SU935273A2 - Portable motor saw - Google Patents

Description

(54) PORTABLE MOTOR SAW

one

The invention relates to portable motor saws and can be used in the forest industry.

According to the main author. St. No. 785033 is a known portable motor saw comprising an engine body, a sawing apparatus, a gas tank and control handles rigidly connected to a support frame, having a base hollow rack, shock absorbers connecting the rack to the support frame, a rod mounted in the rack, the upper end of which has a weight and the bottom is rigidly connected to the base of the rack, spring-loaded relative to the base of the rack, a sleeve connected by a cable with a stop pivotally mounted on the housing of the engine. In this motor saw, the main harmonics of the overturning moment of the two-wheel drive on operating mode and idling 1 are reduced.

However, the additional harmonics of this point are not damped, which does not allow for a highly effective reduction of the vibration level on the motor and chainsaw handles.

The aim of the invention is to increase the efficiency of vibration damping on the engine and the handles.

The goal is achieved by the fact that the load is made in the form of a glass, inside which an elastic rod is installed along the axis, the middle part of which is rigidly connected to the walls of the glass by means of a web, and the ends are supplied with additional weights.

FIG. 1 shows a portable motor-saw, general view; in fig. 2 is a view A of FIG. one.

Claims (1)

The portable ornament saw contains an engine body 1 rigidly connected to the saw unit 2 and a stand 3 made in the form of a pipe. The gas tank 4 and the control arms 5 are rigidly connected to the support frame 6, which is connected to the column 3 by elastic elements 7 in the form of cylindrical equal-spring springs arranged evenly around the circumference, the center of which coincides with the center of gravity of the frame 6. There is a dynamic vibration damper inside the rack 3 in the form of a rod 8, the lower end of which is rigidly connected with the base 9 of the rack 3, and the upper end with a load 10. The vibration damper is equipped with a mechanism for changing the stiffness of the rod 8, made in the form of a sleeve 11 installed between the rack 3 and the Ster There is an 8m displacement along the axis of the rod 8 there. A spring 12 is installed between the sleeve 11 and the stand base. The secter of the stop 13 is connected to the engine body 1 by a joint 14 and an elastic connection, for example a flat spring 15, which is mounted with tension, and is located in the groove 16 of the engine housing 1. Restriction of the sector of the stop 13 is provided by the protrusion 17. The sector of the stop 13 is connected by means of a flexible cable 18 with the sleeve 11. The load 10 is made in the form of a glass with a gear 19, inside which an elastic rod 20 is installed along the axis part of which is rigidly connected with the jumper 19, and additional weights 21c 22 are fixed at the ends. 22. The operation of the portable motor saw is carried out as follows. The motor 1 generates spatial oscillations that are transmitted through the strut 3 and the elastic members 7 to the support frame b. In idle mode, the sector of the stop 13 does not rest against the wood, the spring 15 pushes the sector 13 along the groove 16 until it touches the protrusion 17. The flexible cable 18, Overcoming the resistance of the spring 12, moves the sleeve 11 towards the base 9 of the rack 3. Length of the working part The rod 8 is increased, which leads to a decrease in the natural frequency of the dynamic damper so that it is equal to the frequency of the first harmonic of the tilting moment acting from the engine during idling. When sawing wood under the action of cutting forces and pushing the sector of the stop 13, moving, compresses the spring 15, which weakens the tension of the cable 18, and the spring 12 moves the sleeve II along the rod, reducing its working length a. In this case, the natural frequency of the dynamic damper is increased to a value equal to the frequency of the first harmonic of the tilting moment of engine 1 in the operating mode. The additional weights 21 and 22, fixed on the elastic rod 20, serve as additional dynamic dampers forming resonant oscillatory circuits, the eigenfrequencies of which are chosen to be equal to the frequencies of the high harmonics of the tilting moment of the engine when it is idling and working. Thus, to reduce the second harmonic of the tilting moment at idle mode, the mass of the load 22 and the length of the lower part of the elastic rod 20 are selected from condition 2i) (K / tU and in the operating mode of the load mass 21 and the length of the upper part of the elastic rod 20 is selected from 2t / r (к, / гт1, Пгде оГх, оГр - angular velocities of the crankshaft at idle and working modes; K, Kg - stiffness coefficients of the lower and upper sections of the elastic rod 20; t, t ,, - the mass of additional weights 22 and 21. Thus, the main dynamic absorber in the form of a group and 10 on the rod 8 with a variable length a, as well as additional dynamic dampers in the form of additional weights 21 and 22 on the elastic rod 20, oscillated in antiphase with the angular oscillations of the engine, reduce the amplitudes of the angular oscillations of the latter from the first and second harmonics of the engine's torsional moment at the same time on the idle and working modes, which allows to significantly reduce the vibration amplitudes on the handles of the support frame, i.e., to improve the quality performance, motor saws. Formula of the invention Portable motor-saw on the author. St. No. 785033, characterized in that, in order to increase the efficiency of vibration damping, the load is made in the form of a glass, inside which an elastic rod is installed along the axis, the middle part of which is connected to the walls of the glass by means of a jumper, and the ends are provided with additional weights. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 785033, cl. B 27 B 17/00, 1979.