JPH0625043Y2 - Overload prevention clutch for electric telescopic antenna - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to an overload prevention clutch provided in a rotary transmission system of an electric expansion / contraction antenna that expands / contracts an antenna element by driving a motor, and particularly to an overload prevention clutch for an electric expansion / contraction antenna suitable for passenger cars because of quiet operation noise.

[Prior art]

As an overload prevention clutch for the above-mentioned electric telescopic antenna, a driving side clutch plate and a driven side clutch plate, which are pressed against each other by a spring bias, are provided. When the driven side clutch plate engages with the engaging recess, both sides engage in slopes in both forward and reverse rotation directions to transmit torque, and when overloaded, the two slide on the front side in the rotation direction. When the drive side clutch plate rotates from the clutch disengaged state by rotating relative to each other while being separated from each other by the spring urging force, both of them are urged by the spring to cause the slope engaging portion on the rear side in the rotation direction. Conventionally, there is known one configured to return to a clutch connection state by being fitted with sliding.

[Problems to be solved by the device]

The overload prevention clutch as described above has the advantages that the transmission torque is high and that the torque value that is interrupted at the time of overload is easy to set. However, in order to secure sufficient transmission torque and high wear resistance, the pair of clutch plates is usually made of a combination of hard resins or a combination of resin and metal, and in that relationship,
When the clutch plates are separated from each other and the clutch plates are pressed against each other by the spring bias to return to the clutch state, an offensive striking sound is generated. For this reason, the above-described conventional overload preventing clutch has a problem in being incorporated in an electric telescopic antenna equipped in a passenger car that requires high quietness. In view of this, the present invention is based on the slope engagement by the concavo-convex fitting that has a high transmission torque and that can easily set the torque value that shuts off when an overload occurs. It is an object of the present invention to provide an overload prevention clutch for an electric telescopic antenna, which is highly silent and capable of sufficiently reducing the impact sound of. In order to reduce the impact noise between the clutch plates when the clutch is engaged, there is the prior art disclosed in Japanese Utility Model Publication No. 57-26405 proposed by the applicant of the present application.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides an overload preventing clutch constructed as described above, wherein the engaging projections of the drive side clutch plate are for transmitting torque to both front and rear ends facing in the forward and reverse rotation directions. A fixed convex portion corresponding to the engagement concave portion having a relatively steep contact slope, and a relatively loose contact inclined surface for cushioning at both front and rear end portions facing in the forward and reverse rotation directions, and with respect to the fixed convex portion They are arranged in parallel so that they can move relative to each other in the forward and reverse rotation directions by a predetermined amount, and when the clutch is disengaged, they are moved rearward in the rotational direction from the fixed convex portion by contact with the driven side clutch plate, and the inclined surface engaging portion on the rear side in the rotational direction. The structure is combined with the moving convex portion that constitutes the above.

[Action]

In the present invention employing such means, the fixed convex portion of the drive side clutch plate and the engagement concave portion of the driven side clutch plate are relatively sharp for torque transmission in both forward and reverse rotation directions of the drive side clutch plate. The predetermined torque is transmitted from the drive side clutch plate to the driven side clutch plate by engaging the slopes via the contact slopes. Then, at the time of overload when the transmission torque becomes a predetermined value or more,
The sloped engaging portion between the fixed convex portion and the engaging concave portion slides so that the drive side clutch plate moves together with the fixed convex portion and the moving convex portion relative to the driven side clutch plate against the spring bias and relatively rotates. The torque transmission is thus cut off. When the drive side clutch plate rotates normally or reversely from this clutch disengaged state, the moving convex portion moves relative to the fixed convex portion rearward in the rotational direction by a predetermined amount due to contact with the driven side clutch plate, and the buffering thereof is performed. The relatively slant contact slope for use constitutes the slope engagement portion on the rear side in the rotation direction of the drive side clutch plate. Then, the driving side clutch plate gently approaches the driven side clutch plate due to the spring bias with the sliding of the slope engaging portion composed of the relatively gentle contact slope for buffering, and the fixed convex portion and the moving concave portion are driven. By engaging with the engaging convex portion of the side clutch plate, the clutch connection state is restored.

【Example】

An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 2 shows an outline of the entire structure of an electric telescopic antenna of one embodiment applied to an automobile. In the drawing, reference numeral 1 is a drive unit having a built-in rotary transmission system including an overload prevention clutch described later. A lower end of an antenna sliding cylinder 5 that slidably accommodates a motor 3 as a drive source and an antenna element 4 is fixed to the housing 2. And such an electric telescopic antenna can be used for the bracket 6,
It is fixed in place on the body of the car through 7,
The upper end of the antenna sliding cylinder 5 is the fender panel 8 of the automobile.
The antenna element 4 can be extended on the fender panel 8 by being attached by penetrating. Next, the internal structure of the drive unit 1 will be described with reference to FIG.
A fixed central shaft 9 also serving as a tightening bolt for the housing 2 traverses in the housing 2, and a worm wheel 11 meshing with a worm 10 mounted on the rotary shaft of the motor 3 is provided therewith.
A pipe shaft 13 integrally formed with the worm wheel 11 and having a spline 12 on the outer periphery is rotatably fitted. A clutch plate 14 on the drive side is spline-fitted to the outer periphery of the tube shaft 13, and a clutch plate 15 on the driven side is rotatably fitted adjacent to the worm wheel 11. A spring bearing 17 is attached to the tube shaft 13 by an E-ring 16 so as not to come off, and a spring 18 interposed between the spring bearing 17 and the driving side clutch plate 14 causes the driving side clutch plate 14 to move. Is pressed against the driven clutch plate 15, and these constitute an overload prevention clutch. On the other hand, the driven clutch plate 15 is integrally formed with a drive gear 21 that meshes with the latch teeth 20 of the drive cord 19 connected to the antenna element 4. Now, the clutch plates 14 and 15 will be described. The driving side clutch plate 14 is made of a hard resin, and an engaging convex portion 22 is provided at one position in the circumferential direction on the clutch face facing the driven side clutch plate 15 (third part).
See figure). The engagement protrusion 22 is a ring groove 23 of the clutch plate 14.
Slide ring 24 that fits (see FIGS. 4 and 5)
Of the ring groove 2 and the fixed convex portion 26 integrally formed on the clutch plate 14 adjacent to the outer peripheral side of the moving convex portion 25.
3 By the engagement of the rotation stopper 27 at the bottom and the positioning recess 28 (see FIG. 6 to FIG. 8) of the slide ring 24, the moving convex portion 25 moves forward and backward relative to the fixed convex portion 26 in the rotational direction of the clutch plate 14. It is possible to move relative to a predetermined amount. The fixed convex portions 26 have contact slopes 29, which are relatively steep slopes (see FIG. 9), at both front and rear ends in the rotation direction of the clutch plate 14.
On the other hand, the contact slope 30 on the side of the moving convex portion 25 has a relatively gentle slope as shown in FIG. 10, and in the state where the moving convex portion 25 moves relative to the fixed convex portion 26, The engaging convex portion 22 that is a combination of these has a contact slope 29 for transmitting torque that is steep at one end and a contact slope 30 for buffering that is gentle at the other end (see FIG. 11). It should be noted that ridge line portions 32 are formed on both sides of the shallow concave portion 31 on the upper surface of the moving convex portion 25, and the ridge line portions 32 slightly project from the upper surface of the fixed convex portion 26. The driven side clutch plate 15 is made of a molded product of hard resin as shown in FIGS. 12 and 13, and its clutch face has an engagement recess 33 into which the engagement projection 22 is fitted. , 34 are formed at two positions separated by a half rotation in the rotation direction of the clutch plate 15. These engaging recesses 33, 34
The contact slopes 35 and 36 with the engaging convex portion 22 in
Both are steep slopes corresponding to the contact slopes 29 of the fixed convex portion 26. Further, the two fan-shaped base portions 3 that partition the engagement recesses 33 and 34
Protrusions 39 that can be fitted into the shallow concave portions 31 of the moving convex portions 25 are formed on the inner peripheral sides of the upper surfaces of the reference numerals 7 and 38 near the contact slopes 35 and 36. In FIG. 1, reference numeral 40 is a switch plate rotatably supported on the inner surface of the housing 2, and a tooth portion 42 meshing with a feed dog 41 protruding from the outer end surface of the worm wheel 11 is provided on the outer periphery thereof. Has been formed. The switch plate 40 is attached to the 1 of the warm wheel 11.
Upon rotation, one tooth is intermittently rotated to turn off the power source of the motor 3 at the extension limit and contraction limit of the antenna element 4. In the electric telescopic antenna having the above configuration, the forward and reverse rotations of the motor 3 are decelerated by the engagement between the worm 10 and the worm wheel 11, and are transmitted from the tube shaft 13 to the clutch plate 14. Here, when the engagement protrusion 22 of the clutch plate 14 meshes with one engagement recess 33 of the clutch plate 15, the contact slope 29 of the fixed protrusion 26 and the contact slope 35 of the engagement recess 33.
Sufficient drive torque is transmitted to the clutch plate 15 by contact with the clutch plate 15. Then, the clutch plate 15 is driven by this driving torque.
At the same time, the drive gear 21 is rotated so that the drive cord 19 is pushed or pulled in the longitudinal direction thereof, and the antenna element 4 is expanded or contracted. When the antenna element 4 reaches the extension / contraction limit, the switch plate 4
Although the power of the motor 3 is turned off by the rotation of 0, the tube shaft 13 is slightly rotated by the inertia of the motor 3 and the worm wheel 11. At this time, resistance is applied to the transmission system after the clutch plate 15, so that in the clutch plate 14, the contact slope 29 of the fixed protrusion 26 in the engagement protrusion 22 of the clutch plate 15 is the contact slope 35 of the engagement recess 33 of the clutch plate 15. Guided by, it rotates while moving in the direction of the tube axis 13 against the spring 18. The rotation of the clutch plate 14 is performed quietly with little resistance in a one-sided tilted state with respect to the clutch plate 15, and thus transmission of an overload to the antenna element 4 side is prevented. When the clutch plates 14 and 15 are disengaged due to the expansion and contraction limit of the antenna element 4, the shallow recess 31 in the moving projection 25 on the clutch plate 14 side is the fan-shaped base 3 on the clutch plate 15 side.
It is fitted to the protrusion 39 of No. 7. Therefore, when the motor 3 is rotated in the reverse direction from this state, the fixed convex portion 26 together with the clutch plate 14
And the engaging protrusion 22 has a steep contact slope 29 for torque transmission on the front side and a gentle contact slope 30 for buffering on the rear side in the reverse direction. Become. In this form, the moving convex portion 25 is replaced by the fixed convex portion 26.
At the same time, the reverse rotation is started, and eventually the engaging convex portion 22 is fitted into the engaging concave portion 33 of the clutch plate 15 by the urging force of the spring 18 to connect the clutch. At this time, the clutch plate 14 is guided by the contact slope 30 of the moving projection 25, which has a gentle inclination, for contact with the vicinity of the protrusion 39 of the base 37 of the clutch plate 15, so that the clutch plates 14 and 15 are uneven. Connection by fitting is done gently.

[Effect of device]

As described above, in the present invention, the fixed convex portion of the driving side clutch plate and the engaging concave portion of the driven side clutch plate are relatively steep contact slopes for torque transmission in both the forward and reverse rotation directions of the driving side clutch plate. A predetermined torque is transmitted from the driving side clutch plate to the driven side clutch plate by engaging the inclined surface via the. Then, at the time of an overload in which the transmission torque becomes a predetermined value or more, the slope engagement portion between the fixed convex portion and the engaging concave portion slides, and the driving side clutch plate moves with respect to the driven side clutch plate together with the fixed convex portion and the moving convex portion. It relatively rotates while being separated from the spring bias, and thus the torque transmission is interrupted. When the drive side clutch plate rotates normally or reversely from this clutch disengaged state, the moving convex portion moves relative to the fixed convex portion rearward in the rotational direction by a predetermined amount due to contact with the driven side clutch plate, and the buffering thereof is performed. The relatively slant contact slope for use constitutes the slope engagement portion on the rear side in the rotation direction of the drive side clutch plate. Then, the driving side clutch plate gently approaches the driven side clutch plate by the spring bias with the sliding of the slope engaging portion composed of the relatively gentle contact slope for buffering, and the fixed convex portion and the moving convex portion are By engaging with the engagement recess of the driven side clutch plate, the clutch connection state is restored. Therefore, according to the present invention, the transmission torque in the clutch connected state is high and the breaking torque value at the time of overload can be easily set. It is possible to sufficiently reduce the hitting sound and ensure high quietness.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a drive unit of an electric telescopic antenna showing an embodiment of the present invention, FIG. 2 is a schematic view of the entire structure, FIG. 3 is a perspective view of a drive side clutch plate, and FIG. 4 is a drive side. Front view of the clutch plate, FIG. 5 is a half sectional view of the same, FIG. 6 is a front view of the slide ring, FIG. 7 is a side view of the same, FIG. 8 is a rear view of the same, and FIG.
FIG. 10 is a sectional view of the contact slope of the fixed protrusion, FIG. 10 is a sectional view of the contact slope of the moving protrusion, and FIG. 11 is a contour line diagram of the engaging protrusion.
FIG. 12 is a front view of the driven side clutch plate, and FIG. 13 is a half sectional view of the same. DESCRIPTION OF SYMBOLS 1 ... Drive part, 2 ... Housing, 3 ... Motor, 4 ... Antenna element, 5 ... Antenna sliding cylinder, 6,7 ... Bracket, 8 ... Fender panel, 9 ... Fixed central axis, 10 ... Worm, 11 ... Worm wheel , 12 ... Spline, 13 ... Pipe shaft, 14 ... Drive side clutch plate, 15 ... Driven side clutch plate, 16 ... E ring, 17 ... Spring receiver, 18 ... Spring, 19 ... Drive cord, 20 ... Rack tooth, 21 ... Drive gear, 22 ... convex part, 23 ... ring groove, 24 ... slide ring, 25 ... moving convex part, 26 ... fixed convex part, 27 ... rotation stop, 28 ... positioning concave part, 29 ... contact slope, 30 ... contact slope, 31 ... Shallow recess, 32 ... Ridge line part, 33, 34 ... Engagement recess, 35, 36 ... Contact slope, 37, 38 ... Fan base part, 39 ... Projection, 40 ... Switch plate, 41 ... Feed dog, 42 … Tooth.

Claims (1)

[Scope of utility model registration request] 1. An overload prevention clutch provided in a rotary drive system of an electric telescopic antenna for expanding and contracting an antenna element by driving a motor, wherein a drive side clutch plate and a driven side are pressed against each other by spring bias. With the clutch plate, when the clutch is engaged, the engaging convex portion of the drive side clutch plate and the engaging concave portion of the driven side clutch plate are fitted to each other so that the both are inclined to engage in the forward or reverse rotational direction. When torque is transmitted, and when the load is overloaded, both of them slide relative to each other against the spring bias by the sliding of the slope engaging portion on the front side in the rotation direction, and they rotate relative to each other, causing a clutch disengagement state. In the overload prevention clutch configured to return to the clutch connected state by rotating the two, the both are fitted by the spring bias with the sliding of the slope engaging portion on the rear side in the rotating direction, and The engaging convex part of the moving side clutch plate has a fixed convex part corresponding to the engaging concave part having relatively steep contact slopes for torque transmission at both front and rear ends facing in the forward and reverse rotation directions, and a forward and reverse rotation. Have relatively loose contact slopes at the front and rear ends facing each other in the direction, and are arranged in parallel so as to be movable relative to the fixed convex portion in the forward and reverse rotation directions by a predetermined amount, and are in the clutch disengaged state on the driven side. An overload of an electric telescopic antenna, characterized in that the structure is combined with a moving convex portion that moves rearward in the rotational direction from the fixed convex portion by contact with the clutch plate to form a slope engaging portion on the rear side in the rotational direction. Prevention clutch.