JPH0519633Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention provides an engaging portion that engages with each other in the rotational direction on the intermediate rotating body and the worm gear coaxial therewith, so that the intermediate rotating body and the worm gear can be connected to each other. The present invention relates to a rotation transmission mechanism including a worm gear that can rotate freely relative to each other within a range of 1/2 to 1 rotation, and the worm gear's bite with respect to the worm wheel is released by the inertia force of an intermediate rotating body.

The present invention also relates to a rotation transmission mechanism including a worm gear, which can be assembled without press-fitting an intermediate rotating body or a worm gear onto a shaft.

[Prior Art] A rotation transmission mechanism including a worm gear is often used as a rotation transmission mechanism with a deceleration effect.
One example is the application of video tape recorders to cassette loading devices.

In a cassette loading device, when the cassette is inserted into the cassette holder to a predetermined position, a sensor detects this and starts the motor, transmitting the rotational force of the motor to the worm gear via an intermediate rotating body such as a pulley. The meshing worm wheels are rotated at a reduced speed. This worm wheel
The command is transmitted to the fork member that engages with the cassette holder, and the cassette holder is first pulled in to the deepest position horizontally along the horizontal guide, and then moved vertically downward along the vertical guide to a predetermined cassette loading position. . Then, the position of the cassette holder is detected again by the sensor, and the power to the motor is stopped.

In such a cassette loading device, even if the energization to the motor is immediately stopped after detecting the position of the cassette holder, it is difficult to stop the motor immediately due to the inertia of the rotating part. For this reason, generally, a friction transmission mechanism is interposed in the rotation transmission path from the motor to the worm gear.
The excessive rotation of the motor is absorbed by this friction transmission mechanism.

Furthermore, the worm gear and the intermediate rotating body were attached to the shaft by press fitting, as shown in FIG. That is, a worm gear 101 and a pulley 102 as an intermediate rotating body are press-fitted onto a shaft 103 with a space between them, and the shaft 103 is connected to the worm gear 101 by a pair of bearings 104 and 105.
It is rotatably supported at both sides of. A worm wheel 106 is meshed with the worm gear 101, and an endless belt 107 for transmitting the rotational force of a motor (not shown) is connected to the pulley 102.
Multiply by

[Problems to be Solved by the Invention] Problems in conventional rotation transmission mechanisms of this type will be explained using an example in which they are applied to a VTR cassette loading device.

In other words, the motor that drives the worm gear is
Even if the power supply is stopped, it cannot be stopped immediately due to the inertia of the rotating part. For this reason, as described above, a friction transmission mechanism is generally interposed in the rotation transmission path from the motor to the worm gear to absorb the excessive rotation of the motor. However, even after taking such measures, the rotational force due to the inertia of the motor was still transmitted to the worm gear via the friction transmission mechanism, so the helical teeth of the worm gear, which had rotational force, were forced to stop at the end of operation position. A wedge-shaped phenomenon occurs in which the worm wheel bites into the teeth of the worm wheel. Therefore, when attempting to reversely rotate the motor to perform a cassette unloading operation, it is first necessary to release the helical teeth of the worm gear from biting into the teeth of the worm wheel. I had to keep it high. As a result, problems such as an increase in the size of the motor and an increase in power consumption have arisen.

Therefore, it is an object of the invention of claims 1 and 2 to provide a rotation transmission mechanism including a worm gear that can release the helical teeth from biting into the worm wheel without increasing the starting force of the drive source.

In addition, in conventional rotation transmission mechanisms, the worm gear and intermediate rotating body were attached to the shaft by press-fitting, so a high degree of dimensional accuracy was required for the hole diameter of the intermediate rotating body and worm gear, and the outer diameter of the shaft. This caused a rise in parts costs. Moreover, since a large force is applied to the shaft during the press-fitting process, it is necessary to increase the buckling strength, so it is necessary to increase the outer diameter of the shaft to the extent that it can withstand the pressing force, and to select a material with high strength. As a result, the diameters of the intermediate rotating body and worm gear also become larger, leading to an increase in the size of the entire mechanism, which also contributes to higher costs.

Therefore, it is an object of the invention of claims 3 and 4 to provide a rotation transmission mechanism including a worm gear that can simplify assembly, reduce cost, and reduce size by omitting the press-fitting process.

[Means for Solving the Problems] In the invention according to claims 1 and 2, both or one of the intermediate rotating body and the worm gear are made rotatable about a common axis, and each of the intermediate rotating body and the worm gear is provided with rotational speed relative to the other. The relative rotation amount between the intermediate rotating body and the worm gear is 1/2 ~
An engaging portion is provided that limits each other within the range of one rotation.

Further, in the invention of claims 3 and 4, the intermediate rotating body and the worm gear are loosely fitted to the shaft, both ends of the shaft are received by thrust bearings, and the intermediate rotating body and the worm gear are provided on opposite end faces. The rotation of the intermediate rotary body is transmitted to the worm gear by engaging the engaged portions that are attached to each other.

[Operation] The rotation transmission mechanism according to claims 1 and 2 can be used, for example, in a VTR.
When applied to a cassette loading device such as Even if the worm wheel wedges into the teeth, if the intermediate rotating body is rotated in the opposite direction, the intermediate rotating body will rotate more than 1/2 revolution and the inertia will increase due to the rise in rotational speed. Since the engaging portion collides with the engaging portion of the worm gear from the opposite direction, this collision easily eliminates the tooth digging phenomenon.

In claims 3 and 4, the worm gear and the intermediate rotating body are attached to the shaft by loosely fitting their center holes onto the shaft, and no press-fitting step is required. Furthermore, assembly of the rotation transmission mechanism is completed by simply receiving both ends of the shaft with thrust bearings.

[Embodiment] Fig. 1 shows an embodiment in which the rotation transmission mechanism of the present invention is applied to a cassette loading device for a VTR. A horizontal guide groove 3 and a vertical guide groove 4 are continuously provided to guide the device to the position. Also,
A rotation transmission mechanism 6 including a worm gear 5 is attached to the main body side plate 1 .

The rotation transmission mechanism 6 includes a worm gear 5 connected to a worm wheel 7 whose rotational end position is regulated.
The worm wheel 7 is driven in forward and reverse rotation via the worm gear 5 and a pulley (intermediate rotating body) 8 coaxial with the worm gear 5. The pulley 8 and the worm gear 5 are connected to a common shaft 9. In contrast, it is attached with a loose fit.
On the opposing end surfaces of the pulley 8 and the worm gear 5, protruding engaging portions 10 and 11 are provided which abut against each other in the rotational direction.
0 and 11, the relative rotation amount (rotation angle θ) between the pulley 8 and the worm gear 5 is restricted to a range of 1/2 to 1 rotation (for example, 340 to 350 degrees) (see Figure 2). .

The rotational force of a motor 12 is transmitted to the pulley 8 via an endless belt 13. Further, the rotational force of the worm wheel 7 is transmitted to the large gear 15 via the small gear 14 integrated therewith. A fork member 16 having a bifurcated shape is integrally attached to the large gear 15.

On the other hand, an engaging pin 17 that slides along the horizontal guide groove 3 and the vertical guide groove 4 is protrudingly provided on the side surface of the cassette holder 2. It is held between the parts.

The same large gear 15 to which the horizontal guide groove 3, vertical guide groove 4 and fork member 16 are attached is also provided on the opposite side plate of the device body, and the large gears 15 on both sides are connected to each other. They are connected via a connecting shaft 18 so as to operate integrally.

Therefore, while the worm wheel 7 rotates by a certain angle (340 to 350 degrees), the fork member 16 that operates integrally with the worm wheel 7 slides the engagement pin 17 along the horizontal guide groove 3 and the vertical guide groove 4. The cassette holder 2 with the VTR cassette 19 inserted therein is moved from the cassette loading/unloading position shown in FIG. 1 to a predetermined loading position.

In the figure, 20 and 21 are upper and lower mounting plates fixed to the side plate 1 of the main body of the device, and each mounting plate 20 and 21 has a
Thrust bearings 22, 2 supporting both ends of the shaft 9
3 is installed.

The upper and lower mounting plates 20 of the thrust bearings 22 and 23,
21 is attached as shown in FIG.
Note that since the means for attaching the thrust bearing 22 to the upper mounting plate 20 and the means for attaching the thrust bearing 23 to the lower mounting plate 21 are the same, only the attachment of the upper thrust bearing 22 will be described.

The mounting plate 20 is provided with a circular hole 24 and a guide groove 25 that extends from the circular hole 24 to the edge of the mounting plate 20. Further, a protrusion 26 is provided on the outer surface of the mounting plate 20 at a position near the circular hole 24.
is installed protrudingly. The thrust bearing 22 includes a fitting part 27 that fits into the circular hole 24 of the mounting plate 20, and a pair of flange parts 28 provided on both sides of the mounting plate 20 so as to sandwich the peripheral edge of the circular hole 24. ,2
9, and one flange portion 28 has a mounting plate 2.
an extension 30 extending in one direction along the outer surface of 0;
is provided. Further, a bearing hole 31 that opens toward the other flange portion 29 is provided in the center of the thrust bearing 22, and the extension portion 30 is provided with a bearing hole 31 that opens toward the other flange portion 29.
6 is provided with a detent hole 32 that fits therein.
The fitting part 27 has two symmetrical sides parallel to each other
It has a notched shape at 3 and 33, and both parallel surfaces 3
3 and 33 is set to be slightly smaller than the width of the guide groove 25.

Therefore, the above-mentioned thrust bearing 22 is attached to the mounting plate 20.
In order to attach the fitting part 27 to the circular hole 24, first align the parallel surfaces 33, 33 of the fitting part 27 with the direction of the guide groove 25, and fit the fitting part 27 into the circular hole 24 through the guide groove 25. . After doing so, rotate the extension 30 approximately 90 degrees to align the detent hole 32 with the protrusion 26, and align the detent hole 32 with the protrusion 2.
6. This prevents the fitting portion 27 from coming out of the circular hole 24, and the attachment of the thrust bearing 22 to the mounting plate 20 is completed.

Furthermore, the worm gear 5 and pulley 8 can be attached to the shaft 9 by attaching the worm gear 5 and pulley 8 to the shaft 9 before attaching both the thrust bearings 22 and 23 to the upper and lower mounting plates 20 and 21.
Installation in this case is different from conventional press-fitting,
Since it is a loose fit, it is extremely easy to do.
Note that the endless belt 13 can also be attached by hanging it on the pulley 8 before attaching both thrust bearings 22 and 23 to the upper and lower mounting plates 20 and 21.

In the above configuration, when the VTR cassette 19 is inserted into the cassette holder 2 to a predetermined position,
A sensor (not shown) detects this and motor 1
2 is activated, the rotational force of the motor 12 is transmitted to the pulley 8 and the worm gear 5, and the worm wheel 7 meshed therewith is rotated at a reduced speed. The rotational force of the worm wheel 7 is transmitted to the fork member 16, and the fork member 16 first pulls the cassette holder 2 along the horizontal guide 3 to the deepest horizontal position, and then pulls the cassette holder 2 along the vertical guide 4 to a predetermined position. Move vertically downward to the cassette loading position.
Then, the position of the cassette holder 2 is detected by another sensor (not shown) and the power supply to the motor 12 is stopped.

At this time, the motor 12 cannot stop immediately even if the power is cut off, but rotates slightly due to inertia. This excessive rotation of the motor 12 is absorbed by slipping between the pulley 8 and the belt 13, but the helical teeth of the worm gear 5 become wedged into the teeth of the worm wheel 7.

Next, when taking out the cassette 19 (tape unloading operation), the motor 12 is rotated in the opposite direction to cause the cassette loading device to perform the opposite operation. At this time, the helical teeth of the worm gear 5 are biting into the teeth of the worm wheel 7, but when the pulley 8 rotates nearly one revolution due to the reverse rotation of the motor 12 and the inertia force increases, the engagement portion of the pulley 8 10 collides with the engaging portion 11 of the worm gear 5 in the rotational direction, and due to this collision, the phenomenon in which the helical teeth of the worm gear 5 bite into the teeth of the worm wheel 7 is easily released. After that, the rotational force of the motor 12 is transmitted through the pulley 8 to the worm gear 5, the worm wheel 7, the large gear 15,
It is transmitted to the cassette holder 2 via the fork member 16. In this way, when the cassette holder 2 returns to its initial position, the sensor detects this and stops the power supply to the motor 12.

At this time as well, the spiral teeth of the worm gear 5 will bite into the teeth of the worm wheel 7, as described above, but at the start of the next cassette loading operation, the pulley 8 has rotated nearly one revolution and the inertia force has increased. By the collision between the engaging portion 10 of the pulley 8 and the engaging portion 11 of the worm gear 5, the digging phenomenon can be easily released.

As described above, after the inertial force of the motor 12 becomes large, the engaging portion 10 of the pulley 8 engages the worm gear 5.
Since the worm gear 5 collides with the engaging portion 11 from the rotating direction, even if the helical teeth of the worm gear 5 bite into the teeth of the worm wheel 7, the biting is easily released when the motor 12 starts rotating in the opposite direction. It is.

For this reason, the design of the worm gear 5 and the worm wheel 7 becomes easy, and many effects such as cost reduction can be obtained.

Further, the attachment of the worm gear 5 and pulley 8 to the shaft 9 does not require a press-fitting process, and it is only necessary to fit the center holes of the worm gear 5 and pulley 8 to the shaft 9 by loose fitting, and furthermore, the both ends of the shaft 9 are The thrust bearings 22 and 23 are mounted on the mounting plate 2.
0 and 21, the assembly of the rotation transmission mechanism is completed.

Then, the shaft 9 of the worm gear 5 and the pulley 8
Since no press-fitting process is required for installation,
It is possible to facilitate assembly, reduce costs, and downsize.

Next, a second embodiment of the present invention shown in FIG. 4 will be described. Note that this embodiment is an example in which the thrust bearing is integrally formed with a portion of the upper and lower mounting plates.

That is, on the underside of the upper mounting plate 41, a long groove 42 of a predetermined length is formed from the edge of the mounting plate 41 toward the back by press working or the like.
Further, on the upper surface side of the lower mounting plate 43, at a position directly below the terminal position of the long groove 42, a bearing recess 44 is formed also by press working or the like.

The upper mounting plate 41 is, for example, screwed (screw 4) to an extension piece 45 that is a part of the VTR device main body.
6), stack the mounting plate 41 on the upper surface of the extension piece 45, and screw it in such a way that the portion of the long groove 42, excluding the terminal end, is covered by the extension piece 45. When stopped, both ends of the shaft 9 are supported by the terminal ends of the long grooves 42 and the bearing recesses 44. The upper end of the shaft 9 is prevented from slipping out of the long groove 42 by the extension piece 45.

In this configuration, the worm gear 5 and the pulley 8 are mounted on the shaft 9, an endless belt is also placed on the pulley 8, and the lower end of the shaft 9 is first fitted into the recess 44. After that, the upper end of the shaft 9 is fitted from the starting end side of the long groove 42 and moved to the terminal end, and in this state, when the upper mounting plate 41 is screwed to the extension piece 45, the rotation transmission mechanism is connected to the main body of the device. Installation is complete.

Also in the above embodiment, the same effects as in the first embodiment can be obtained.

Note that the present invention is not limited to the first and second embodiments described above, and can be modified in various ways. For example, in claims 1 and 2, only one of the intermediate rotating body (pulley 8 in the embodiment) or the worm gear may be made to prevent loosening from the shaft, and the other may be press-fitted.

Further, in any of claims 1 to 4, a gear may be used as the intermediate rotating body, but in this case, a friction transmission mechanism for absorbing the excessive rotation amount of the motor is provided between the motor and the intermediate rotating body. It is good to intervene.

[Effect] As described above, the invention of claims 1 and 2 makes both or one of the intermediate rotating body and the worm gear rotatable about a common axis, and the intermediate rotating body and the worm gear are provided with rotational directions that are different from each other. An engaging portion is provided that makes close contact with each other and limits the amount of relative rotation between the intermediate rotating body and the worm gear to a range of 1/2 to 1 rotation. This allows for an extremely simple configuration without increasing the starting force of the drive source.
It is possible to release the spiral teeth from biting into the worm wheel.

Further, in the invention of claims 3 and 4, both the intermediate rotating body and the worm gear are loosely fitted to the shaft, and both ends of the shaft are supported by thrust bearings, and the intermediate rotating body and the worm gear are engaged with each other. The rotation of the intermediate rotating body is transmitted to the worm gear by engaging in the rotational direction at the joint. This makes it extremely easy to attach the worm gear and intermediate rotating body to the shaft, and there is no need for a high degree of dimensional accuracy in the hole diameter of the intermediate rotating body and worm gear or the outer diameter of the shaft, unlike in conventional mechanisms. Therefore, it is possible to reduce component costs. Moreover, by omitting the press-fitting process, there is no need to set the strength of the shaft unnecessarily high, which also reduces costs.
It is also possible to reduce the size.

[Brief explanation of drawings]

Figures 1 to 3 show the first embodiment. Figure 1 is a schematic side view of the tape loading device as seen from the side of the VTR mechanism, and Figure 2 is taken along the - line in Figure 1. 3 is a partially cutaway plan view showing the thrust bearing installation process, and 4 is a cross-sectional view.
The figure is a perspective view showing the installation process of the thrust bearing in the second embodiment, and FIG. 5 is a longitudinal sectional view showing the conventional example. 5...Worm gear, 7...Worm wheel, 8...Pulley (intermediate rotating body), 9...Shaft, 1
0... Engaging portion of intermediate rotating body 8, 11... Engaging portion of worm gear, 22, 23... Thrust bearing.

Claims (1)

[Claims for Utility Model Registration] (1) The worm gear 5 is meshed with the worm wheel 7 whose rotational end position is regulated, and the rotational force of the drive source is transmitted to the worm gear 5 to rotate the worm wheel 7 in the forward and reverse directions. In the rotation transmission mechanism for rotational driving, an intermediate rotary body 8 to which the rotational force of the drive source is frictionally transmitted is provided coaxially with the worm gear 5, and at least one of the intermediate rotary body 8 and the worm gear 5 is connected to a common rotor. It is rotatable about the shaft 9, and contacts each of the intermediate rotating body 8 and the worm gear 5 in the rotational direction, so that the amount of relative rotation between the intermediate rotating body 8 and the worm gear 5 is in the range of 1/2 to 1 rotation. an engaging portion 10 that regulates
1. A rotation transmission mechanism including a worm gear. (2) The engaging portions 10 and 11 are connected to the intermediate rotating body 8.
A rotation transmission mechanism including a worm gear according to claim 1, wherein the worm gear is a protrusion protruding from each opposing end surface of the worm gear. (3) A rotation transmission mechanism in which a worm gear 5 is meshed with a worm wheel 7 whose end position of rotational movement is regulated, and the rotational force of a drive source is transmitted to the worm gear 5 to drive the worm wheel 7 in forward and reverse rotation, Both thrust bearings 22 of one shaft 9 whose both ends are supported by thrust bearings 22 and 23,
The intermediate rotating body 8 and the worm gear 5, to which the rotational force of the drive source is transmitted by friction, are loosely fitted between the intermediate rotating body 8 and the worm gear 5, respectively, between the intermediate rotating body 8 and the worm gear 5, and the intermediate rotating body 8 and the worm gear 5 are provided with A rotation transmission mechanism including a worm gear, characterized in that engaging portions 10 and 11 are provided which are engageable and detachable and engage with each other in the rotational direction. (4) The rotation transmission mechanism including a worm gear according to claim 3, wherein the engaging portions 10 and 11 are protrusions protruding from opposing end surfaces of the intermediate rotating body 8 and the worm gear 5.