JPH074342Y2 - Spring clutch - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a spring clutch that automatically operates by utilizing centrifugal force, and in particular, slippage is eliminated in the normal rotation range and the clutch is completely engaged. The present invention relates to a spring clutch in which rotation and torque of a prime mover are transmitted as they are, and a so-called half-clutch state is realized at the time of acceleration until reaching a normal rotation range to achieve smooth power transmission.

[Conventional technology]

For example, a centrifugal clutch, which is often used in a power working machine equipped with a small internal combustion engine as a prime mover, has a clutch boss connected to a drive shaft and a clutch boss arranged concentrically with the clutch boss and rotating independently of the clutch boss. A clutch drum, a plurality of clutch shoes mounted on the clutch boss so as to be movable in the radial direction, and a spring for biasing each clutch shoe inward in the radial direction. As the speed increases, the centrifugal force acting on the clutch shoe causes the clutch shoe to move radially outward against the action of the spring, thereby frictionally engaging the clutch drum and transmitting the rotational force to the clutch drum. (See, for example, Japanese Utility Model Laid-Open No. 62-81731).

[Problems to be solved by the device]

The conventional centrifugal clutch as described above operates smoothly due to the sliding frictional engagement even when the inertia on the output shaft side is large at the start of the rotational force transmission, but this slipping phenomenon occurs at the low speed side in the normal rotation range. Transmission efficiency decreases,
In some cases, the target low speed rotation and sufficient torque transmission could not be obtained.

Therefore, it may be possible to completely eliminate the slip phenomenon, but in that case, if the inertia on the output shaft side is large, the operation at the start of torque transmission will not be smooth, and for example, When used in a brush cutter or the like, there is a possibility that the engine, which is the prime mover, may stop when the torque transmission starts.

Further, the conventional centrifugal clutch as described above has a complicated structure, and includes a clutch boss, a clutch drum, a clutch shoe,
Since various parts such as springs are required, it takes time and effort to manufacture them, and they are expensive, and there is a limit to the reduction in size and weight.

The present invention aims to provide a spring clutch that eliminates slippage in the normal rotation range and efficiently transmits the rotation and torque of the engine as it is while the clutch is completely engaged, and further reaches the normal rotation range. The purpose is to provide a spring clutch that achieves a so-called half-clutch state during smooth acceleration to achieve smooth power transmission. Furthermore, there is little impact at the start of torque transmission, and the configuration is extremely simple and inexpensive. It is also an object of the present invention to provide a spring clutch that can be reduced in size and weight.

[Means for Solving the Problems]

In order to achieve the above object, a spring clutch of the present invention is fitted between an input shaft and an output shaft, and a coil spring having an output shaft side end fixed to the output shaft is provided on the input shaft side. And a state in which the input shaft is rocked by a centrifugal force at a predetermined low rotation speed to be locked to the input shaft side end portion of the coil spring to tighten the coil spring and a state in which the lock is released. A first centrifugal claw that repeats and
It is provided on the input shaft side and swings by centrifugal force at a predetermined high rotation speed of the input shaft to be completely locked to the input shaft side end portion of the coil spring regardless of the operation of the first centrifugal pawl. And a second centrifugal pawl for keeping the coil spring tightened.

[Action]

According to the present invention, for example, when the internal combustion engine is idling (including when the engine is stopped), as shown in FIG. 2, the first rotor provided on the side surface of the magnet rotor fixed to the crankshaft (input shaft).
The tip of the centrifugal claw and the tip of the second centrifugal claw are in a state of being disengaged from the bent portion (end) of the coil spring on the crankshaft side.

Therefore, even if the crankshaft and the magnet rotor are rotated at low speed (idling), the crankshaft end is idling in the coil spring, and the transmission shaft (output shaft)
Rotation is not transmitted to the side.

When the rotation speed of the internal combustion engine is increased from idling rotation, when the crankshaft and the magnet rotor reach a predetermined low rotation speed, as shown in FIG. 3, the first centrifugal pawl provided on the side surface of the magnet rotor is rotated. The rear end is moved outward by the centrifugal force, and conversely, the front end of the first centrifugal pawl is moved to the inner crankshaft side. At this time, since the predetermined high rotation speed has not been reached yet, the tip of the second centrifugal pawl is in a state of being disengaged from the bent portion of the coil spring on the crankshaft side.

Therefore, each time the tip of the first centrifugal pawl tries to overtake the bent portion of the coil spring as the crankshaft and the magnet rotor rotate, the tip of the first centrifugal pawl breaks. The coil spring is fastened by being locked to the bent portion, and each time the crankshaft and the magnet rotor are further rotated, the tip of the first centrifugal claw passes over the bent portion of the coil spring to lock the coil spring. Is released, these states are repeated, so to speak, a so-called half-clutch state, and even if the inertia on the transmission shaft side is large, power is smoothly transmitted and the transmission shaft is gradually accelerated.

Then, when the rotation speed of the internal combustion engine further increases and the crankshaft and the magnet rotor reach the normal rotation range (working rotation range), that is, when a predetermined high rotation speed is reached, as shown in FIG. The rear end of the provided second centrifugal claw is also moved outward by the centrifugal force, and conversely the second centrifugal claw is moved outward.
The tip of the centrifugal claw is moved inward toward the crankshaft. At this time, since the predetermined low rotation speed has already been exceeded, the tip of the first centrifugal pawl maintains the state of being moved to the crankshaft side.

Therefore, since the tip of the first centrifugal pawl does not always continue to be locked to the bent portion of the coil spring even if it moves to the crankshaft side, the second centrifugal pawl as shown in FIG. The coil spring gradually tightens the crankshaft and the transmission shaft until the tip of the coil spring is completely locked in the bent portion of the coil spring, and finally the crankshaft and the transmission shaft are integrated by the coil spring. The rotary force of the crankshaft is smoothly and efficiently transmitted to the transmission shaft.

As described above, in the present invention, the power transmission by the second centrifugal pawl is not by frictional engagement, so if the predetermined high rotation speed is set in advance as the rush rotation speed into the normal rotation range,
There is no room for the slip phenomenon even at a relatively low rotation speed in the normal rotation range, and the rotation and torque of the engine are transmitted as they are while the clutch is completely engaged.

Further, as described above, in the present invention, the so-called half-clutch state is realized by the first centrifugal pawl during acceleration until reaching the normal rotation range, so that power transmission can be smoothly performed even if the inertia on the transmission shaft side is large. There is no risk that the engine will stop and the parts will be impacted.

Further, since the coil springs are wound and coupled as described above, the shock can be sufficiently absorbed even at the start of transmission.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to the drawings.

The present embodiment is an example of a power plant using a small air-cooled two-cycle engine 3 as a prime mover, and a crankshaft 1 as an input shaft and a transmission shaft 2 as an output shaft are linearly disconnected from each other with a small gap S therebetween. Is provided.

The crankshaft 1 is supported by a bearing 5 provided in a crankcase 4 that constitutes the engine 3, and a magnet rotor 6 is fixed at a proper position in the end direction thereof.

Reference numeral 7 in the drawing denotes a power generating coil for the ignition device.

Further, the transmission shaft 2 is supported by a bearing 9 provided on a cover 8 integrally fixed to the crankcase 4, and a connecting portion 2a of an extension transmission shaft 10 is formed at an outer end portion thereof.

Reference numeral 11 in the figure denotes a transmission shaft cover, which is an operating rod in a brush cutter or the like.

In the present invention, the coil spring 12 reversely wound in the rotational direction of the crankshaft 1 is loosely fitted over the outer end of the crankshaft 1 and the inner end of the transmission shaft 2 which are linearly provided, The transmission shaft side end 12a of the coil spring 12 is fixed to the transmission shaft 2.

That is, the transmission shaft 2 is fixed to the pin 13 provided by press fitting, screwing or the like in advance.

Further, a bent portion 12b extending parallel to the crankshaft 1 is formed at an end of the coil spring 12 on the crankshaft 1 side.

Next, on the outer surface of the magnet rotor 6 provided on the crankshaft 1, the crankshaft 1 swings by centrifugal force when the crankshaft 1 is at a predetermined low rotation speed or more, and the tip 14a of the coil spring 12 is bent. A first centrifugal pawl 14 is provided which repeats a state in which the coil spring 12 is wound and fastened by being locked to the bent portion 12b and a state in which the locking is released.

The operating state of the first centrifugal pawl 14 is shown in FIGS.

The first centrifugal pawl 14 is formed in a substantially V shape as a whole, and the front end 14a side engaging with the bent portion 12b of the coil spring 12 is made short and the rear end 14b side is made long at a predetermined rotation speed. Rear end 1
4b is configured to be moved outward by a centrifugal force, and a biasing spring 16 is provided between a pivot pin 15 screwed to the magnet rotor 6 and an outer surface of the magnet rotor 6.
Is provided so as to be swingable.

As shown in FIG. 2, the tip end 14a of the first centrifugal pawl 14 is bent by the biasing spring 16 when the rotational speed is lower than a predetermined low rotational speed (when idling and when stopped). It is designed to remain completely off 12b.

That is, in the embodiment shown in the drawings, a stopper 17 is provided on the outer side surface of the magnet rotor 6 on the outer side of the tip 14a of the first centrifugal claw 14, and the one end 16a of the biasing spring 16 is locked to the stopper 17. Then, the other end 16b of the biasing spring 16 is fixed to the rear end 14b of the centrifugal pawl 14, and the first centrifugal pawl 14 is always in the clockwise direction when viewed in the drawing.
It is configured to be biased to the side and to be maintained in the regulated state shown in FIG. 2 by the stopper 17.

Further, a stopper 18 is also provided outside the rear end 14b of the first centrifugal pawl 14. When the crankshaft 1 has a predetermined low rotation speed, in other words, when the magnet rotor 6 has a predetermined low rotation speed, the stopper 18 resists the force of the biasing spring 16 by a centrifugal force to keep the rear end 14b of a predetermined amount. It is moved and locked only, and further unnecessary movement is restricted as shown in FIGS. 3 and 4.

Then, in this restricted state, a state in which the tip 14a of the first centrifugal claw 14 is locked to the bent portion 12b of the coil spring 12 to tighten the coil spring 12 and a state in which the locking is released are repeated. It is a thing. That is, in the case of the embodiment shown in the drawings, a relatively large chamfered portion 14c is formed inside the tip 14a of the first centrifugal claw 14, and the chamfered portion 14c extends from the tip side to the rear end side in the restricted state. The distance to the center of the crankshaft 1 is gradually reduced, and the tip 14a of the first centrifugal pawl 14 is bent by the coil spring 12 as the crankshaft 1 and the magnet rotor 6 rotate. Each time it tries to overtake the bent portion 12b, the coil spring 12 is gradually locked from the tip end side of the chamfered portion 14c of the tip end 14a to the rear end side of the bent portion 12b of the coil spring 12 so that the coil spring 12 is tightened. Each time the crankshaft 1 and the magnet rotor 6 are further rotated, the bent portion 12 of the coil spring 12 is rotated.
The b slides along the chamfered portion 14c of the tip 14a, disengages from the rear end side thereof, and the locking is released.

Further, the crankshaft 1 has a predetermined high rotation speed (normal rotation range plunging rotation speed) on the outer surface of the magnet rotor 6.
At the above time, the bent portion 12 of the coil spring 12 is rocked by the centrifugal force regardless of the operation of the first centrifugal pawl 14.
A second centrifugal pawl 19 is provided which is fully engaged with b to keep the coil spring 12 tightened.

The operating state of the second centrifugal pawl 19 is also shown in FIGS.

The second centrifugal pawl 19 is also formed in a substantially V shape as a whole, and the front end 19a side that engages with the bent portion 12b of the coil spring 12 is made short and the rear end 19b side is made long and at a predetermined high rotational speed. The rear end 14b is constructed so that it can be moved outwardly by centrifugal force, and the pivot pin 20 is screwed to the magnet rotor 6
In addition, a bias spring 21 is interposed between the magnet rotor 6 and the outer surface of the magnet rotor 6 so as to be swingable.

When the rotational speed of the biasing spring 21 is lower than a predetermined high rotation speed, the tip 19a of the second centrifugal pawl 19 is completely removed from the bent portion 12b of the coil spring 12, as shown in FIGS. It is configured to maintain a stable state.

That is, in the illustrated embodiment, the first centrifugal pawl
Similar to the case of 14, a stopper 22 is provided on the outer side surface of the magnet rotor 6 outside the tip end 19a of the second centrifugal pawl 19, and the stopper 22 is provided with one end 21a of the biasing spring 21.
And the other end 21b of the biasing spring 21 is fixed to the rear end 19b of the second centrifugal pawl 19 and the second centrifugal pawl 19 is locked.
Is always urged in the clockwise direction as viewed in the figure toward the stopper 22 side, and the stopper 22 maintains the regulated state shown in FIGS. 2 and 3. Note that the biasing spring 21 has a larger spring force than the biasing spring 16 for the first centrifugal pawl in consideration of the difference in rocking start rotational speed from the first centrifugal pawl 14. Or, change the shape of the centrifugal claw.

Further, a stopper 23 is also provided outside the rear end 19b of the second centrifugal pawl 19. When the crankshaft 1 has a predetermined high rotation speed, in other words, when the magnet rotor 6 has a predetermined high rotation speed, the stopper 23 resists the force of the biasing spring 21 by a centrifugal force, and the rear end 19b has a predetermined amount. It is moved and locked only and regulates unnecessary movement.

Then, in this restricted state, the tip end 19a of the second centrifugal pawl 19 is completely locked to the bent portion 12b of the coil spring 12, and the coil spring 12 gradually tightens the crankshaft 1 and the transmission shaft 2. The crankshaft 1 and the transmission shaft 2
Are integrally connected. In addition, in order to maintain the state in which the tip 19a of the second centrifugal claw 19 is completely locked to the bent portion 12b of the coil spring 12 in the restricted state, the second centrifugal Nail 19
The chamfer of the tip 19a of the tip of the first centrifugal claw 14
It is smaller than the chamfered portion 14c.

[Effect of device]

According to the present invention, there is no slip even at a relatively low rotation speed in the normal rotation range, and the effect that the rotation torque on the input shaft side is efficiently transmitted as it is while the clutch is completely engaged.

Also, during acceleration until reaching the normal rotation range, a so-called half-clutch state is realized, smooth power transmission is performed, and an effect such as engine stop etc. does not occur even if inertia on the transmission shaft side is large. Is.

Further, the present invention has effects such as a small impact even at the start of transmission of the rotational force, an extremely simple structure and a low cost, and a reduction in size and weight.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an essential part, and FIGS. 2, 3, and 4 are front views of the essential part of FIG. The figure shows a non-rotation state, FIG. 3 shows a half-clutch state, and FIG. 4 shows a rotation transmission state. 1 ... input shaft (crank shaft), 2 ... output shaft, (transmission shaft), 12 ... coil spring, 12a ... output shaft side end, 12b ... input shaft side end (folded part), 14 …… First centrifugal claw, 19 …… Second centrifugal claw.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-51625 (JP, A) JP-A 61-140625 (JP, A) Actual development Shou 62-20028 (JP, U) JP-B 44- 18763 (JP, B1)

Claims (1)

[Scope of utility model registration request] 1. A coil spring 12 fitted between an input shaft 1 and an output shaft 2 and having an output shaft side end 12a fixed to said output shaft 2, and a coil spring 12 provided on said input shaft 1 side. When the input shaft 1 is rotated at a predetermined low rotational speed by centrifugal force, the input shaft 1 is locked to the input shaft side end 12b of the coil spring 12 and the coil spring 12 is wound and tightened. The first centrifugal claw 14 that repeats the above-described state and the input shaft 1 is provided. The first centrifugal claw 14 swings by the centrifugal force at a predetermined high rotation speed of the input shaft 1 regardless of the operation of the first centrifugal claw 14. A second centrifugal pawl 19 that completely locks the coil spring 12 on the input shaft side end 12b of the coil spring 12 to maintain the coil spring 12 in a tightly wound state.