque even if it receives a clockwise torque in that state,
When the reverse rotation torque exceeds a predetermined value, the first state is shifted to the second state, or the second state is shifted to the first state.

  The reverse rotation prevention mechanism of the present invention is provided in a driving force distribution device for a four-wheel drive vehicle with a subtransmission mechanism, and is built in an actuator that uses a motor to switch the subtransmission mechanism, and the body is fixed to the actuator housing in a non-rotatable manner. And the shaft is a motor shaft.

Here, the reverse rotation prevention mechanism is
A body that surrounds the axis;
A stopper held in the body at a predetermined distance from the shaft and held free to move away from the shaft;
A pressurizing spring that biases the stopper toward the shaft;
A locking member that is disposed between the shaft and the stopper, maximizes the pressing force against the shaft by the pressurizing spring at the neutral position, and reduces the pressing force against the shaft as it moves away from the neutral position;
A neutral spring that biases the locking member to the neutral position;
With
The spring load of the pressurizing spring is set so that the friction torque acting on the shaft by the pressing force at the neutral position of the lock member is larger than the reverse torque from the load side and smaller than the driving torque of the motor.

  Here, the lock member is constituted by a sprag that decreases in height as it rotates from the neutral position according to the rotation of the shaft. Further, the lock member may be constituted by a roller that reduces the contact height with the stopper as it moves from the neutral position according to the rotation of the shaft.

The reverse rotation prevention mechanism of the present invention uses, for example, a shift mechanism of an auxiliary transmission mechanism provided in a driving force distribution device for a four-wheel drive vehicle as a load.

  According to the present invention, when the energization of the motor is turned off while the auxiliary transmission mechanism is shifted by the motor drive, the lock member of the reverse rotation prevention mechanism moves to the neutral position even if the reverse torque is received from the load side. As a result, it is possible to reliably prevent reverse rotation by generating a friction torque necessary for fixing the motor drive shaft.

  When the reverse rotation prevention mechanism reverses the shift operation by rotating the motor in the reverse direction in the neutral state where the rotation of the motor drive shaft is locked, the motor drive torque exceeds the lock torque. The lock is released by moving the lock member beyond the neutral position to the opposite side.

  Even when the motor is turned off after the shift is reversed, the rotation of the motor drive shaft can be locked against the reverse torque from the load side and held in a fixed state. That is, in both the forward and reverse rotation driving of the motor drive shaft, when the motor energization is turned off, the rotation of the motor drive shaft can be locked against the torque from the load side opposite to the rotation direction so far.

In addition, there is no need to separate the motor drive shaft from the motor side to the load side, the actuator structure consisting of the motor, reverse rotation prevention mechanism and worm gear mechanism is simplified, the number of parts is reduced, the cost is low, and the actuator is lightweight. Can be realized. Furthermore, the total length of the actuator is shortened, and the installation space for the actuator of the power distribution device for a four-wheel drive vehicle can be reduced, thereby reducing the size and weight.

  FIG. 1 is a cross-sectional view showing an embodiment of a driving force distribution device for a four-wheel drive vehicle equipped with a shift waiting mechanism to which the reverse rotation prevention mechanism of the present invention is applied. In FIG. 1, the driving force distribution device for a four-wheel drive vehicle of this embodiment has a case 10, and an input shaft 12 for inputting power from the engine via an automatic transmission or a manual transmission is provided on the left side of the case 10. The input shaft 12 is connected to a rear wheel output shaft 24 as a main output shaft arranged coaxially via the auxiliary transmission mechanism 14.

  The auxiliary transmission mechanism 14 is a planetary gear mechanism including a sun gear 16, a planetary gear 18 provided on the carrier case 20, and a ring gear 22. A clutch gear 54 is provided integrally with the carrier case 20, and a shift operation can be performed correspondingly. A shift gear 52 is arranged. The auxiliary transmission mechanism 14 switches between the H position and the L position.

  The subtransmission mechanism 14 is in the H position when the shift gear 52 is at the illustrated position, and directly connects the sun gear 16 to the rear wheel output shaft 24. The position where the shift gear 52 meshes with the clutch gear 54 is the L position, the ring gear 22 is fixed, and the input rotation of the sun gear 16 is rotated as the rotation of the carrier case 20 with the planetary gear 18 from the clutch gear 54 via the shift gear 52. This is transmitted to the rear wheel output shaft 24.

  A friction clutch 26 is provided coaxially with the rear wheel output shaft 24. The friction clutch 26 has a clutch hub 44 fixed to the rear wheel output shaft 24, and a clutch drum 46 is connected to a sprocket gear 25 provided to be rotatable with respect to the rear wheel output shaft 24. In parallel with the rear wheel output shaft 24, a front wheel output shaft 30 as a secondary output shaft for extracting power to the opposite side is provided in the case 10, and a sprocket gear 31 is formed integrally with the front wheel output shaft 30 for friction. A chain belt 28 is hung and connected to the sprocket gear 25 on the clutch 26 side.

  In such a four-wheel drive vehicle driving force distribution device, the multi-plate clutch 48 provided between the clutch hub 44 and the clutch drum 46 of the friction clutch 26 is disconnected during two-wheel drive, and the input shaft 12 rotates. Is transmitted to the rear wheel output shaft 24 via the auxiliary transmission mechanism 14. During four-wheel drive, the friction clutch 26 is in a connected state, and the power from the input shaft 12 is transmitted through the rear wheel output shaft 24, the friction clutch 26, the sprocket gear 25, the chain belt 28, and the sprocket gear 31 to the front wheel output shaft. 30 is also transmitted.

  For the friction clutch 26, a ball cam mechanism 32 for continuously controlling the clutch pressing force (transmission torque) of a multi-plate clutch 48 provided between the clutch hub 44 and the clutch drum 46 is provided. The ball cam mechanism 32 holds a ball 38 by being sandwiched between ball cam grooves 39 on the cam surfaces of the fixed cam plate 34 and the rotating cam plate 36 that are provided coaxially with the rear wheel output shaft 24.

  A fixed plate 35 is disposed on the right side of the fixed cam plate 34 via a thrust bearing, and a pressing member 42 is disposed on the left side of the rotating cam plate 36 via a thrust bearing.

  When the rotating cam plate 36 is driven to rotate in a fixed direction with respect to the fixed cam plate 34 by an actuator (not shown), the ball cam mechanism 32 receives pressure from the ball 38 inserted in the ball cam groove 39 that is an inclined groove on the opposite surface. Thus, the pressing member 42 is pressed in the axial direction, and the multi-plate clutch 48 of the friction clutch 26 is pressed, whereby the clutch pressing force is increased according to the rotation amount of the drive gear 40.

  An actuator 70 is provided as a drive source for controlling the shift mechanism 50 of the auxiliary transmission mechanism 14. The actuator 70 includes a motor 71 and a speed reducer 72 using a worm gear mechanism, and transmits the reduced speed rotation to the output shaft 73. A shift cylindrical cam 78 is fixed to the output shaft 73.

  The actuator 70 rotates the shift cylindrical cam 78 of the output shaft 73 to move the shift pin 82 in the axial direction by the shift cam groove 96 formed on the outer periphery thereof. For example, the actuator 70 moves from the H position in the auxiliary transmission mechanism 14 shown in the figure. The shift pin 82 can be moved to the right to switch to the L position.

  A waiting mechanism 60 is provided between the shift pin 82 and the shift fork 56 which are shifted in the axial direction by the shift cylindrical cam 78. The waiting mechanism 60 is arranged on the right side of the shift fork 56 fixed to the shift lot 58, and a stopper ring 64 is inserted and fixed to the built-in spring 62 on the right side.

  The waiting mechanism 60 may be in a positional relationship where the shift gear 52 and the clutch gear 54 do not mesh when a shift operation of the shift pin 82 is performed. In this case, the spring 62 is compressed by the shift operation of the shift pin 82 and the spring 62 The shift fork 56 is energized in the shift direction with the force of the power, and when the gear is engaged in the wait state, the shift operation is performed by the force of the spring 62, and the shift operation itself is completed even if the gear is not engaged. I can do it.

  FIG. 2 is an explanatory view showing the actuator shown in FIG. 1 with the reverse rotation prevention mechanism of the present invention. In FIG. 2, the actuator 70 has a motor 71 mounted on the right side of the housing 111, and the motor drive shaft 110 of the motor 71 is rotatably supported with respect to the housing 111 by thrust bearings 115 and 118 and bearings 116 and 117 on both sides. .

  A worm gear 112 is formed integrally with the motor drive shaft 110, and a worm wheel gear 114 fixed to an output shaft 73 orthogonal to the worm gear 112 is engaged with the motor drive shaft 110. An anti-reverse mechanism 120 according to the present invention is incorporated at the front end side of the motor drive shaft 110.

  FIG. 3 is an explanatory view showing an embodiment of the reverse rotation preventing mechanism 120 according to the present invention provided in the actuator 70 of FIG. 3A, the reverse rotation prevention mechanism 120 has a body 122 incorporated in the housing 111 of FIG. 2, and the motor drive shaft 110 is penetrated and stored in the lower opening thereof.

  A stopper 124 is disposed in the body 122, and the stopper 124 is held at a predetermined distance from the motor drive shaft 110 by abutting against the stopper locking portion 132, and in a direction away from the motor drive shaft 110. It is held movably. A pressurizing spring 126 is incorporated in the upper part of the stopper 124 and biases the stopper 124 toward the motor drive shaft 110 side. A sprag 128 that functions as a lock member is disposed between the motor drive shaft 110 and the stopper 124.

  The sprag 128 is biased in a neutral direction by a neutral spring 130. The neutral spring 130 may be a spring structure in which a torch of a U-shaped leaf spring is fixed and legs are disposed on both sides of the sprag 128.

  As shown in FIG. 3B, the sprag 128 is a substantially gourd-shaped member having a drive shaft contact surface 128a formed on the motor drive shaft 110 side and a stopper contact surface 128b formed on the stopper 124 side. The drive shaft contact surface 128a forms a drive shaft contact surface 128a so that a gap between the drive shaft contact surface 128a and the virtual arc 136 increases toward the right or left side from the illustrated neutral position with respect to the virtual arc 136 centered on the point P. Yes.

  That is, the sprag 128 has the highest neutral height H0, which is the height of the contact position at which the stopper 124 in FIG. 3A and the motor drive shaft 110 are in contact with each other in the neutral position. The height passing through the center P of the stopper contact surface 128b and the drive shaft contact surface 128a decreases toward the height H1.

  Such a sprag 128 is arranged between the motor drive shaft 110 and the stopper 124 via the sprag holding portion 134 as shown in FIG. 3A, so that the sprag 128 in the posture shown in FIG. By interposing between the motor drive shaft 110 and the stopper 124 with a neutral height H0 which is the maximum height at the position, the stopper 124 is pushed up against the pressurizing spring 126 from the stopper engaging portion 132, and the pressurizing spring The pressing force to the motor drive shaft 110 by 126 is maximized, and the pressing force is reduced by decreasing the height with respect to the motor drive shaft 110 as the distance from the neutral position increases.

  That is, the sprag 128 functioning as a lock member is reduced in height by rotating from the neutral position in accordance with the rotation of the motor drive shaft 110.

  Here, the lock torque due to the friction acting on the motor drive shaft 110 by the pressing force according to the spring load of the pressurizing spring 126 at the neutral position of the sprag 128 functioning as a lock member is larger than the reverse torque from the load side and the motor The spring load of the pressurizing spring 126 is set to be smaller than the driving torque by 71.

  4 and 5 are explanatory views showing the operation of the reverse rotation prevention mechanism 120 of FIG. FIG. 4A shows a state in which the motor drive shaft 110 is driven in the counterclockwise direction indicated by the arrow 138 by the motor. The sprag 128 biased by the neutral spring 130 toward the neutral position is rotated to the left away from the motor drive shaft 110 as the motor output shaft 110 rotates counterclockwise.

  Since the height of the sprag 128 is lowered as it is rotated from the neutral position, the stopper 124 is lowered and comes into contact with the stopper engaging portion 132, and the spring load of the pressurizing spring 126 is not applied to the sprag 128. The motor output shaft 110 can be rotated in a free state while being rotated leftward.

  The rotation of the motor output shaft 110 in FIG. 4A corresponds to, for example, a shift operation from the H position to the L position. Here, if the motor is turned off after the movement to the L-poge is completed with the waiting mechanism on the shift fork side activated, the reaction force indicated by the arrow 140 in FIG. 4B acts from the shift fork side. . However, since the lock torque by the frictional force 144 determined by the pressing force of the pressurizing spring 126 is larger than the reverse torque by the reaction force, the reverse rotation of the motor is prevented.

  When torque is transmitted from the transmission side to the input shaft 12 in this state, the clutch gear 54 and the shift gear 52 mesh with each other to complete the shift, and the vehicle can travel.

  Thereafter, when the shift is returned from the L position to the H position, the sprag 128 rotates to the right by driving the motor output shaft 110 in the clockwise direction indicated by the arrow 140 as shown in FIG.

  Here, since the rotational torque of the motor output shaft 110 by the motor is larger than the lock torque by the frictional force 144 generated by the pressing force of the pressurizing spring 126, the clock of the motor drive shaft 110 as shown in FIG. The sprag 128 rotates with the rotation of the direction, pushes up the stopper 124 against the pressurizing spring 126 at the neutral position, and further exceeds the neutral position with the motor output shaft 110 as shown in FIG. Rotate left.

  When the sprag 128 rotates beyond the neutral position, the height of the sprag 128 decreases, so that the stopper 124 pressed by the pressurizing spring 126 comes into contact with the stopper engaging portion 126 and the spring load of the pressurizing spring 126 is increased. Is hardly applied to the sprag 128, and the motor drive shaft 110 can rotate in a free state to shift from the L position to the H position.

  In FIG. 5D, when the motor drive shaft 110 is driven in the clockwise direction indicated by the arrow 146 by the motor, the sprag 128 rotates to the left side away from the motor drive shaft 110, and the motor output shaft 110 rotates in a free state.

  FIGS. 5E and 5F show the operation when the rotation direction of the motor drive shaft 110 is opposite to that shown in FIGS. 4A and 4B, that is, counterclockwise as indicated by an arrow 146.

  Here, when the waiting mechanism on the shift fork side is operated by the rotation of the motor output shaft 110 and the motor is turned off, a reaction force indicated by an arrow 148 in FIG. 5 (E) acts from the shift fork side. Since the lock torque by the frictional force 144 determined by the pressing force of the pressurizing spring 120 is larger than the reverse torque, the reverse rotation of the motor is prevented.

  The reverse rotation prevention mechanism of this embodiment completes the shift and turns off the motor regardless of whether the rotation direction of the motor drive shaft 110 that operates the waiting mechanism on the shift fork side is clockwise or counterclockwise. It is possible to lock the reaction force from the waiting mechanism in the state and prevent reverse rotation of the motor.

  FIG. 5F illustrates a case where the shift is performed in the reverse direction after the shift is completed. Here, since the motor torque is larger than the lock torque of the reverse rotation prevention mechanism 120, the motor drive shaft 110 pushes up the cup plug 128 and rotates beyond the neutral position.

  FIG. 6 is an explanatory view showing another embodiment of the reverse rotation preventing mechanism 120 according to the present invention provided in the actuator 70 of FIG. In FIG. 6, the reverse rotation prevention mechanism 120 of the present invention is provided with a body 150 surrounding the motor drive shaft 110, and the body 150 is held at a predetermined distance from the motor drive shaft 110 by positioning by the stopper locking portion 160. 152 is provided so as to be movable in a direction away from the motor drive shaft 110, and a pressurizing spring 154 that biases the motor drive shaft 110 is disposed above the stopper 152.

  In this embodiment, a roller 156 is disposed between the motor drive shaft 110 and the stopper 152, and the roller 156 is urged in a neutral direction by a neutral spring 158. The roller 156 functions as a lock member, and reduces the height of the contact position with respect to the stopper 152 as it moves from the neutral position according to the rotation of the motor drive shaft 110.

  7 and 8 are explanatory views showing the operation of the reverse rotation prevention mechanism of FIG. FIG. 7A shows a state in which the motor drive shaft 110 is driven in the counterclockwise direction indicated by the arrow 162 by the motor. The roller 158 urged toward the neutral position by the neutral spring 158 moves to the left by the counterclockwise rotation of the motor drive shaft 110.

  Since the position of the roller 156 is lowered as it deviates from the neutral position, the stopper 124 comes into contact with the stopper locking portion 132, and the spring load of the pressurizing spring 126 is not applied to the roller 156, so that the motor output shaft 110 rotates in a free state. Can do.

  The rotation of the motor output shaft 110 in FIG. 7A corresponds to, for example, a shift operation from the H position to the L position. When the motor is turned off while the waiting mechanism on the shift fork side is activated, the rotation fork is shown from the shift fork side. The reaction force indicated by the arrow 164 in FIG. However, since the lock torque by the frictional force 166 determined by the pressing force of the pressurizing spring 120 is larger than the reverse torque by this reaction force, the reverse rotation of the motor is prevented.

  When the shift from the L position to the H position is completed after the shift from the H position to the L position is completed, the motor output shaft 110 is driven in the clockwise direction indicated by the arrow 164 as shown in FIG. 156 moves to the right. Here, since the rotational torque of the motor output shaft 110 by the motor is larger than the lock torque generated by the frictional force 166 determined by the pressing force of the pressurizing spring 154, the motor drive shaft 110 as shown in FIG. 7C. The roller 156 moves in accordance with the clockwise rotation of the roller, pushes up the stopper 152 against the pressurizing spring 154 at the neutral position, and further exceeds the neutral position with the motor output shaft 110 as shown in FIG. To the right.

  When the roller 156 moves beyond the neutral position, the position is lowered. Therefore, the stopper 152 pressed by the pressurizing spring 154 comes into contact with the stopper locking portion 160, and the spring load of the pressurizing spring 154 is almost not applied to the roller 156. Without this, the motor drive shaft 110 can rotate and shift in a free state. This state is shown in FIG.

  8E and 8F show the operation when the rotation direction of the motor drive shaft 110 is the reverse direction, that is, the counterclockwise direction as shown by the arrow 168, with respect to FIGS. 7B and 7C.

  Here, when the motor output shaft 110 rotates to actuate the shift fork side waiting mechanism and the motor is turned off, a reaction force in the direction indicated by an arrow 168 in FIG. 8E acts from the shift fork side. Since the lock torque by the frictional force 170 determined by the pressing force of the pressurizing spring 154 is larger than the reverse torque by the force, the reverse rotation of the motor is prevented.

  FIG. 8F shows a case where the shift is performed in the reverse direction after the shift is completed. Here, since the motor torque is larger than the lock torque of the reverse rotation prevention mechanism 120, the motor drive shaft 110 pushes up the roller 156 and rotates beyond the neutral position.

The present invention includes appropriate modifications that do not impair the object and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

Sectional drawing which showed embodiment of the driving force distribution apparatus for four-wheel drive vehicles by this invention Explanatory drawing which extracted and showed the actuator of FIG. 1 provided with the reverse rotation prevention mechanism of this invention. Explanatory drawing which showed embodiment of the reverse rotation prevention mechanism by this invention provided in the actuator of FIG. Explanatory drawing which showed operation | movement of the reverse rotation prevention mechanism of FIG. Explanatory drawing which showed operation | movement of the reverse rotation prevention mechanism following FIG. Explanatory drawing which showed other embodiment of the reverse rotation prevention mechanism by this invention provided in the actuator of FIG. Explanatory drawing which showed operation | movement of the reverse rotation prevention mechanism of FIG. Explanatory drawing which showed operation | movement of the reverse rotation prevention mechanism following FIG. Explanatory drawing of actuator with conventional reverse rotation prevention mechanism Explanatory drawing of the conventional reverse rotation prevention mechanism provided in the actuator of FIG. Explanatory drawing which showed operation | movement of the conventional reverse rotation prevention mechanism of FIG.

Explanation of symbols

10: Case 12: Input shaft 14: Sub transmission mechanism 16: Sun gear 18: Planetary gear 20: Carrier case 22: Ring gear 24: Rear wheel output shaft 25, 31: Sprocket gear 26: Friction clutch 28: Chain belt 30: Front wheel Output shaft 32: Ball cam mechanism 34: Fixed cam plate 35: Fixed plate 36: Rotating cam plate 38: Ball 40: Drive gear 42: Pushing member 44: Clutch hub 46: Clutch drum 48: Multi-plate clutch 50: Shift mechanism 52: Shift gear 53: Clutch gear (H position)
54: Clutch gear (L position)
56: Shift fork (for HL switching)
58: Shift rod 60: Waiting mechanism 62: Spring 64: Stopper ring 70: Actuator 71: Motor 72: Output shaft 78: Shifting cylindrical cam 80: Cam groove 82: Shift pin 120: Reverse rotation prevention mechanism 122, 150: Body 124 152: Stopper 126, 154: Pressurizing spring 128: Sprag 128a: Drive shaft contact surface 128b: Stopper contact surface 130, 158: Neutral spring 132, 160: Stopper locking portion 134: Sprag holding portion 136: Virtual arc 156: Roller

Claims (6)

A first state in which the shaft can freely rotate clockwise with respect to the body, and the reverse rotation is prevented if the torque is less than a predetermined torque even when receiving a counterclockwise torque in that state;
The shaft can rotate freely counterclockwise with respect to the body, and has a second state in which reverse rotation is prevented if the torque is less than a predetermined torque even if it receives clockwise torque in that state,
A reverse rotation prevention mechanism, wherein when the reverse rotation torque exceeds a predetermined value, the first state is shifted to the second state, or the second state is shifted to the first state.
2. The reverse rotation prevention mechanism according to claim 1, wherein the reverse transmission mechanism is provided in a driving force distribution device for a four-wheel drive vehicle with a subtransmission mechanism, and is incorporated in an actuator that switches the subtransmission mechanism with a motor, and the body rotates to the housing of the actuator. A reverse rotation prevention mechanism characterized in that it is fixed impossible and the shaft is a motor shaft.
In the reverse rotation prevention mechanism according to claim 1 or 2,
A body surrounding the axis;
A stopper that is held in the body at a predetermined distance from the shaft, and is held movably in a direction away from the shaft;
A pressurizing spring that biases the stopper toward the shaft;
A locking member that is disposed between the shaft and the stopper, maximizes the pressing force against the shaft by the pressurizing spring at a neutral position, and reduces the pressing force against the shaft as it moves away from the neutral position;
A neutral spring that biases the locking member to a neutral position;
With
The spring load of the pressurizing spring is set so that the friction torque acting on the shaft by the pressing force at the neutral position of the lock member is larger than the reverse torque from the load side and smaller than the driving torque by the motor. An anti-reverse mechanism characterized by that.
4. The anti-reverse mechanism according to claim 3, wherein the lock member comprises a sprag whose height decreases as the shaft rotates from a neutral position in accordance with rotation of the shaft.
4. The reverse rotation preventing mechanism according to claim 3, wherein the lock member is a roller that reduces a contact height with the stopper as it moves from a neutral position in accordance with rotation of the shaft. Reverse rotation prevention mechanism.
  4. The reverse rotation prevention mechanism according to claim 3, wherein the load is a shift mechanism of a subtransmission mechanism provided in a driving force distribution device for a four-wheel drive vehicle.

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