JP2813388B2 - Centrifugal governor - Google Patents

Description

The present invention relates to a centrifugal governor.

2. Description of the Related Art Conventionally, for example, centrifugal governors using fly weights have been used to prevent high-speed idling of gasoline engines.However, conventional centrifugal governors have a considerably complicated structure and a main part of the engine. It is attached to the crankshaft in the crankcase to be configured, and therefore, the axial length of the crankcase is large, making it difficult to reduce the size of the engine, and hindering the common production of the main engine part. .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a centrifugal governor of a simple and convenient shape while eliminating the disadvantages of the prior art as described above.

Means for Solving the Problems The centrifugal governor according to the present invention has a clutch drum attached to an outer end of a rotating shaft via a first rotating resistor and a centrifugal clutch member fixed thereto. A second rotating resistor, which the centrifugal clutch member can contact by the action of centrifugal force at a predetermined number of rotations of the rotating shaft, is attached, and the clutch drum is connected to a rotation control member via an interlocking mechanism. Is done.

Therefore, for example, at a normal rotation speed of the engine whose rotation is to be controlled, the rotation of the crankshaft, which is the rotation shaft, is transmitted to the clutch drum only through the first rotation resistor, but the rotation resistance is reduced. But the clutch drum does not rotate. However, when the idling speed of the engine exceeds the above-mentioned normal rotation speed and rises to a predetermined rotation speed, the centrifugal clutch member comes into contact with the second rotation resistor, so that the rotation of the crankshaft is reduced to the first and second rotation speeds. The rotation is transmitted to the clutch drum by both rotation resistances of the rotation resistor, and the rotation is transmitted to the throttle valve, which is a rotation control member, via the interlocking mechanism, and the throttle valve is operated in the direction of the closed position. To control the idling speed of the engine.

Embodiment Next, the present invention will be described based on an embodiment of the drawings.

The illustrated embodiment is an example in which the present invention is applied to a centrifugal governor of a relatively small two-stroke engine used for a work machine carried and carried by an operator, for example, a backpack brush cutter or a chain saw. However, the present invention can also be applied as a centrifugal governor for equipment other than the engine as described above.

The illustrated embodiment, as shown in FIGS. 1 and 2,
Crankcase 1 that constitutes the main part of a two-stroke engine
A starter case 4 of the recoil starter 3 is fixed to the outside of one end 2 of the starter. The crankcase 1 rotatably supports a crankshaft 5, and one end 6 of the crankshaft 5 projects from the end 2 of the crankcase 1 into the starter case 4. The flange member 7 fixed to the end 6 of the crankshaft 5 has a spring biasing pawl member 8 pivotally attached to an eccentric portion thereof. The starter case 4 has a boss portion 9 disposed therein coaxially near the end 6 of the crankshaft 5, the boss portion 9 rotatably supporting a recoil drum 10. I have. The recoil drum 10 has a recoil rope 12 wound around its circumferential groove 11, and a tip (not shown) of the recoil rope 12 extends from the starter case 4 to the outside. A spring 13 is provided between the starter case 4 and the recoil drum 10, and the spring 13 applies a spring force in a direction in which the recoil rope 12 is wound around the recoil drum 10. The recoil drum 10 is formed integrally with a ratchet wheel 14. The ratchet wheel 14 is engaged with the biasing pawl member 8 to transmit the rotational force of the recoil drum 10 to the crankshaft 5. When the engine is started, the recoil rope 12 is pulled out of the starter case 4 against the action of the mainspring 13 to rotate the recoil drum 10, and the rotational force is applied to the flange through the ratchet wheel 4 and the pawl member 8. The engine is started by rotating the member 7 and the crankshaft 5. When the rotation of the crankshaft 5 increases, the claw member 8 is automatically disengaged from the ratchet wheel portion 14 by centrifugal force. The configuration and operation of the engine and the recoil starter 3 described so far are the same as those of the conventionally known type.

However, in the illustrated embodiment, the centrifugal governor is located between the recoil starter 4 and one end 2 of the crankcase 1.
15 are provided. The centrifugal governor 15 is provided on the boss portion 16 of the flange member 7 with a first turning resistor, for example, a first turning resistor.
And a clutch drum 18 rotatably supported via a contact-type seal bearing 17. The inner and outer members of the first rotation resistor, that is, the first seal bearing 17
The inner race 19 and the outer race 20 are fixed to the boss portion 16 and the clutch drum 18 of the flange member 7, respectively. The outer surface of the clutch drum 18 is fixed to an outer member of a second turning resistor, for example, an outer race 22 of a second contact-type seal bearing 21. Further, a pair of one-piece centrifugal clutch members 23 are directly attached and fixed to the boss portion 16 of the flange member 7 at the inner ends thereof, and the centrifugal clutch members 23 are centrifugally generated by rotation of the crankshaft 5. It is configured to be moved radially outward by a force in a direction of contacting the inner member of the second rotation resistor, that is, the inner race 24 of the second seal bearing 21. The first and second
The relationship between the rotational speed and the rotational force (resistance) of the seal bearings 17 and 21 changes along curves A and B in the characteristic diagram of FIG. 3, respectively, and the curves A and B indicate the variation width of each bearing. C and D, respectively. The predetermined number of revolutions at point E in the characteristic diagram of FIG. 3 is a clutch-in point at which the clutch member 23 contacts the inner race 24 of the second seal bearing 21.

Further, the centrifugal governor 15 has a drive gear 25 integrally formed on the outer peripheral outer surface of the clutch drum 18.
Reference numeral 25 is engaged with a driven large gear 26 which is instructed to be rotatable by the starter case 4. The driven large gear 26 fixes a small gear 27 coaxially therewith. The small gear 27 meshes with a sector gear 28 rotatably supported on the starter case 4 side. The sector gear 28 forms a lever 29 at its end, the tip of which is connected to the throttle valve 30 of the engine. The driving and driven large gears 25 and 26, the small gear 27, the sector gear 28 and the lever 29 increase the rotational force of the driving gear 25 and transmit it to the lever 29 to easily rotate the throttle valve 30. Form a boost interlocking mechanism.

When the engine is started in the above-described manner and at the normal predetermined rotational speed, the crankshaft 5 is rotating at a lower rotational speed than the clutch-in point E in the characteristic diagram of FIG. Is radially inwardly spaced from the inner race 24 of the second seal bearing 21, the rotation of the crankshaft 5 is transmitted to the clutch drum 18 via only the first seal bearing 17, and this rotation resistance is Third
It increases along the line OF in the characteristic diagram, but is too small to rotate the clutch drum 18 so that the clutch drum 18 remains stationary. When the engine speed increases for some reason and reaches the clutch-in point E,
The clutch member 23 comes into contact with the inner race 24 of the second seal bearing 21. Therefore, the rotation of the crankshaft 5 is caused by the combined rotation resistance of the first and second seal bearings 17 and 21. The transmission of the rotational force from the crankshaft 5 to the clutch drum 18 increases sharply to the point G along the line FG in the characteristic diagram of FIG. The rotation tends to increase, and thus the torque on the clutch drum 18 tends to increase along the line GH in the characteristic diagram of FIG. As a result, the clutch drum 18 starts to rotate by receiving a rotational force greater than the bias pressure of the return spring (not shown) of the throttle valve 30 at the point G, and starts to rotate. Is rotated in the direction of arrow J in FIG. 2, whereby the throttle valve 30 is rotated toward the closed position to reduce the amount of air-fuel mixture supplied to the engine, and the overspeed of the engine is reduced to the normal predetermined speed. Return to automatically.

Effect of the Invention With the configuration of the present invention described above, the present invention enables the centrifugal governor to be arranged outside the main part of the device such as the engine so that the main part of the device can be downsized and the main part can be shared. Since it enables production and controls the number of rotations at the clutch-in point of the centrifugal clutch member, it can prevent performance changes due to variations in the rotating resistor, and the interior shape of the main part becomes simple. When it is applied to an engine, it has effects such as not deteriorating low-speed stability and acceleration performance.

[Brief description of the drawings]

1 is a cross-sectional view of a main part of a centrifugal governor showing an embodiment according to the present invention, FIG.
FIG. 3 is a characteristic diagram showing the relationship between the rotational speed and the rotational force in the embodiment shown in FIGS. 1 and 2. 5 ... crankshaft, 15 ... centrifugal governor, 17 ... first contact type seal bearing, 18 ... clutch drum, 21 ...
... Second contact type seal bearing, 23 ... Centrifugal clutch member, 25,26 ... Gear, 27 ... Small gear, 28 ... Sector gear, 29 ... Lever, 30 ... Throttle valve.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 31/00 301 F02D 1/00 F02D 11/04

Claims (1)

(57) [Claims] 1. A clutch drum (18) is attached to an outer end (6) of a rotating shaft (5) via a first turning resistor (17), and a centrifugal clutch member (23) is fixed to said clutch. A second turning resistor (21) is attached to the drum so that the centrifugal clutch member can contact by the action of centrifugal force at a predetermined rotation speed (E) of the rotating shaft (5), and the clutch drum is interlocked. A centrifugal governor connected to the rotation control member (30) via a mechanism (25, 26, 27, 28, 29).