JP2011214513A - Engine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine tool reducing vibrations transmitted to a worker with reciprocation of a piston and maximizing operability and working efficiency.SOLUTION: The engine tool includes the piston 9 reciprocating between a top dead center and a bottom dead center under the guidance of a cylinder 17, a dynamic vibration absorber having a weight 24 driven in a fashion antiphase to the reciprocation of the piston 9 and elastic bodies 25a, 25b connected to the weight 24, and housing parts 22, 23 housing the dynamic vibration absorber. The engine tool further includes a communication passage for bringing the cylinder 17 into communication with the housing part 22 when the piston 9 lies near the top dead center.

Description

  The present invention relates to an engine tool using a two-cycle or four-cycle engine such as a chain saw, a blower, and a brush cutter.

  In the engine tool, the piston descends all at once in the cylinder by rapid pressure expansion due to combustion of the compressed mixed gas in the combustion chamber. Since the piston is connected via a connecting rod to a crankpin that is eccentric from the center of the crankshaft, an inertial force due to the mass of the connecting rod and the piston is generated due to rapid pressure expansion. Similarly, when the piston is raised, an inertial force is generated due to the mass of the connecting rod and the piston. For this reason, since the inertial force due to the mass causes the vibration, the counterweight is provided in the crank to cancel the inertial force between the piston and the crank, thereby reducing the vibration caused by the movement of the piston.

  However, since the vibration in the direction orthogonal to the moving direction of the piston is generated due to the imbalance of the counterweight, the vibration cannot be completely canceled. Therefore, the engine tool uses an elastic body such as a rubber or a spring to attenuate the vibration transmitted to the handle while the vibration generated by the engine is transmitted to the part gripped by the operator, that is, the handle. Absorbing vibration.

  Further, as described in Japanese Patent Application Laid-Open No. 2009-275836 (Patent Document 1), an engine tool including a dynamic vibration absorber has been proposed as a mechanism for reducing vibration. The dynamic vibration absorber exerts a vibration damping action by driving a weight arranged in a state where an urging force is applied by an elastic element according to the amount of vibration input to the dynamic vibration absorber.

JP 2009-175836 A

  The main source of vibration is the inertial force of the piston due to rapid pressure expansion in the cylinder. Therefore, in the conventional structure as described above, the counterweight is used to cancel the inertial force due to the reciprocating motion of the piston. However, the counterweight inertial force works in the direction perpendicular to the piston moving direction. Therefore, the counterweight itself becomes a source of vibration. Since the counterweight is determined in consideration of the balance between the piston moving direction and the inertial force in the vertical direction, there is a limit in offsetting the piston inertial force due to rapid pressure expansion in the cylinder.

  Further, since the inertia force of the counterweight is substantially a sine wave with respect to the moving direction of the piston, the maximum effect is exhibited at the top dead center and the bottom dead center. The pressure in the cylinder becomes maximum immediately before top dead center, and the thrust (inertial force) of the piston due to rapid pressure expansion in the cylinder cannot be offset efficiently.

  Therefore, the present invention is equipped with a dynamic vibration absorber that is relatively interlocked with the vertical movement of the piston, and controls the dynamic vibration absorber according to the piston position for rapid pressure expansion in the cylinder that occurs near the top dead center of the piston. Accordingly, an object of the present invention is to provide an engine tool that can improve the vibration damping performance of the engine tool, reduce vibration transmitted to the worker, and maximize the operability and work efficiency.

  The object is to provide a piston that reciprocates between top dead center and bottom dead center, a cylinder that guides the reciprocation of the piston, a crank connected to the piston, a crank chamber that houses the crank, and the piston. A dynamic vibration absorber having a weight driven in an opposite phase to the reciprocating motion of the motor and an elastic body connected to the weight, and a housing portion for housing the dynamic vibration absorber, and the piston is located near the top dead center In this case, this can be achieved by providing a communicating portion that communicates the crank chamber with the accommodating portion.

  By setting it as such a structure, the vibration which arises by rapid pressure expansion in a cylinder can be effectively canceled by a dynamic vibration absorber, and the vibration transmitted to an operator can be reduced.

  The accommodating portion is divided by the weight into a first air chamber located above the weight and a second air chamber located below the weight, and the communication portion is separated from the first air chamber. It is desirable to communicate.

  With such a configuration, when the weight is positioned on the second air chamber side as the piston rises, the weight can be rapidly increased by connecting the crank chamber and the second air chamber by the communication portion. Therefore, the largest vibration can be reliably reduced.

  A first communication passage connecting the crank chamber and the second air chamber, wherein the weight is reciprocated in the accommodating portion in response to pressure fluctuation in the crank chamber caused by reciprocation of the piston; It is preferable.

  With such a configuration, the weight can be reciprocated in a phase opposite to that of the piston in conjunction with the reciprocation of the piston, so that vibration can be effectively reduced.

  In addition, it is preferable that the piston has a second communication passage that communicates with the second air chamber and the outside when the weight rises in the housing portion by moving to the bottom dead center side.

  By setting it as such a structure, blowby gas can be discharged | emitted via a 2nd communicating path.

  Further, it is preferable to further include an oil chamber for containing oil, and to have a third communication path that connects the oil chamber and the first air chamber by positioning the piston near the top dead center.

  With such a configuration, the oil can be supplied to the air chamber, so that the weight can be lubricated.

  In addition, it is preferable that the third communication path and the communication portion communicate with each other when the piston is located near the top dead center.

  With such a configuration, oil is sucked into the crank chamber using the pressure fluctuation in the crank chamber, so that the piston and the crank can be lubricated.

  Further, when a negative pressure is generated in the first air chamber due to the position of the weight, the oil in the oil chamber is sucked into the first air chamber through the third communication passage, and the piston It is preferable that the oil is sucked into the crank chamber when a negative pressure is generated in the crank chamber depending on the position.

  By adopting such a configuration, oil can be sucked into the first air chamber and the crank chamber, so that driving units such as weights, pistons, and cranks can be lubricated.

  Further, the first air chamber and the pulse chamber of the vaporizer are connected by a fourth communication path, and the pulse chamber may perform pulse motion due to pressure fluctuation of the first air chamber caused by reciprocation of the weight. preferable.

  With such a configuration, the fuel can be supplied with a simple configuration in conjunction with the reciprocating motion of the piston.

  Further, it is preferable that the crank is circular and a crankshaft is arranged at the center of the crank.

  By adopting such a configuration, the inertial force is not generated in the direction orthogonal to the reciprocating direction of the piston due to the rotational movement of the crank, so that the vibration generated by the reciprocating motion of the piston can be offset by the weight.

  In addition, it is preferable that the piston and the dynamic vibration absorber are arranged so as to be shifted in the radial direction of the piston with respect to the reciprocating direction of the piston, and that two dynamic vibration absorbers are provided symmetrically with respect to the piston.

  By adopting such a configuration, vibration generated by the reciprocating motion of the piston can be canceled by the weight regardless of the arrangement of the piston and the weight.

  According to the present invention, vibration caused by the reciprocating motion of the piston can be reduced, and operability and work efficiency can be maximized.

The figure which shows the chain saw of the engine tool used as this invention. 1 is a longitudinal sectional side view of an engine showing a first embodiment of an engine tool according to the present invention. It is a longitudinal cross-sectional front view of FIG. 2, and is a figure which shows the state in which a crank angle is 90 degree vicinity. The figure which shows the state in which a crank angle is 180 degree | times vicinity. The figure which shows the state whose crank angle is 270 degree vicinity. The figure which shows the state in which a crank angle is 0 degree vicinity. The figure which shows the relationship between the displacement of a weight, and a crank angle. The figure which shows the relationship between the piston and the inertia force of a counterweight in the moving direction of a piston. The figure which shows the relationship of the inertia force of the counterweight in the direction orthogonal to the moving direction of a piston. It is a longitudinal cross-sectional front view of the engine which shows 2nd Embodiment of the engine tool used as this invention, and is a figure which shows the state in which a crank angle is 0 degree vicinity. The figure which shows the state where a crank angle is 90 degree | times vicinity. The figure which shows the state in which a crank angle is 180 degree | times vicinity. The figure which shows the state whose crank angle is 270 degree vicinity. It is a longitudinal cross-sectional front view of the engine which shows 3rd Embodiment of the engine tool used as this invention, and is a figure which shows the state in which a crank angle is 0 degree vicinity. The figure which shows the state where a crank angle is 90 degree | times vicinity. The figure which shows the state in which a crank angle is 180 degree | times vicinity. The figure which shows the state whose crank angle is 270 degree vicinity.

  An embodiment of an engine tool according to the present invention will be described with reference to FIGS.

  First, an engine tool equipped with a 4-cycle engine in the present embodiment will be described. FIG. 1 shows a chain saw 1 serving as an engine tool. The chain saw 1 includes an engine case 3 in which the engine 2 is disposed, a rear handle 4 that protrudes rearward (right side in the drawing) from the engine case 3 and is connected to the rear handle 4 by a connecting portion (not shown). A front handle 5 having a substantially C shape so as to surround the power, a saw chain 7 to which power of the engine 2 is transmitted, a flat guide bar 8 for guiding the saw chain 7, and a front side (guide bar side) of the front handle 5 However, it is mainly composed of a hand guard 6 provided above the engine case 3. The rear handle 4 and the front handle 5 are configured as a unit connected by a connecting portion (not shown). The engine case 3 and the handle unit are connected to each other by a vibration isolating member (not shown), specifically, a coil spring or rubber for suppressing vibration generated by driving the engine from being transmitted to the handle unit.

  As an operation of the chain saw 1, an operator starts the engine 2 and holds the rear handle 4 and the front handle 5. By operating a throttle lever (not shown) provided on the rear handle 4, the power of the engine 2 is transmitted to the saw chain 7, and the saw chain 7 is guided by the guide bar 8 and rotated to perform a cutting operation.

  Next, the operation of the engine 2 will be described with reference to FIG. FIG. 2 is a longitudinal sectional side view of the engine 2. When the piston 9 is guided by the cylinder 17 and descends from the top dead center (upper side in the figure) to the bottom dead center (lower side in the figure), the intake valve 10 opens, and the volume of the combustion chamber 11 increases. Due to the negative pressure in the combustion chamber 11, the mixed gas is sucked from the intake port 12 due to a pressure difference from the atmosphere. As the piston 9 rises from the bottom dead center, the intake valve 10 is closed, the combustion chamber 11 is compressed, and the mixed gas is combusted and exploded by the spark of the spark plug 13, and thrust is generated in the piston 9. When the piston 9 descends from the top dead center to the bottom dead center due to the combustion / explosion of the mixed gas and then rises from the bottom dead center to the top dead center, the exhaust valve 14 is opened, and the combusted exhaust gas is discharged to the exhaust port. 15 is discharged. In this way, the working device (saw chain 7) connected to the output side of the crankshaft 16 is driven by repeating the steps of intake, compression, combustion, and exhaust of the mixed gas performed in the combustion chamber 11.

  Next, an engine tool vibration reducing structure according to the present invention will be described with reference to FIGS. 3 to 6 are longitudinal sectional front views of the engine 2, showing a state where the piston 9 is located at a different position with respect to the cylinder 17. The engine 2 is introduced into the combustion chamber 11 facing the combustion chamber 11, the piston 9 moving up and down along the longitudinal direction of the cylinder 17, the combustion chamber 11 formed by the upper surface of the piston 9 and the upper surface of the cylinder 17. And a spark plug 13 for burning and exploding the mixed gas. The piston 9 is connected by a crank 20 and a piston pin 21 via a connecting rod 19. The crank 20 is disposed in the crank chamber 18.

  Here, the crank 20 will be described. A conventional crank has a substantially fan shape with a vertex eccentric from the center of the crankshaft and a counterweight located on the opposite side of the crankshaft, and is connected to the connecting rod via a piston pin near the vertex. Has been. The crank is configured in such a way that the counterweight rotates up around the crankshaft when the piston descends and rises when the piston descends, and the counterweight descends when the piston rises. The vibration generated by the movement of the counterweight is reduced by canceling the movement of the counterweight. However, in the conventional fan-shaped crank, since the counterweight is provided eccentrically with respect to the crankshaft, the vibration cannot be completely prevented, and the counterweight itself becomes a source of vibration.

  8 and 9 are diagrams showing the relationship of vibration (inertial force) generated by the reciprocating motion of the piston when a conventional crank is used. FIG. 8 shows the relationship between the inertia force of the piston and the counterweight (crank) when the moving direction of the piston is the X direction, and the inertia force A of the piston generated in the X direction of the piston 9 and the counter generated in the X direction. The relationship between the inertial force B of the weight (crank) and the resultant force C of the piston inertial force A and the counterweight inertial force B is shown. FIG. 9 shows the inertia force D of the counterweight when the direction perpendicular to the reciprocating direction of the piston and parallel to the rotation surface of the crank is the Y direction. 8 and 9, the vertical axis represents the inertial force, and the horizontal axis represents the movement amount (crank angle) of the piston.

  In FIG. 8, the counterweight moves (inertia force B) in the opposite phase to the piston movement (inertia force A), so that the inertial force near the top dead center and bottom dead center, for example, around 180, 360 degrees. By reducing the combined force C of A and inertial force B, vibration caused by the reciprocating motion of the piston is reduced by the counterweight.

  On the other hand, as shown in FIG. 9, in the case of a fan-shaped crank, the counterweight rotates due to the counterweight imbalance, and an inertial force D is generated in the Y direction in addition to the X direction. Cannot be completely canceled out by the inertia force of the counterweight, and there is a limit to suppression of vibration. If the resultant force C in FIG. 8 is reduced to suppress the vibration in the X direction, the inertia force D (FIG. 9) of the counterweight in the Y direction increases. Conversely, if the inertia force D is reduced, the resultant force C Therefore, the inertial forces of the piston and the counterweight are offset in a balanced manner so that the inertial forces in both the X direction and the Y direction are balanced.

  Further, as shown in FIGS. 8 and 9, since the inertia force B of the counterweight is substantially a sine wave with respect to the moving direction of the piston, the maximum effect is exhibited at the top dead center and the bottom dead center. The pressure in the cylinder becomes maximum immediately before top dead center (for example, 360 degrees in FIG. 8), and the thrust (inertial force) of the piston due to rapid pressure expansion in the cylinder cannot be offset efficiently.

  In contrast, the crank 20 of the present invention has a circular shape and is configured to rotate around the crankshaft 16 when the piston 9 moves. That is, the crank 20 of the present invention is not provided for canceling the vibration (inertial force) accompanying the movement of the piston 9 as in the conventional configuration, and the reciprocating motion of the piston 9 is caused by the rotation of the crankshaft 16. Provided to convert to motion. By making the crank 20 circular, vibration (inertial force) caused by unbalance due to the shape of the crank can be eliminated. A function of canceling vibration (inertial force) generated by the reciprocating motion of the piston 9 which has been performed by the conventional crank shape (fan shape) is provided not in the crank but in a later-described dynamic vibration absorber. By configuring the dynamic vibration absorber so as to move only in the moving direction (X direction) of the piston 9, it can absorb the vibration generated by the reciprocating motion of the piston 9 without generating vibration in the Y direction, Vibration can be reliably suppressed.

  Further, according to the present invention, the inertia force can be canceled efficiently by abruptly raising the weight of the dynamic vibration absorber near the piston top dead center where the pressure in the cylinder is maximum. Can be played. Details will be described later.

  Air chambers (housing portions) 22 and 23 are formed in the crankcase 18a on both side surfaces of the crank chamber 18 (the left and right sides of the crank chamber 18 in FIG. 3). A vibration absorber is provided. The air chamber is divided into upper and lower parts in the figure by a weight 24 described later, and is composed of a first air chamber 22 located above the weight 24 and a second air chamber 23 located below the weight 24. The first and second air chambers 22 and 23 are divided by a weight 24, and the first air chamber 22 and the second air chamber 23 are not in communication with each other at normal times. The second air chamber 23 and the crank chamber 18 are connected by a communication path (first communication path) 34. Two dynamic vibration absorbers are provided symmetrically with respect to the piston 9 in the crank chamber 18a. The dynamic vibration absorber includes a weight 24 and springs 25a and 25b, which are elastic bodies having one end connected to the protrusion 24a of the weight 24 and the other end connected to the inner wall of the air chamber. The springs 25a and 25b are press-fitted and connected to protrusions 24a provided on the top and bottom of the weight 24, respectively.

  An oil chamber 27 for storing oil 26 is formed in the lower portion of the crank chamber 18. One end of the oil chamber 27 is located in the oil 26 and the other end is connected to one of the two air chambers 22 and 23 (in this embodiment, the air chamber located on the left side of the piston 9). A first passage (third communication passage) 28 is connected. In addition, the other of the two air chambers 22 and 23 (the air chamber located on the right side of the piston 9) has a second passage (second connection) in which one end opens into the air chamber and the other end communicates with the outside air. Aisle) 29 is connected. A communication path (fourth communication path) 33 connected to the pulse chamber 31 of the vaporizer 30 is connected to the upper end of the other air chamber (the first air chamber 22 located on the right side of the piston).

  As shown in FIG. 3, when the mixed gas in the combustion chamber 11 is ignited and exploded by the spark plug 13, the piston 9 descends along the longitudinal direction of the cylinder 17. When the pressure in the crank chamber 18 is compressed by the lowering of the piston 9, the crank chamber 18 communicates with the second air chamber 23 located below the weight 24 via the communication path 34, and therefore the second air The air in the chamber 23 is also compressed. As a result, since the volume change of the second air chamber 23 is larger than that of the first air chamber 22 located above the weight 24, the pressure is increased. Due to this pressure fluctuation, the weight 24 held up and down by the elastic body 25 moves in the opposite direction (upward) to the movement of the piston 9 and is provided above the weight 24 holding the moving direction of the weight 24. The elastic body 25a is compressed. Therefore, it becomes possible to cancel the inertial forces of the piston 9, the piston pin 21, and the connecting rod 19 generated by the lowering of the piston 9, and vibration can be reduced. At this time, since the pulse chamber 31 of the vaporizer 30 communicates with the first air chamber 22 via the communication path 33, the pressure of the pulse chamber 31 of the vaporizer 30 is pulsed by the movement of the weight 24 in the air chamber. Movement or pressure fluctuation occurs, and the pump diaphragm 32 is operated so that fuel can be supplied to the carburetor 30.

  Here, in the present invention, the dynamic vibration absorber is not disposed on the extension of the piston 9 in the reciprocating direction, but is displaced from the piston 9 in the lateral direction. Although the structure which provides a dynamic vibration absorber only in one place may be sufficient, the moment which generate | occur | produces by the movement of the piston 9 and the weight 24 can be canceled by providing two places with respect to the piston 9 in object. That is, since the moment generated by one weight 24 can be canceled by the other weight 24, vibration can be further reduced. Further, a dynamic vibration absorber (weight) may be provided on the extension of the piston 9 in the reciprocating direction. In this case, since there is no deviation in the radial direction of the cylinder 17 between the piston 9 and the weight 24, no moment is generated. However, it is conceivable that the dimension of the piston of the engine 2 in the reciprocating direction becomes large.

  Next, in the vicinity of the bottom dead center of the piston 9 where the pressure in the crank chamber 18 becomes maximum, the weight 24 rises as the piston 9 descends as shown in FIG. The opening 29a of the breather air passage (second passage) 29 communicating with the air is opened. The breather air passage 29 and the second air chamber 23 communicate with each other through the opening 29a, and blow-by gas leaked from the piston 9 due to combustion can be discharged to the outside.

  The air chamber is divided into a first air chamber 22 and a second air chamber 23 by a weight 24, but the first air chamber 22 and the second air chamber are located in a portion of the crankcase 18 a located on the side of the weight 24. A ventilation groove 35 communicating with the air passage 23 is formed. The ventilation groove 35 is formed longer than the dimension of the weight 24 in the longitudinal direction (movement direction). As the weight 24 rises, the first air chamber 22 and the second air chamber 23 communicate with each other through the ventilation groove 35.

  As the weight 24 rises, the blow-by bus is discharged and at the same time the ventilation groove 35 is opened. The first air chamber 22 is compressed by the lifting of the weight 24, but when the ventilation groove 35 is opened, the compressed air in the first air chamber 22 passes through the ventilation groove 35, the second air chamber 23, and the breather ventilation path 29. As a result, the pressure difference between the first air 22 and the second air chamber 23 disappears, and the weight 24 rises due to the inertia of the elastic body 25 and the weight 24.

  Next, as shown in FIG. 5, the pressure in the crank chamber 18 becomes negative as the piston 9 rises, so the pressure in the second air chamber 23 communicating with the crank chamber 18 is also negative. It becomes pressure. When the pressure in the second air chamber 23 is lower than that in the first air chamber 22, the weight 24 moves in the opposite direction to the piston 9, that is, in the downward direction in the figure, and the elastic body 25 b that holds the moving direction of the weight 24 is The inertial force of the piston 9, the piston pin 21, and the connecting rod 19 can be canceled and vibrations can be reduced. At this time, since the pulse chamber 31 of the vaporizer 30 communicates with the first air chamber 22 through the communication passage 33, the pressure of the pulse chamber 31 of the vaporizer 30 fluctuates due to the movement of the weight 24. A diaphragm 32 can supply fuel to the vaporizer 30.

  Next, before the piston 9 moves to the top dead center, the pressure in the combustion chamber 11 becomes maximum due to the combustion of the mixed gas, and the maximum pressure is generated in the piston 9. As shown in FIG. 6, when this maximum pressure is generated, the two air holes (communication portions) 36 communicating the first air chamber 22 and the crank chamber 18 that have been sealed by the piston 9 are opened. Along with the lowering of 24, the first air chamber 22 has the same pressure as the crank chamber 18 having a negative pressure. Therefore, the weight 24 held by the elastic body 25b rises at a stretch by the urging force of the elastic body 25b. By matching the timing at which the piston 9 descends due to the explosion of the mixed gas (the moment of the maximum pressure generated in the piston 9) and the timing at which the weight 24 suddenly rises, Can be offset by a simple rise, and vibration when the maximum pressure is generated can be reliably suppressed. The vent hole 36 is sealed by the piston 9 except when the piston 9 is located near the top dead center, and the weight 24 can be rapidly raised at the moment when the maximum pressure is applied to the piston 9, that is, The air chamber 22 and the crank chamber 18 are provided at a position where they communicate with each other.

  FIG. 7 is a diagram showing the relationship between the displacement of the weight 24 and the crank angle. The abscissa indicates the movement position (crank angle) of the piston 9 (weight 24), the ordinate indicates the displacement of the weight 24, the plus on the ordinate indicates the weight 24 is lowered, and the minus indicates the rise. BDC on the horizontal axis means the bottom dead center of the piston 9, and TDC means the top dead center. Immediately before the piston 9 moves to the top dead center (TDC), the pressure in the combustion chamber 11 becomes maximum (vibration is maximum) due to the combustion of the mixed gas, but as shown in FIG. By matching the timing of the 24 rapid rises, vibrations can be effectively suppressed.

  On the other hand, as the piston 9 rises, the crank chamber 18 and the second air chamber 23 become negative pressure, and the weight 24 descends. As the weight 24 descends, the first air chamber 22 (the first air chamber 22 on the left side of the piston 9) becomes negative pressure. Ventilation that connects the first air chamber 22 sealed with the piston 9 and the crank chamber 18 immediately before the piston 9 further moves up and moves to the top dead center (when the maximum pressure is generated in the piston 9). While the hole 36 is opened, the oil passage 28 (first communication) is communicated with the first air chamber 22 through the opening 28a as the weight 24 descends.

  When the weight 24 descends from the opening 28a, the oil passage 28 (opening 28a) is opened, and at the same time, the piston 9 is brought to a position immediately before the top dead center, thereby opening the vent hole 36. As the piston 9 is raised and the weight 24 is lowered, the air pressure in the first air chamber 22 and the crank chamber 18 is lower than the pressure in the oil chamber 27 (atmospheric pressure). Due to the pressure difference in the air chamber 22, the weight 24 rises rapidly, and the oil 26 is sucked into the first air chamber 22 from the oil chamber 27 through the oil passage 28. Mist. Further, when the oil 26 is drawn into the crank chamber 18 from the first air chamber 22, the oil 26 is further misted, and lubricating oil can be supplied into the crank chamber 18. Further, oil is also drawn into the first air chamber 22 located on the right side of the crank chamber 18 through the vent hole 36. Therefore, by supplying oil to the crank chamber 18 and the two first air chambers 22, oil can be supplied to the piston 9, the weight 24, etc., and lubrication can be performed effectively. Here, when the oil chamber 27 becomes negative pressure as the oil 26 is sucked and the weight 24 is raised and the opening 29a is opened, it is desirable to take in air from the breather passage 29.

  As described above, the center of gravity of the crankshaft 16 is provided at the center of the crank 20 in consideration of the equivalent mass for the rotational motion of the crank 20, the piston pin 21, and the connecting rod 19, that is, the inertia force in the Y direction is not generated. Thus, the inertia force in the moving direction (X direction) of the piston 9 can be canceled by the weight 24, and vibration in the rotational direction of the crank 20 can be reduced. In particular, the crank 20 has a circular shape and the center of gravity of the crankshaft 16 is provided at the center thereof, so that the inertia force in the X direction can be offset by the weight 24 while eliminating the inertia force in the Y direction. Furthermore, by providing the weights 24 on both sides of the piston 9, the moment generated by the movement of the piston 9 and the weight 24 can be suppressed, and vibration can be reliably reduced. Furthermore, by suddenly moving the weight 24 at the moment when the pressure applied to the piston 9 is maximized, that is, at the moment when the vibration is maximized, vibration can be effectively suppressed and oil can be supplied to the crank chamber 18 and the air chamber. Therefore, the piston 9 and the like can be suitably lubricated while suppressing vibration.

  Next, a second embodiment of the engine tool according to the present invention will be described with reference to FIGS. In addition, about 2nd Embodiment, a different point from 1st Embodiment is demonstrated.

  As shown in FIG. 10, the crankcase 18 a is formed with a crank chamber 18 and a second crank chamber 54 that is located below the crank chamber 18 and that can communicate with the crank chamber 18 via the communication portion 55. The second crank chamber 54 is provided with a seal member 50 that closes the communication portion 55 and a rotation shaft 51 that rotatably supports the seal member 50 in the second crank chamber 54. The seal member 50 is provided so as to rotate about the rotation shaft 51 due to pressure fluctuations in the crank chamber 18. The seal member 50 seals the communication portion 55 on one side of the seal member 50 with respect to the rotation shaft 51, and on the other side. One end is in contact with the weight 24 and the other end is in contact with a push bar 52 that is in contact with the seal member 50. The push rod 52 extends to the second air chamber 23 through a through hole 53 formed in the crankcase 18a. Since the through hole 53 is sealed by the push rod 52, the second air chamber 23 and the second crank chamber 54 do not communicate with each other.

  When the piston 9 is lowered from the state shown in FIG. 10, the state shown in FIGS. As the pressure in the crank chamber 18 rises, the seal member 50 rotates counterclockwise about the rotation shaft 51, the seal of the communication portion 55 by the seal member 50 is released, and the crank chamber 18 and the second crank The chamber 54 communicates, and the second crank chamber 54 reaches the same pressure as the crank chamber 18. When the push rod 52 is pushed upward by the rotation of the seal member 50, the weight 24 is raised by the push rod 52 and the elastic body 25 b, so that the vibration of the piston 9 can be canceled by the weight 24. FIG. 12 shows a state where the piston 9 has reached the bottom dead center.

  When the piston 9 rises from the state of FIG. 12, the state of FIG. 13 is obtained. As the piston 9 rises, the crank chamber 18 and the second crank chamber 54 become negative pressure, and the seal member 50 rotates clockwise around the rotation shaft 51 to seal the communication portion 55, and the push rod 52 is weight 24. Get away from. When the piston 9 is further raised from the state of FIG. 13, the state of FIG. 10 is obtained. In this state, since the vent hole 36 sealed by the piston 9 is opened, the first air chamber 22 becomes negative pressure, and the weight 24 rises at a stretch. By making the moment of inertia of the piston 24 and the moment of maximum pressure generated in the piston 9 the same, the inertia force generated by the downward movement of the piston 9 can be offset by the sudden increase of the weight 24. It is possible to reliably suppress vibration when the maximum pressure is generated. Further, at this time, since the oil 26 is supplied from the oil chamber 27 to the crank chamber 18 and the first air chamber 22, the piston and the like can be lubricated effectively. As in the first embodiment, a further vibration reduction effect can be obtained by providing dynamic vibration absorbers on both sides of the piston 9.

  Next, a third embodiment of the engine tool according to the present invention will be described with reference to FIGS. As shown in FIG. 14, the crankcase 18 a has a two-part configuration of an upper first crankcase 18 a 1 and a lower second crankcase 18 a 2. A first air chamber 22 and a vent hole 36 are formed in the first crankcase 18a1, and a cylinder 17 is attached. A second air chamber 23 and a dynamic vibration absorber are attached to the second crankcase 18a2. The dynamic vibration absorber includes a weight 64 and a leaf spring 60 that holds the weight 64. The leaf spring 60 passes through a through hole (not shown) provided in the leaf spring 60 and is screwed into the second crankcase 18a2. Is attached. The screws 61 and 62 are disposed in a space 63 formed by the first and second crankcases. At least one of the through holes of the screws 61 and 62 is a long hole extending in the longitudinal direction of the leaf spring 60 so that the leaf spring 60 can be deformed and moved when the weight 64 moves up and down. The weight 64 is formed with a holding portion 64 a that is held by the leaf spring 60, and has a shape corresponding to the deformation of the leaf spring 60. An oil passage 28, a breather passage 29, an oil chamber 27, and a communication passage 34 are formed in the second crankcase 18a2.

  Two dynamic vibration absorbers are provided in the crankcase 18a on both side surfaces of the piston 9, and operate in the same manner as in the first and second embodiments described above. When the piston 9 descends from the state of FIG. 14 to the state of FIG. 15 and further to the state of FIG. 16, the pressure in the crank chamber 18 rises and the pressure in the second air chamber 23 also rises via the communication passage 34. The weight 64 rises. When the piston 9 in FIG. 16 is in the bottom dead center state, the opening 29a of the breather passage 29 is opened, and the breather air passage 29 and the second air chamber 23 are communicated with each other through the opening 29a and leaked from the piston 9 due to combustion. Blow-by gas can be discharged to the outside.

  When the piston 9 rises from the state of FIG. 16 to the state of FIG. 17, the pressure in the crank chamber 18 becomes negative and the second air chamber 23 also becomes negative, so the weight 64 descends and seals the opening 29a. To do. When the piston 9 is further raised to the state shown in FIG. 14, the air hole 36 communicating with the first air chamber 22 (the air chamber on the left side of the cylinder) sealed with the piston 9 and the crank chamber 18 is opened. Along with the descending of 64, the first air chamber 22 has the same pressure as the crank chamber 18 in which the negative pressure is obtained. Therefore, the weight 64 rises at a stretch by the urging force of the leaf spring 60. By making the moment of inertia of the piston 64 suddenly increased and the moment of maximum pressure generated in the piston 9 the same, the inertia force generated by the downward movement of the piston 9 can be offset by the sudden increase of the weight 64, It is possible to reliably suppress vibration when the maximum pressure is generated. Further, the oil passage 28, the space 63, and the first air chamber 22 (left side of the piston 9) communicate with each other, and the first air chamber 22 and the crank chamber 18 are connected by the vent hole 36. Therefore, the oil 26 is vented by the pressure difference. 36 is supplied to the crank chamber 18 and the first air chamber 22 (on the right side of the piston 9), and lubrication can be suitably performed.

  As described above, according to the present invention, since the inertial force (vibration) generated by the reciprocating motion of the piston can be absorbed by the dynamic vibration absorber, the vibration transmitted to the operator can be suppressed as much as possible. Furthermore, by providing two dynamic vibration absorbers symmetrically with respect to the piston, the moment generated by the piston and the weight can be offset, and vibration can be further reduced. Furthermore, since the weight can be raised immediately before the top dead center of the piston having the largest inertia, the maximum pressure (inertia) generated when the piston moves can be effectively offset. Further, since the weight is not provided on the crank and the shape is circular, it is possible to prevent the occurrence of lateral vibration due to the movement of the weight. Furthermore, since oil can be supplied to the crank chamber and the air chamber by pressure fluctuation without using a pump or the like, the oil can be supplied with a simple configuration and lubrication can be suitably performed.

  1 is engine tool, 2 is engine, 3 is engine housing, 4 is rear handle, 5 is front handle, 6 is hand guard, 7 is saw chain, 8 is guide bar, 9 is piston, 10 is intake valve, 11 is combustion Chamber, 12 is an intake port, 13 is a spark plug, 14 is an exhaust valve, 15 is an exhaust port, 16 is a crankshaft, 17 is a cylinder, 18 is a crank chamber, 19 is a connecting rod, 20 is a crank, 21 is a piston pin, 22 Is a first air chamber, 23 is a second air chamber, 24 is a weight, 25 is an elastic body, 26 is oil, 27 is an oil chamber, 28 is a first passage (third communication passage), and 29 is a second passage (second passage). 2 communication paths), 30 is a vaporizer, 31 is a pulse chamber, 32 is a pump diaphragm, 33 is a communication path (fourth communication path), 34 is a communication path (first communication path), and 35 is a ventilation groove. 36 is a vent hole (communicating portion).

Claims (10)

A piston that reciprocates between top dead center and bottom dead center, a cylinder that guides the reciprocation of the piston, a crank connected to the piston, a crank chamber that houses the crank, and a reciprocation of the piston; A dynamic vibration absorber having a weight driven in opposite phase and an elastic body connected to the weight, and a housing portion for housing the dynamic vibration absorber,
An engine tool comprising a communication portion that communicates the crank chamber with the housing portion when the piston is located near top dead center. The accommodating portion is divided by the weight into a first air chamber located above the weight and a second air chamber located below the weight,
The engine tool according to claim 1, wherein the communication portion communicates with the first air chamber. A first communication path connecting the crank chamber and the second air chamber;
3. The engine tool according to claim 2, wherein the weight is reciprocated in the accommodating portion in accordance with pressure fluctuation in the crank chamber caused by reciprocation of the piston.   4. The second communication passage according to claim 3, further comprising a second communication passage that communicates the second air chamber with the outside when the weight is raised in the housing portion by moving the piston toward the bottom dead center side. Engine tool. An oil chamber for storing oil;
The engine according to any one of claims 2 to 4, further comprising a third communication passage that connects the oil chamber and the first air chamber when the piston is positioned near top dead center. tool.   The engine tool according to claim 5, wherein the third communication passage and the communication portion communicate with each other when the piston is positioned near the top dead center.   When a negative pressure is generated in the first air chamber due to the position of the weight, the oil in the oil chamber is sucked into the first air chamber via the third communication passage, and depending on the position of the piston The engine tool according to claim 6, wherein when the negative pressure in the crank chamber is generated, the oil is sucked into the crank chamber.   The first air chamber and the pulse chamber of the vaporizer are connected by a fourth communication path, and the pulse chamber performs pulse motion due to pressure fluctuation of the first air chamber caused by reciprocation of the weight. The engine tool according to any one of claims 2 to 7.   The engine tool according to any one of claims 1 to 8, wherein the crank has a circular shape and a crankshaft is disposed at a center of the crank.   The piston and the dynamic vibration absorber are arranged so as to be shifted in the radial direction of the piston with respect to the reciprocating direction of the piston, and two dynamic vibration absorbers are provided symmetrically with respect to the piston. The engine tool according to any one of claims 1 to 9.

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