JPH0619185B2 - Clutch mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch mechanism capable of selectively switching a power transmission path in a video tape recorder (hereinafter referred to as VTR) or the like.

2. Description of the Related Art In recent years, a magnetic tape device such as a VTR often uses a mechanism for selectively transmitting the power of a driving source to a driven body.

An example of a conventional clutch mechanism will be described below with reference to the drawings. FIG. 7 and FIG. 8 are cross-sectional views of a main part of a conventional clutch mechanism. In FIG. 7, a driving gear 3 rotatably supported on a shaft 2 planted on a substrate 1 is rotationally driven by a motor (not shown). The clutch gear 4 that is always meshed with the driving gear 3 is
It is rotatably supported by a shaft 5 embedded in the substrate 1 and movable in the direction of the shaft 5, and is biased by a compression spring 6 in a direction toward the substrate 1. Further, the clutch gear 4 has a first surface 7a and a second surface 7b having different heights, and
It is mounted on a sliding clutch plate 7 guided above by a shaft 5 and meshes with a driven gear 8. The driven gear 8 is rotatably supported by a shaft 9 planted in the substrate 1.

Regarding the conventional clutch mechanism configured as described above,
The operation will be described below.

In the state of FIG. 7, the rotational force of the motor (not shown) is transmitted to the driven gear 8 via the driving gear 3. Here, when the clutch plate 7 moves leftward from the position shown in FIG. 7 and reaches the position shown in FIG. 8, the clutch gear 4 moves from the first surface 7a to the second position by the biasing force of the compression spring 6. The shaft 5 is guided and moved onto the surface 7b, and the mesh with the driven gear 8 is released.

On the contrary, if the clutch plate 7 is moved rightward from the state shown in FIG. 8, the clutch gear 4 is pushed up in the direction of the shaft 5 against the urging force of the compression spring 6 and meshes with the driven gear 8. become.

Problems to be Solved by the Invention However, in the above-mentioned configuration, when the clutch gear 4 moves from the position of FIG. 7 to the position of FIG. 8 by the urging force of the compression spring 6, the load applied to the driven gear 8 is increased. Is large, the transmission load at each contact point between the tooth flank of the driven gear 8 and the tooth flank of the clutch gear 4 and the tooth flank of the clutch gear 4 and the tooth flank of the driving gear 3 becomes large. The frictional force between the tooth flanks that hinders the movement in the direction of the axis 5 also becomes large, and the clutch gear 4 cannot move due to the balance between the urging force of the compression spring 6 and the frictional force, so that a reliable switching operation can be performed. I couldn't do it.

Although it is possible to increase the biasing force of the compression spring 6, the load of the clutch spring 4 is always applied when the driven gear 8 is rotating, so the load is increased by the biasing force of the compression spring 6. Then, the power consumption of the motor (not shown) may increase, and uneven rotation may occur.

In view of the above-mentioned problems, the present invention provides a clutch mechanism having a simple structure and a reliable switching operation.

Means for Solving the Problems In order to solve the problems, the clutch mechanism of the present invention is
A driving wheel, an engaging member that moves in the radial direction of the driving wheel to engage and disengage with the driving wheel, and a first biasing force that biases the engaging member in the direction of engaging the driving wheel. Means, a driven wheel that respectively supports the engagement member and the first biasing means, and that integrally rotates coaxially with the driving wheel when engaged with the engagement member; The separating member that moves between a non-contacting position that does not contact the engaging member and a contacting position that can contact the engaging member, and the direction of urging the separating member by the first urging means. Second urging means for urging in the opposite direction and contacting the driven member with the separating member so that the separating member is urged by the second urging means. Is provided with a first contact portion for moving in the opposite direction, and the release member is in contact with the first contact portion. A second contact portion for moving the separating member in a direction opposite to the urging direction of the second urging means, and contact between the first contact portion and the second contact portion. After moving to the direction opposite to the urging direction by the second urging means, the pressing portion presses the engaging member in the urging direction by the second urging means to separate it from the driving wheel. And abutting against the engaging member at the abutting position locks the movement of the separating member in a direction opposite to the urging direction of the second urging means at a predetermined position. In order to release the engagement relationship between the engaging member and the driving wheel, the pressing portion moves the engaging member against the urging force of the first urging means at the predetermined position. And a locking means.

The present invention has the above-described structure, and by engaging and disengaging the engaging member interposed between the driving wheel and the driven wheel, the transmission / non-transmission of the power from the driving wheel to the driven wheel is surely selected. be able to.

Embodiment A clutch mechanism according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a cross-sectional view of the relevant part, and FIGS.
The figure is a plan view of the same.

In this embodiment, the driving wheel is the driving gear 12, the engaging member is the clutch member 13, the first biasing means is the spring 15, and the driven wheels are the driven gears 14 in the claims.
The releasing member is the releasing member 19, and the second urging means is the compression spring 2.
0, the first contact portion is the cam surface 14c, and the second contact portion is the first
The contact portion 19c, the pressing portion corresponds to the second contact portion 19d, and the locking means corresponds to the shaft 17 and the locking surface 19d.

In the drawing, a driving gear 12 is constantly driven by a motor (not shown) on a shaft 11 implanted in a substrate 10.
Is rotatably supported, and the projection 12 is provided on the inner periphery thereof.
a is provided at a predetermined interval. Also, a boss portion 14a that engages with a guide groove 13b provided in the clutch member 13 having a first convex portion 13a that has an engaging relationship with the protrusion portion 12a and guides the clutch member 13 slidably, and a clutch. A driven gear 14 having a member 13 and a groove 14b to be fitted therein is rotatably supported on the shaft 11. Further, by the spring 15 stretched on the driven gear 14,
The clutch member 13 is biased rightward in FIG.
It engages with a protrusion 12 a provided on the driving gear 12. Therefore, the rotational force of the driving gear 12 is transmitted to the driven gear 14 via the clutch member 13. If the clutch member 13 moves to the left in FIG. 2 against the urging force of the spring 15, the engagement between the first convex portion 13a and the protruding portion 12a is released, and the driving gear 12 of the driving gear 12 is released. The rotational force is configured not to be transmitted to the driven gear 14. Further, the clutch member 13 has a second convex portion 13c that comes into contact with a release member described later. A cam having an opening 14d on the outer peripheral portion of the driven gear 14 that is narrow in the vicinity of the second convex portion 13c of the clutch member 13 and sandwiches the second convex portion 13c in the biasing direction of the clutch member 13 at both sides. The surface 14c is provided, and the cam member 1 is moved to the right side in FIG.
The contact relationship between 4c and the disengagement member is released, and the disengagement member can press the second convex portion 13c of the clutch member 13. The support plate 16 is formed by a known means (for example,
Driven by solenoid to drive the substrate 1
0 is reciprocated between the non-operating position shown in FIG. 1 and the operating position shown in FIG. 3, and is locked at the operating positions shown in FIGS. 1 and 3. Shafts 17 and 18 are planted in the support plate 16, and the release member 1
The guide member 19 engages with the guide groove 19a to support the separating member 19 slidably in the left-right direction in FIG. Also, the detaching member 19
Is subjected to an urging force to the left in FIG. 1 by the compression spring 20 fitted between the support plate 16 and
It comes into contact with the end of 9a, and the releasing member 19 is locked at the position shown in FIG. When the detaching member 19 is moved rightward in FIG. 3 against the biasing force of the compression spring 20, the engaging surface 19b contacts the shaft 17 and is engaged at the position shown in FIG. Is done. Further, the end of the separating member 19 is brought into contact with the cam surface 14c and the separating member 19 is moved to the third position.
A first contact portion 19c having a wide shape toward the urging direction of the separating member 19 for moving to the right in the figure,
A second contact portion 19d that can contact the second convex portion 13c is provided.

Next, the operation will be described.

FIG. 1 shows the state where the support plate 16 is locked in the non-operating position, and the cam surface 14c and the first contact portion 19c are in a positional relationship where they do not contact each other. Therefore, the clutch member 13 is biased by the spring 15 in the diagonally upper right direction in FIG. 1, and the first convex portion 13a and the protrusion 12a provided on the driving gear 12 are engaged with each other. For example, if the driving gear 12 is rotationally driven in the clockwise direction by a motor (not shown) in FIG. 1, the clutch member 13 having the first convex portion 13a engaged with the protrusion 12a. Is also rotated clockwise. Therefore, the rotational force of the motor (not shown) is also transmitted to the driven gear 14 and the driven gear 14
Rotates clockwise.

Next, the operation of making the rotational force of the driving gear 12 non-transmitted to the driven gear 14 will be described. The support plate 16 is moved from the non-operating position shown in FIG. 1 to the operating position shown in FIG. 3 by known means, and is locked at this operating position. As a result, the first contact portion 19c of the detaching member 19 on the support plate 16 and the cam surface 14c of the driven gear 14 are brought into contact with each other. From the state shown in FIG.
Is rotated clockwise, the cam surface 1c and the first contact portion 1
9c abuts each other, and the separating member 19 is once moved rightward against the biasing force of the compression spring 20. Further, the driving gear 12
When is rotated clockwise, the first contact portion 19c approaches the opening 14d as shown in FIG. 4, so that the second contact portion 19d and the second convex portion 13c can contact each other. Become. At this time, the load torque T is applied to the driven gear 14. Therefore, from the center of the shaft 11, the protrusion 12a of the driving gear 12 and the first protrusion 13a of the clutch member 13 are formed.
If the distance to the contact point with and is R and the tangential force at the contact point is N, then N = T / R (1) Further, if the friction coefficient at the contact point is μ and the frictional force acting between the clutch member 13 and the groove 14b is f ′, the frictional force f in the sliding direction of the clutch member 13 on the driven gear 14 is f = μ × N + f ′ = μ × T / R + f ′ (2) Therefore, if the disengagement force F for moving the clutch member 13 in the direction of disengagement from the driving gear 12 in the state shown in FIG. 4 is P, which is the biasing force of the spring 15 in the engagement direction of the clutch member 13, F = f + P (3) is required. By the way, since the urging force of the compression spring 20 urging the separating member 19 to the left in FIG. 4 is set to be smaller than the separating force F and larger than the urging force P of the spring 15, The second convex portion 13c is the second contact portion 1
When it comes into contact with 9d, the releasing member 19 moves to the right in FIG. 4, but its movement is restricted by the shaft 17 and the locking surface 19b. Therefore, when the driving gear 12 further rotates in the clockwise direction in FIG. 4, the clutch member 13 moves to the second position.
Of the contact portion 19d moves to the left along the slope of the contact portion 19d, the protrusion 12a and the first convex portion 13a are disengaged as shown in FIG. 5, and the rotational force of the driving gear 12 is driven. It is not transmitted to the gear 14. Protrusion 12a and first convex portion 13a
After being disengaged from the driving gear 12, the clutch member 13 is further moved leftward to the position shown in FIG. 6 against the urging force of the spring 15 by the urging force of the compression spring 20.
Projection 12 a of the clutch member 13 and the first protrusion 13 of the clutch member 13.
Completely pull apart a.

Further, when the load T varies and becomes smaller than the set value, for example, the clutch member 13 can be moved in the disengagement direction only by the urging force of the compression spring 20,
Even when the load T increases, the rightward movement of the disengagement member 19 is restricted by the shaft 17 and the locking surface 19b, so that the clutch member 13 can be reliably moved in the disengagement direction. In this way, highly reliable operation can be obtained even if the load T varies.

Here, the urging force of the compression spring 20 acts on the driven gear 14 only while the driven gear 14 and the disengaging member 19 make contact with each other and shifts to the non-transmitted state, and in the steady state of rotation transmission, It has no influence on the rotation of the driving gear 12 and the driven gear 14.

On the other hand, the first contact portion 19c of the detaching member 19 is fitted into the openings 14d of the two cam surfaces 14c, and the driven gear 1
The clockwise and counterclockwise rotations of 4 are restricted.
Therefore, even if vibration or the like is applied from the outside, the clutch member 13 and the driving gear 12 do not accidentally engage with each other,
Further, since the driven gear 14 does not rotate much, a reliable disengagement operation can be performed.

Further, since the shapes of the opening 14d and the first contact portion 19c are as shown in the figure, the first contact portion 19c has the opening 1
Immediately falls to 4d, and a sharp disengagement operation is obtained.

As described above, since the first contact portion 19c that contacts the cam surface 14c and the second contact portion 19d that presses the second convex portion 13c are respectively provided, the shape suitable for the operation is obtained. Can be set arbitrarily and countermeasures against wear and the like can be taken respectively, so that a more reliable clutch mechanism can be obtained.

Next, from the state of non-transmission of the rotational force shown in FIG.
When 6 is moved to the position shown in FIG. 1 by a well-known means, the clutch member 13 moves to the right in FIG. 6 by the urging force of the spring 15 with the movement of the contact member 19 to move to the first position.
Of the drive gear 1
The rotational force of 2 drives the driven gear 14 via the clutch member 13.
Will be transmitted to.

In the above description, the case where the driving gear 12 rotates in the clockwise direction has been described, but the configuration is such that the same operation and effect can be obtained even in the case of the counterclockwise rotation.

Further, before the clutch member 13 and the disengagement member 19 are brought into contact with each other, the cam surface 14c is provided as an abutting portion for moving the disengagement member 19 to the right, but the shape is not limited to that shown in the drawing. , Pins, etc. may be planted.

Further, although the protrusion 12a is provided on the inner peripheral side of the driving gear 12, the shape is not limited to the illustrated shape, and a gear or a pin may be planted.

EFFECTS OF THE INVENTION As described above, the present invention includes a driving wheel, and an engaging member that moves in the radial direction of the driving wheel to engage and disengage with the driving wheel.
A first urging means for urging the engaging member in a direction in which it engages with the same wheel for the previous period, and the engaging member and the first urging means are respectively supported, and the engaging member Between the driven wheel that integrally rotates coaxially with the driving wheel when engaged, the non-contact position that does not contact the engagement member, and the contact position that can contact the engagement member. The driven wheel comprises: a moving separating member; and a second urging member that urges the separating member in a direction opposite to the urging direction of the first urging member. A first contact portion that moves the separating member in a direction opposite to the urging direction of the second urging means by contacting the separating member is provided, and the separating member includes the first contact portion. A second abutting member that abuts the abutting portion and moves the separating member in a direction opposite to the urging direction of the second urging means. Parts and, with the first contact portion and the second
Abutting against the abutting portion of the second biasing means to move in a direction opposite to the biasing direction of the second biasing means, and then press the engaging member in the biasing direction of the second biasing means. And a second pressing portion that separates from the driving wheel, and the second member of the separating member contacts the engaging member at the contact position.
The movement in the direction opposite to the urging direction of the urging means is locked at a predetermined position, and the pressing portion resists the urging force of the first urging means at the predetermined position. By providing the locking member for moving the coupling member and releasing the engagement relationship between the engagement member and the driving wheel, even if the load varies and becomes larger than the set value, As the movement of the second urging means in the direction opposite to the urging direction is restricted by the locking means, the engaging member can be reliably moved in the disengagement direction. In this way, even if the load varies, the engagement member interposed between the driving wheel and the driven wheel is engaged and disengaged to ensure the transmission / non-transmission of power from the driving wheel to the driven wheel, and It is possible to obtain a very excellent effect of selecting with high reliability.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a clutch mechanism according to an embodiment of the present invention, FIG. 2 is a sectional view of the same, FIG. 3, FIG. 4, FIG.
FIG. 6 is a plan view of the same embodiment, and FIGS. 7 and 8 are sectional views of a main part of a conventional clutch mechanism. 12 ... Driving gear, 13 ... Clutch member, 14 ... Driven gear, 14c ... Cam surface, 15 ... Spring, 17 ...
Shaft, 19 ... Releasing member, 19b ... Locking surface, 19c ...
1st contact part, 19d ... 2nd contact part, 20 ... Compression spring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-141317 (JP, A) JP 62-200028 (JP, A) JP 50-5600 (JP, B1)

Claims (3)

[Claims] 1. A driving wheel, an engaging member that moves in a radial direction of the driving wheel to engage and disengage with the driving wheel, and urges the engaging member in a direction to engage the driving wheel. A first urging means, the engaging member and the first urging means are respectively supported, and when engaged with the engaging member, they rotate integrally with the driving wheel coaxially. A driven wheel, a disengagement member that moves between a non-contact position that does not contact the engagement member and a contact position that can contact the engagement member, and the disengagement member that acts as the first urging means. And a second urging means for urging in a direction opposite to the urging direction of the driven member by the second biasing means. A first contact portion for moving in a direction opposite to the urging direction of the urging means is provided, and the separating member is provided with the first contact portion. A second abutting portion that abuts against a portion and moves the detaching member in a direction opposite to the urging direction of the second urging means; the first abutting portion and the second abutting portion. After moving to the direction opposite to the urging direction of the second urging means by contact with the portion, the engaging member is pressed in the urging direction of the second urging means to move from the driving wheel. By providing a pressing portion for disengagement and contacting the engaging member at the contact position, the disengagement member is moved at a predetermined position in a direction opposite to the urging direction of the second urging means. And the pressing portion moves the engagement member against the urging force of the first urging means at the predetermined position, and the engagement relationship between the engagement member and the driving wheel is retained. A clutch mechanism provided with locking means for releasing. 2. The clutch mechanism according to claim 1, wherein the urging force of the engagement member by the first urging means is made smaller than the urging force of the disengagement member by the second urging means. 3. The first abutting portion is an opening having a narrow width in the urging direction of the first urging means, and the second abutting portion is in the urging direction of the second urging means. The clutch mechanism according to claim 1, wherein the clutch mechanism has a wide convex portion.