SU905073A1 - Safety device of petrol-engine saw - Google Patents

Description

(54) SAFETY DEVICE OF PETROL MOTOR

SAWS

one

The invention relates to auxiliary devices of portable motor saws and is intended for use on gasoline-powered tools to ensure the safety of the operator when the hand is accidentally slipping from the front control handle in the direction of the moving chain.

A safety brake of instantaneous sawing chain is known, which contains a friction clutch made with a hub interacting with a brake element in the form of a clamping tape, an actuator in the form of a lever with a cam surface located near the front saw control handle, and a working spring under the action wherein the clamping tape is in contact with the hub of the friction clutch 1.

However, such a device has a low reliability due to the structural elements that are not protected against the ingress of sawdust and dirt. In addition, the device with a clamping belt has a relatively long deceleration time, which reduces its efficiency and the effect of a band brake in one direction, radial to the crankshaft, causes a large bending moment and contributes to its fracture, as well as the destruction of the sub-holders.

A device that ensures the safety of a chain saw, comprises a lever with a lock installed in front of the control handle, having a working surface located along a helical line for interacting with the guide element, a drum and a clutch with an asterisk of the saw chain 2.

When the device is triggered, an axial displacement of the saw chain sprocket occurs, which leads to an open circuit, moving it in the guide groove. In addition, the working elements of the device are located outside the saw body, which does not exclude the possibility of the device clogging with sawdust and dirt, and this reduces the reliability of the device and does not guarantee the safety of the operator.

The purpose of the invention is to increase the reliability of the device.

Claims (2)

This goal is achieved by the fact that the screw working surface of the drum is aligned with a closed groove, and the guide element in the form of a finger has a socket for a plunger retainer, the axis of which is parallel to the axis of the drum, the latter is spring-loaded and has sleeves with a clutch and sprocket. . FIG. 1 shows a gasoline engine saw with safety device, general view; in fig. 2 shows section A-A in FIG. 1 (along the axis of the crankshaft); in fig. 3 the same, after the operation of the safety device; in fig. 4 - section bb pa fig. 2 (the lock is in the rest position). The safety device of the safety saw includes a lever 2 fixed on the case 1, mounted in front of the front control handle 3 and having a spring-loaded clamp 4. On the case 1, a clutch 6 is mounted on the shaft 5, which engages with a spring-loaded drum 7 having helix working surface groove 8 for engagement with the guide member. The guide element is designed as having a pin 9 and a slot 10 for a clamp 4 of the plunger 11. The axis of which is parallel to the axis of the drum 7. The drum 7 has a splined connection with an asterisk 12 of the saw chain. The device operates as follows. In the initial position, the lever 2 is close to the front control handle 3 of the saw, the clamp 4 is located near the plunger 11. When the saw is operating, the clutch 6 of the clutch 6 and the drum 7 entering into the splined engagement rotate; the drum 7 transmits the torque to the sprocket star 12 and imparts a reciprocating movement to the plunger 11 via a finger 9 interacting with the groove 8. When the operator pushes the operator’s arm, the lever 2 releases the spring-loaded clamp 4, which moves down and locks the plunger in the far position from the clutch 11. The finger 9, which interacts with the groove 8 of the drum 7 which continues to rotate, causes the latter to move along the axis of the shaft 5 from the clutch 6, as a result of which the drum 7 is disengaged from the clutch 6, but remains in engagement with the drive 12. Thus, the connection between the motor shaft and the saw chain is broken. After that, the drum 7, together with the asterisk 12, self-brakes, pressing against the end face of the saw body 1, and stops the saw chain moving by inertia. The coupling of the drum with the sprocket by means of the clutch 6 is carried out automatically after the lever 2 is set in the initial position due to the fact that the drum 7 is spring-loaded. The use of this device eliminates damage to the saw chain when the device is triggered, and increases the reliability of the safety device by isolating it in the saw case. The saw chain stops in half a shaft revolution, which at 0.00 rotations of the engine at 6000 rpm is 0.005 s. Claims The safety device of a gasoline-powered saw has a locking lever mounted in front of the control handle, having a working surface arranged along a helical line for interacting with the guide element, a drum and a coupling with an asterisk saw chain, characterized in that , the screw working surface of the drum is made in the form of a closed groove, and the guide element in the form of a finger with a socket for a plunger retainer, the axis of which is parallel to the axis drum, the latter being spring loaded and has schlitsevye compound with clutch engaging the chain and the sprocket. Sources of information taken into account in the examination 1. US patent number 3934345, cl. B 27 B 17/00, 1976. 2. US patent number 3839795, cl. B 27 B 17/00, 1974 (prototype).