JP3023591U - Flap parking device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To prevent damage to the bottom of a vehicle, improve safety, prevent damage to a device, facilitate installation work, improve reliability, and reduce the size of the entire device. SOLUTION: The flap operating means is made expandable and contractable by springs 20 and 21, allowing the flap to rotate in the upright direction when the flap is lying down, and rotating the flap in the fallen direction so as to correspond to the height of the vehicle bottom when the flap is upright. Allow movement. Power is transmitted by a tension spring 29 for power transmission which is interposed between the gear 25 and the crank arm 14 of the operating means by being driven by the motor 38 so as to be wound around the outer periphery of the bearing 28. The gear 25 is further rotated slightly in the standing state of the flaps, and the actuating means is locked by the locking means such as the ratchet wheel 49 and the ratchet pawl 56. When the flap is overturned, the lock means is released first. When a predetermined load is applied to the flap in the locked state in the locked state, the power transmission to the locking means is shut off by the transmission limiting means such as the clutch plate receiving wheel 31 and the clutch plate 48.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

 The present invention relates to a flap parking device used for unmanned parking management.

[0002]

[Prior art]

 Conventionally, as a flap parking apparatus of this type, for example, as described in Japanese Patent Laid-Open No. 60-19875, an external force acts on the flap in the power transmission path of the motor when the flap is upright and when the flap is in the fall direction. There is known a structure in which a coil spring is wound around this fixing member so that the surface pressure with the fixing member is increased.

According to this flap parking lot, even if the flap is overloaded and the impact force of these can be mitigated even when the motor is started, the stress level generated in each part can be reduced, and by extension, each part can be reduced. It is possible to suppress fatigue and impact damage of the vehicle, and the continuously variable lock structure holds and fixes the flap at a height of the ground according to the height of the vehicle, regardless of the height of the vehicle. It is possible to prevent unauthorized escape.

[0004]

[Problems to be solved by the device]

 However, in the configuration of the above-mentioned conventional example, since the coil spring is wound so that the surface pressure with the fixing member rises when the flap is erected and when an external force acts on the flap in the collapse direction, the impact force Not only is it difficult to set the strength of the above-mentioned surface pressure to alleviate, suppress impact damage, and hold and fix the flap at an arbitrary height, but also the size of the entire device increases. In addition, in any of the conventional flap parking devices, there is a problem that maintenance is inconvenient because the entire device is not mounted on the base.

The present invention solves the above-mentioned conventional problems, and can hold the flap without damaging the bottom of the vehicle according to the height of the bottom of the vehicle, and also, when the flap falls down, the flap can be held between the ground and the ground. It is possible to prevent injury even if you pinch your foot etc. to improve safety, and to lower the flap due to the load when the car forcibly rides on the flap when standing up. By doing so, it is possible to prevent damage to the device and the bottom of the vehicle, to facilitate the installation work, and to operate the flap reliably with a simple structure to ensure the reliability of the above functions. It is an object of the present invention to provide a flap parking device that can be improved and can be made compact as a whole.

[0006]

[Means for Solving the Problems]

 The technical means of the present invention for achieving the above object is to allow the flap, which is supported in an undulating manner, to rotate in the standing direction against the elastic biasing force when the flap falls, and to elastically move the flap when the flap stands. A flap actuating means having an expansion and contraction mechanism that allows rotation in the fall direction so as to correspond to the height of the vehicle bottom against the biasing force, a driving motor for raising and lowering the flap, and a motor for this motor. A gear mechanism for transmitting power to the actuating means by driving, and a power transmitting means having a tension spring for power transmission interposed so as to be wound around the outer periphery of the shaft portion between the gear mechanism and the actuating means. When the flap is erected, the operation of the actuating means is stopped while the gear mechanism rotates a little further in the erection direction of the flap against the tensile force of the tension spring. Few mechanisms When a predetermined load in the fall direction is applied to the locking means for releasing the operating means to the operable state during the reverse rotation and the flap in the upright state in the locked state of the locking means, Transmission limiting means capable of interrupting power transmission to the locking means.

In the above technical means, the power transmission means has an auxiliary spring for urging the actuation means so as to follow the tension force of the tension spring for power transmission to actuate the flap when the flap is erected. preferable.

Further, the expansion / contraction mechanism of the actuating means includes an expansion / contraction portion, a first spring for urging the expansion / contraction portion in a direction to extend the elastic member, and an elastic member for urging the expansion / contraction portion in a direction to contract the elastic member. It is possible to use a ratchet mechanism as the locking means and a clutch mechanism as the transmission limiting means, provided with a second spring set so that the force is weakened.

Further, it is preferable that the actuating means, the driving motor, the power transmitting means, the locking means and the transmission limiting means are mounted on the base and housed in the box.

According to the present invention configured as described above, by driving the motor in either direction, the flap is erected via the power transmission means and the actuation means, and is brought into the erected state by the locking means. It is possible to hold it, or to unlock the actuating means by the locking means, and to lay down the flap via the power transmission means and the actuating means. If the bottom of the flap is low when the flaps are erected, the expansion and contraction mechanism can regulate the rotation of the flap according to the height of the bottom of the flap, or the height of the bottom of the flap can be lowered after parking due to an increase in luggage, etc. If it does, the expansion mechanism allows the flaps to be tilted according to the height of the vehicle bottom. In addition, even if the foot or the like is caught when the flap is laid down, the expansion and contraction mechanism can prevent the flap from descending. In addition, when the vehicle tries to forcibly ride on the flap while the flap is standing, the power transmission from the actuating means to the locking means can be interrupted by the transmission limiting means and the flap can be lowered by the load of the vehicle, etc. After passing the vehicle, the tension force of the tension spring allows the flap to be erected via the actuating means. In addition, when the flap is in the laid state, the flap can be freely raised by the expansion and contraction mechanism, which facilitates handling. Further, the gear mechanism of the power transmission mechanism and the actuation means are linked by a tension spring for power transmission provided so as to be wound around the outer periphery of the shaft portion, and the actuation means, the locking means, and the transmission limiting means having an expansion / contraction mechanism are combined. Therefore, each operation of the flap can be reliably performed with a simple configuration.

[0011]

[Embodiment of device]

 An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 show a flap parking apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of a box body with an upper surface removed, FIG. 2 is a partially cutaway front view, and FIG. 3 is AA of FIG. FIG. 4 is a partially cutaway enlarged side view taken along the line, FIG. 4 is a view taken along the line BB of FIG. 3, and FIG. 5 is a partial bottom view of FIG.

In FIGS. 1 to 4, 1 is a flap, 2 is a drive device for the flap 1, and 3 is a box body made of sheet metal for housing a drive device 2. A base 4 is detachably attached to the upper surface of the bottom plate 3c of the box body 3 with screws 5, and the entire drive device 2 is mounted on the base 4.

The bearing member 6 is attached to the grounding base 7 on the lower side of the box body 3 through the hole 3d of the bottom plate 3c of the box body 3, and the hole 3b formed in the bearing member 6 and the side plate 3a of the box body 3. The shaft 8 fixed to the flap 1 is inserted therethrough. A base of a crank arm 9 is fixed to the shaft 8, and a piece 10 is rotatably connected to the tip of the crank arm 9 by a shaft 11. A small-diameter portion on one side of the operating rod 13 is slidably inserted into a hole 12 formed in the piece 10, and a tip end portion of a crank arm 14 is rotatably connected to the other end of the operating rod 13. A bearing member 15 is fixed on the middle portion of both long side edges of the base 4, and both end portions of a rotary shaft 16 are rotatably supported by both bearing members 15. The base of the crank arm 14 is fitted on the end of the rotary shaft 16 so as to rotate integrally with the key 17 and the key groove 18.

A compression spring 20 is interposed between the large-diameter step portion 19 in the middle portion of the operating rod 13 and the piece 10, and a tension spring is provided between the side portion of the intermediate portion of the operating rod 13 and the side portion of the piece 10. It is connected by a spring 21. The tension spring 21 is set so that the biasing force thereof is weaker than that of the compression spring 20, and when the flap 1 is unloaded, the elasticity of the compression spring 20 causes the intermediate diameter step portion 22 of the operating rod 13 to be slightly separated from the bridge 10. It is set. Therefore, when the bridge 10 is moved rearward (on the side of the flap 1) of the operating rod 13, the repulsive force of the compression spring 20 and the pressing force of the intermediate diameter step portion 22 due to the compression of the compression spring 20 cause the piece 10 to be pressed. The bridge 10 and the crank arm 9 are rotated, and the clap 1 connected to the crank arm 9 by the shaft 8 is rotated in the standing direction. On the contrary, when the operating rod 13 is operated forward (opposite to the flap 1), the shaft 8 of the flap 1, the crank arm 9 and the bridge 10 are flapped by the tensile force of the tension spring 21 and the weight of the flap 1. It is possible to rotate the flap 1 in the falling direction of the flap 1. At this time, it is possible to suppress the falling of the flap 1 by sliding the bridge 10 against the operating rod 13 against the tensile force of the tension spring 21. Has become. As described above, the operating means of the flap 1 has an expanding / contracting portion formed by the bridge 10 and the operating rod 13 and an expanding / contracting mechanism formed by the compression spring 20, the tension spring 21 and the like in the intermediate portion.

A wheel 23 is rotatably supported on the rotating shaft 16 via a bearing 24, and a gear 25 is fixed to the wheel 23. A spring hook 26 projects from the side of the base of the crank arm 14, and a spring hook 27 projects from the side of the wheel 23 opposite to the spring hook 26 with the rotating shaft 16 interposed therebetween. A tension spring 29 for power transmission is stretched around the outer circumference of a bearing 28 provided on the outer circumference of the small diameter portion of the wheel 23. A protrusion 30 is integrally provided on the wheel 23 at a position closer to the tensioning direction of the tension spring 29 than the spring hook 26 (see FIGS. 4 and 5). Then, when the flap 1 is erected, the gear 25, the wheel 23, etc. are rotated clockwise in FIG. 4, whereby the crank arm 14 is rotated clockwise by the tensile force of the tension spring 29, and the operating rod 13 is moved as described above. Is designed to be driven backwards. On the contrary, when the flap 1 falls down, the gear 25, the wheel 23, etc. are rotated counterclockwise in FIG. 4, so that the tension force of the tension spring 29 is released and the spring hook 26 is pressed by the protrusion 30. At the same time, as described above, the operating rod 13 is moved forward by the weight of the flap 1, so that the crank arm 14 is rotated counterclockwise. At this time, the tension bar 29 is wound around the outer circumference of the bearing 28, so that the expansion and contraction thereof can be easily performed.

A clutch plate receiving wheel 31 is fixed on the rotating shaft 16. A spring hook 32 is provided so as to project from the clutch plate receiving wheel 31, and an auxiliary spring 34, which is a tension spring, is stretched between the spring hook 32 and the spring hook 33 fixed on the base 4. The auxiliary spring 34 urges the clutch plate receiving wheel 31, the rotary shaft 16, and the crank arm 14 clockwise in FIG. 4, and the urging force causes the gear 25 and the like to rise when the flap 1 stands up as described above. The crank arm 14 smoothly follows when is rotated clockwise.

A rotating shaft 36 parallel to the rotating shaft 16 is rotatably supported by a pair of bearing members 35 fixed on the base 4, and a gear 37 fixed on the rotating shaft 36 meshes with the gear 25. Has been done. A motor 38 is mounted on the base 4, a rotating shaft of the motor 38 is connected to a reduction gear mechanism 39, and a gear 41 is fixed on an output shaft 40 of the reduction gear mechanism 39. The gear 41 is meshed with a gear 42 fixed on the rotary shaft 36. Then, by rotating the rotating shaft of the motor 38 in either direction, the rotating shaft 36 is rotated in either direction via the reduction mechanism 39 and the gears 41, 42, and the rotating shaft 36 rotates. Through the gear 37, the gear 25 and the like can be rotated in either direction as described above. Cams 43 and 44 are fixed on the rotary shaft 36, limit switches 45 and 46 are provided on the base 4 corresponding to the cams 43 and 44, respectively, by the cams 43 and 44 when the flap 1 stands up and falls. The limit switches 45 and 46 are operated so that the drive of the motor 38 is stopped.

A clutch plate 48, a ratchet wheel 49, a disc spring 50, and a thrust bearing 51 are sequentially fitted on the small diameter portion 47 of the clutch plate receiving wheel 31, and a screw portion 52 formed at the end of the small diameter portion 47. A nut 53 is screwed to the ratchet wheel 50, and the ratchet wheel 49 and the clutch plate 48 are pressed against the clutch plate receiving wheel 31 with a constant torque by the repulsive elasticity of the disc spring 50, so that they are integrated with the rotary shaft 16 and the crank arm 14. It can rotate.

A base 54 is supported on the base 4 so as to be slidable in a direction perpendicular to the rotary shaft 16, and the base 54 is biased by a tension spring 55 toward the side away from the ratchet wheel 49. The base of the ratchet pawl 56 is rotatably supported on the lower portion of the base 54, and is biased to be engaged with the teeth of the ratchet wheel 49. A bearing 57 is rotatably supported on the side of the middle portion of the base 54, and a cam 58 is fixed on the rotating shaft 36 in correspondence with the bearing 57. Then, the rotating shaft 36 is rotated as described above, the bearing 53 is released from the cam 58 at the terminal end where the flap 1 is erected, the base 54 and the ratchet pawl 56 are retracted by the elasticity of the tension spring 55, and the ratchet pawl 56 is released. The ratchet wheel 49 is engaged with the teeth so that the flap 1 is locked so that its rotation in the falling direction is restricted, and conversely, the rotation shaft 36 is rotated, and the cam 58 is rotated when the flap 1 falls down. The bearing 57 is pressed, the base 54 and the ratchet pawl 56 move forward against the elasticity of the tension spring 55, the ratchet pawl 56 separates from the teeth of the ratchet wheel 49, and the ratchet wheel 49, the rotary shaft 16, the crank arm. 14 and the like can be freely rotated in the direction in which the flap 1 falls. When the vehicle is forcibly ridden on the flap 1 in the upright state and a load of, for example, about 200 kg is applied, the clutch plate 48, the ratchet wheel 49 and the clutch plate receiving wheel 31, the rotary shaft are rotated. 16, the crank arm 14 and the like can be freely rotated, and accordingly, the lock force is set so as not to be transmitted to the locking means including the ratchet wheel 49, the ratchet pawl 56 and the like.

In the flap parking apparatus configured as described above, the box 1 is fixed to the parking lot together with the grounding base 7 therebelow by anchor bolts (not shown) or the like, and the end of the shaft 8 of the flap 1 is a bearing. It is rotatably supported and used by a bearing member (not shown) similar to the member 6. First, to explain the stand-up operation of the flap 1, the vehicle enters the parking lot, stops while the front wheels pass over the flap 1 on which the vehicle is lying, and by detecting this with a sensor (not shown), The motor 38 is driven by this detection signal. By driving the motor 38, the rotation shaft 36 is rotated via the speed reduction mechanism 39 and the gears 41 and 42, and further, the gear 25 and the wheel 23 are freely rotated in the clockwise direction in FIG. 4 with respect to the rotation shaft 16 via the gear 35. Let Along with this, the crank arm 14, the rotary shaft 16, the clutch plate receiving wheel 31, the clutch plate 48, the ratchet wheel 49, etc. rotate clockwise by the tensile force of the tension spring 29 as described above. As the crank arm 14 rotates, the operating rod 13 is operated rearward as described above (see the chain line in FIG. 2) to rotate the bridge 10, the crank arm 9, the shaft 8 and the flap 1 in the upright direction. At this time, since the clutch arm 14 is made to smoothly follow the rotation of the wheel 23 by the auxiliary spring 34 as described above, the flap 1 can be smoothly rotated in the standing direction.

When the flap 1 comes into contact with a stopper (not shown) and stands up, the rearward movement of the crank arm 14 is restricted by the standup of the flap 1, so that the gear 25, the wheel 23, etc. are moved slightly clockwise. Rotate and hold tension spring 29 in an extended state. Then, as described above, the bearing 57 is released by the rotation of the cam 58, the base 54 and the ratchet pawl 56 are retracted by the elasticity of the tension spring 55, and the ratchet pawl 56 is engaged with the teeth of the ratchet wheel 49 to reverse the rotation. It is possible to prevent and keep the flap 1 in the upright state. In this state, the cam 43 and the limit switch 45 detect the rising of the flap 1 and stop the driving of the motor 38.

When the flap 1 stands up as described above, and when the vehicle bottom is low, if the upper edge of the flap 1 abuts the vehicle bottom and the like, the operating rod 13 causes the elasticity of the compression spring 20 to rise as described above. Since the flap 1 can be slid rearward against the piece 10 and the flap 1 can be regulated so as not to rotate further, damage to the vehicle bottom can be prevented. In addition, when multiple people are riding when parking, the bottom of the vehicle is low and the upper edge of the flap 1 abuts on the bottom of the vehicle. Then, when a person gets out of the car and the bottom of the car rises, the tension spring 29 It is possible to actuate the actuating means such as the crank arm 14 by the pulling force to raise the flap 1 until it comes into contact with the stopper.

Next, the operation of laying down the flap 1 will be described. The user puts a charge corresponding to the parking time into a meter or the like, and drives the motor 38 in the opposite direction to the above according to the detection signal. The motor 38 is driven to rotate the rotary shaft 36 via the speed reduction mechanism 39 and the gears 41 and 42, and further, the gear 25 and the wheel 23 are freely rotated in the counterclockwise direction in FIG. 4 with respect to the rotary shaft 16 via the gear 35. Rotate. Along with this, first, the tension force of the tension spring 29 is released, and the cam 58 reversely rotates and presses the bearing 57 until the protrusion 30 contacts the spring hook 26 of the crank arm 14. 4 and the ratchet pawl 56 are advanced against the elasticity of the tension spring 55, the ratchet pawl 56 is disengaged from the teeth of the ratchet wheel 49, and the ratchet wheel 49 is released. To be able to rotate. Subsequently, the spring hook 26 is pressed by the projection 30, and the crank arm 14, the rotary shaft 16, etc. rotate counterclockwise in FIG. 4 as described above, and the operating rod 13 operates forward (see the solid line in FIG. 2). The crank arm 9 and the bridge 10 are rotated in the same direction as the crank arm 14 by the tension spring 21, and the flap 1 falls down. In this state, the cam 44 and the limit switch 46 detect the fall of the flap 1, and the driving of the motor 38 is stopped.

Even if a foot or the like is sandwiched between the flap 1 and the grounding base 7 when the flap 1 falls down, the tension spring 21 is stretched between the bridge 10 and the operating rod 13 as described above so that it can be expanded and contracted. Therefore, the bridge 10 can be slid against the operating rod 13 against the elasticity of the tension spring 21 to prevent the crank arm 9, the shaft 8 and the flap 1 from rotating toward the laid side, and the foot or the like. It is possible to prevent damage.

Further, after parking, when the vehicle bottom is lowered due to an increase in luggage, an increase in the number of passengers, etc., the flap 1 resists the elasticity of the compression spring 20 to the height of the vehicle bottom in the same manner as described above. Correspondingly, it can fall down and prevent its damage. Further, when the vehicle forcibly rides on the flap 1 while the flap 1 is raised as described above and is functioning as a parking device, the load is increased by the clutch plate receiving wheel 31 and the clutch as described above. By being applied between the plate 48 and the clutch plate 48, the clutch plate receiving wheel 31 slips with respect to the clutch plate 48 and separates the rotating shaft 16 and the ratchet wheel 49, thereby rotating the rotating shaft 16, the crank arm 14, and the like. Since the flap 1 is allowed, the flap 1 can be laid down in the same manner as the laying operation of the flap 1 described above, and damage to the device and damage to the vehicle bottom can be prevented. At this time, the thrust bearing 51 can prevent the nut 53 from acting in the tightening direction.

Further, when the present apparatus is installed in the parking lot, the flap 1 can be raised against the elasticity of the tension spring 21 as in the fall of the flap 1, so that the installation work is facilitated. It can be carried out.

[0027]

[Effect of device]

 As described above, according to the present invention, by driving the motor in either direction, the flap is erected via the power transmission means and the actuation means, and is held in the erected state by the locking means, or is locked. It is possible to unlock the actuating means by means of which the flap can be laid down via the power transmission means and the actuating means. If the bottom of the flap is low when the flaps are erected, the expansion and contraction mechanism can regulate the rotation of the flap according to the height of the bottom of the flap, or the bottom of the flap can be lowered due to an increase in luggage after parking. If it does, the flaps can be tilted according to the height of the vehicle bottom by the expansion mechanism. Therefore, the flap can be held upright without damaging the vehicle bottom. In addition, even if the foot or the like is caught when the flap is laid down, the expansion and contraction mechanism can prevent the flap from descending. Therefore, it is possible to prevent the injury of the foot and the like and improve the safety. In addition, when the vehicle tries to forcibly ride on the flap when the flap is standing, it is possible to lower the flap by the load of the vehicle etc. by cutting off the power transmission from the operating means to the locking means by the transmission limiting means. After the vehicle has passed, the flap can be erected via the actuating means by the tensile force of the tension spring. Therefore, damage to the device and the bottom of the vehicle can be prevented. In addition, when the flap is in the lying state, the flap can be freely raised by the expansion and contraction mechanism, which facilitates handling. Therefore, the installation work in the parking lot can be easily performed. Further, the gear mechanism of the power transmission mechanism and the actuation means are linked by a tension spring for power transmission provided so as to be wound around the outer periphery of the shaft portion, and the actuation means having an expansion / contraction mechanism, the locking means and the transmission limiting means are combined. Therefore, each operation of the flap can be reliably performed with a simple configuration. Therefore, it is possible to make the entire device compact and improve the reliability.

Further, the power transmission means has an auxiliary spring that urges the actuation means to follow the tensile force of the tension spring for power transmission to operate when the flap is erected, so that the flap is erected smoothly. be able to.

Further, by mounting the operating means, the driving motor, the power transmission means, the locking means, and the transmission limiting means on the base, it is possible to convert and reattach the base in the event of a failure, which facilitates maintenance. It can be performed at low cost.

[Brief description of drawings]

FIG. 1 is a plan view showing a flap parking device according to an embodiment of the present invention, in which a top surface of a box body is removed.

FIG. 2 is a partially cutaway front view showing the flap parking device.

FIG. 3 is a partially cutaway enlarged side view of the flap parking device taken along the line AA of FIG. 1.

FIG. 4 is a view of the flap parking device, taken along the line BB of FIG.

5 is a partial bottom view of FIG. 4, showing the flap parking device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 flap 2 drive device 4 base 9 crank arm 10 piece 13 operating rod 14 crank arm 20 compression spring 21 tension spring 23 wheel 25 gear wheel 29 power transmission tension spring 31 clutch plate receiving wheel 34 auxiliary spring 37 gear wheel 38 motor 41 gear wheel 42 Gear 48 Clutch Plate 49 Ratchet Wheel 56 Ratchet Claw

Claims (4)

[Scope of utility model registration request] 1. When a flap supported so that it can rise and fall is allowed to rotate in the standing direction against the elastic biasing force when the flap falls, it corresponds to the height of the bottom of the vehicle against the elastic biasing force when standing up. As described above, a flap actuating means having an expansion / contraction mechanism that allows rotation in the fall direction, a driving motor for raising and lowering the flap, and a gear for transmitting power to the actuating means by driving the motor. Mechanism and power transmission means having a tension spring for power transmission interposed so as to be wound around the outer periphery of the shaft portion between the gear mechanism and the actuation means, and the gear mechanism includes the tension spring when the flap is erected. The operation of the actuating means is stopped in the state of further rotating in the upright direction of the flap against the pulling force of the flap, and the actuating means can be actuated while the gear mechanism rotates a little in the reverse direction when the flap falls. And a locking means for releasing the locking means and a transmission for cutting off power transmission from the actuating means to the locking means when a predetermined load is applied to the flap in the upright state in the locked state of the locking means in the fall direction. A flap parking device with a restricting means. 2. The flap parking apparatus according to claim 1, wherein the power transmission means has an auxiliary spring for urging the operating means so as to follow the tension force of the tension spring for power transmission when the flap is erected. 3. An expansion / contraction mechanism of the actuating means, an expansion / contraction portion, a first spring for urging the expansion / contraction portion in a direction to extend the same, and an expansion / contraction portion in a direction for contracting the expansion / contraction portion. The flap parking apparatus according to claim 1 or 2, further comprising a second spring set so that the force is weakened, the locking means is a ratchet mechanism, and the transmission limiting means is a clutch mechanism. 4. The flap parking apparatus according to claim 1, wherein the operating means, the driving motor, the power transmitting means, the locking means and the transmission limiting means are mounted on a base and housed in a box. .