JP2009275836A - Engine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine tool which reduces vibration to a worker by improving vibration control performance of the engine tool. <P>SOLUTION: The driving sources of the engine tool are a cylinder block and an engine. A piston which makes a reciprocating motion is housed in the cylinder block, and the engine converts the reciprocating motion of the piston to a rotary motion of a crankshaft. The engine tool has a dynamic vibration absorber which is constituted by a weight and an elastic body. The weight is constituted so that it makes a rectilinear motion, and the elastic body exerts an energizing force on the weight. The weight of the dynamic vibration absorber is driven by the pressure fluctuations in the cylinder block. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vibration damping technique in an engine tool using an engine in two cycles or four cycles, such as a chain saw, a blower, and a brush cutter.

  In a conventional engine tool, a piston descending in a cylinder generated by the combustion of a compressed air-fuel mixture is connected to a crank pin eccentric from the center of the crankshaft via a connecting rod. An inertia force is generated in the downward direction by the mass of the crankpin, the connecting rod, and the piston. Similarly, when the piston rises, an inertial force is generated in the upward direction by the mass of the crankpin, the connecting rod, and the piston. For this reason, the inertial force causes vibration and cancels out with crank unbalance, but even if the vertical vibration can be reduced, it may change to left and right vibration due to the unbalance. It cannot be offset. Therefore, the engine tool absorbs vibration using an elastic body such as rubber or a spring in order to attenuate the vibration while the vibration is transmitted to the part held by the operator.

  In addition, the dynamic vibration absorber exhibits a vibration damping action by driving a weight arranged in a state where an urging force by an elastic element is applied according to the magnitude of vibration input to the dynamic vibration absorber. That is, the dynamic vibration absorber has a passive characteristic that the amount of vibration suppression is determined according to the amount of vibration generated. Therefore, even if it is mounted on the engine tool, in the actual work, the operator strongly presses the engine tool against the work material and adjusts the rotation speed with the work material so that the work is performed on the work material side. The vibration amount input to the dynamic vibration absorber may be suppressed even though there is a high demand for vibration suppression because it has a considerable effect on the pressing force and the rotational speed of the engine tool.

  The structure described above does not have a structure for reducing vibrations in a wide range of frequencies in a dynamic vibration absorber when mounted on an elastic body that absorbs vibration or an engine tool. However, it is difficult to perform work for a long time because the operability is impaired.

An object of the present invention is to equip a dynamic vibration absorber that is relatively interlocked with the vertical movement of the piston and to improve the vibration damping performance of the engine tool, so that vibration transmitted to the operator can be reduced. It is to provide an engine tool capable of maximizing efficiency.

  Of the inventions disclosed in the present application, typical features will be described as follows.

According to one aspect of the present invention, a cylinder block that houses a reciprocating piston;
In an engine tool that uses an engine that converts reciprocating motion of a piston as rotational motion of a crankshaft as a drive source, a dynamic vibration absorber that includes a weight configured to be linearly movable and an elastic body that applies a biasing force to the weight; The weight of the dynamic vibration absorber is driven by the pressure fluctuation in the cylinder block.

  According to the first aspect of the present invention, the dynamic vibration absorber includes a weight configured to be linearly movable and an elastic body that applies an urging force to the weight, and the weight of the dynamic vibration absorber is within the cylinder block. Since driving is performed by pressure fluctuation, vibration transmitted to the worker is reduced, and operability and work efficiency can be maximized.

  According to the invention of claim 2, the linear motion of the weight is arranged on a parallel axis or coaxial with the reciprocating motion of the piston, and the piston defines the combustion chamber and the crank chamber with the piston sandwiched inside the cylinder block. The vibration absorber defines a first air chamber and a second air chamber with a weight interposed therebetween, and the air chamber of the dynamic vibration absorber into which pressure fluctuation is introduced is on the same side as the crankcase pressure fluctuation extraction side. When the weight is driven so as to face the piston, the vibration of the engine can be attenuated, and vibration and noise during work can be reduced.

  In particular, the weight of the dynamic vibration absorber is installed on the same axis in the reciprocating direction of the piston, so that the inertia force can be effectively canceled out.

  According to a third aspect of the invention, there is provided a diaphragm carburetor for supplying an air-fuel mixture to the engine, wherein the dynamic vibration absorber is disposed on the opposite side across the weight from the first air chamber and the first air chamber. Since a second air chamber is provided and the second air chamber communicates with the pump chamber of the vaporizer, the pump operation of the vaporizer can be performed as usual while using the existing pulse introduction path. Processing for providing the vibration absorber can be minimized.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

  An embodiment of an engine tool according to the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is a view for explaining the operation of an engine tool according to an embodiment of the present invention, and is a view showing when the crank chamber is in a negative pressure state. FIG. 2 is a view for explaining the operation of the engine tool according to the embodiment of the present invention, and is a view showing when the crank chamber is in a positive pressure state. FIGS. 3 to 6 are diagrams for explaining a general combustion stroke of a two-cycle engine which is an embodiment used in the engine tool according to the present embodiment.

  As shown in FIG. 1, an engine tool using a two-cycle engine is shown as an embodiment of the present invention. The engine includes a cylinder block 22, and the cylinder block 22 includes a cylinder head 20 and a crankcase 21. . The cylinder head 20 guides the cylindrical piston 1 so as to be movable up and down, and the piston 1 is rotatably supported by the crankcase 21 via the piston 1, the piston pin 17, the connecting rod 15, and the crank pin 16. It is connected to the crankshaft 7. In the cylinder block 22, the combustion chamber 3 is defined by the piston 1 and the cylinder head 20, and the crank chamber 2 is defined by the piston 1 and the crankcase 21. The combustion chamber 3 is provided with an ignition plug 8 on the upper wall, and an exhaust port 5a and a scavenging port 6 are provided on the side wall to supply an air-fuel mixture connected to the exhaust port 5b and the crank chamber 2 for discharging combustion gas, respectively. Connected to the port. An intake port 4a is opened in the crank chamber 16 and is connected to an intake port 4b communicating with outside air. The intake port 4 b introduces air from the outside air, and is mixed with fuel by a diaphragm type carburetor 13 provided in the middle of the intake port 4 b to generate an air-fuel mixture that is sent to the combustion chamber 3.

  The crank chamber 2 communicates with the dynamic vibration absorber 19 through a pulse path 23a. The dynamic vibration absorber 19 is arranged in such a direction that the weight 12 linearly moves on a parallel axis with the reciprocating motion of the piston, and the weight 12 is sandwiched non-integrally from both sides on the movement axis of the weight 12. Energized. The dynamic vibration absorber 19 defines a first air chamber 9 and a second air chamber 10 with a weight 12, and the first air chamber 9 communicates with the crank chamber 2. The intake port 4 b is provided with a diaphragm type carburetor 13 that supplies an air-fuel mixture to the combustion chamber 3. The carburetor 13 is connected to a fuel tank via a fuel supply path (not shown), and the pulse chamber 14 in the carburetor 13 is provided with a pump diaphragm 18 that oscillates to suck up fuel from the fuel tank. The pulse chamber 14 communicates with the second air chamber 10 via a pulse path 23 b of the dynamic vibration absorber 19, and the pump diaphragm 18 can be vibrated by the pressure variation of the second air chamber 10.

Next, the weight of the dynamic vibration absorber 19 includes the weight 12 configured to be linearly movable as described above, and the dynamic vibration absorber 19 including the elastic bodies 11a and 11b that apply an urging force to the weight 12. The operation of the engine 12 driven by pressure fluctuation in the cylinder block will be described.
As shown in FIG. 3, when the piston 1 rises from the bottom dead center, the crank chamber 2 becomes negative pressure as the volume of the crank chamber 2 increases, while the air-fuel mixture is compressed in the combustion chamber 3 as the volume decreases. Is done. Further, when the piston 1 passes through the intake port 4b and opens, the air-fuel mixture is sucked into the crank chamber 2 due to a pressure difference from the atmosphere. Then, as shown in FIG. 4, the piston 1 descends after passing through the top dead center, whereby the intake port 4 b is closed, and the air-fuel mixture compressed in the combustion chamber 3 is burned by the spark of the spark plug 8 and the piston 1 As shown in FIG. 5, the lowering is accelerated, and the exhaust port 5 b is opened by the lowering of the piston 1, the burned gas starts to be discharged, and the air-fuel mixture in the crank chamber 2 starts to be compressed. Further, as shown in FIG. 6, the compressed air-fuel mixture is drawn into the combustion chamber 3 by opening the scavenging port 6 when the piston 1 descends. The output of the crankshaft 7 is repeated by repeating the steps of the air-fuel mixture compression, combustion, exhaust, scavenging, and air-fuel mixture suction and scavenging performed in the combustion chamber 3 using the pressure difference from the atmospheric pressure in the crank chamber 2. A working device (not shown) connected to the shaft is driven.

  In one embodiment according to the present invention, as shown in FIG. 1, in the step of exhausting the burned gas in the combustion chamber 3, the mixture in the crank chamber 2 is compressed by the lowering of the piston 1, and the crank chamber 2 and the pulse path are compressed. The air or air-fuel mixture in the first air chamber 9 of the dynamic vibration absorber 19 communicated with the air compressor 23a is also compressed. Furthermore, since the air-fuel mixture in the first air chamber 9 is compressed, the atmospheric pressure in the first air chamber 9 becomes larger than that in the second air chamber 10, so that the piston 1 and the weight 12 held by the elastic bodies 11a and 11b On the parallel axis, the weight 12 moves in the direction opposite to the reciprocating motion of the piston 1 in the direction in which the elastic body 11b holding the moving direction of the weight 12 is compressed. Is driven. Further, as the weight 12 moves, the air or air-fuel mixture in the second air chamber 10 is compressed, causing a pressure fluctuation in the pulse chamber 14 of the carburetor 13 communicating with the second air chamber 10 via the pulse path 23b. And the pump diaphragm 18 is vibrated. By the pump operation of the pump diaphragm 18, fuel is sucked up from the fuel tank via a fuel supply path (not shown), and the fuel is supplied into the carburetor 13.

  Similarly, before the piston 1 passes through the bottom dead center, the scavenging port 6 is opened, the air-fuel mixture compressed by the lowering of the piston 1 enters the combustion chamber 3, and the pressure drop in the crank chamber 2 starts. After passing through the bottom dead center, the piston 1 starts to rise, and as shown in FIG. 2, when the scavenging port 6 is completely closed, the atmospheric pressure in the crank chamber 2 becomes negative as the piston 1 rises. Go. For this reason, the air-fuel mixture is sucked into the crank chamber 2 and at the same time, the atmospheric pressure in the first air chamber 9 communicating with the crank chamber decreases from the second air chamber 10. Since the pressure in the air chamber 9 is reduced and the weight 12 moves in the direction opposite to the moving direction of the piston 1, the elastic body 11a holding the moving direction of the weight 12 is compressed. In addition, since the pressure of the second air chamber 10 decreases due to the movement of the weight 12, the pressure fluctuation of the pulse chamber 14 of the carburetor 13 is generated, and the fuel is supplied into the carburetor 13.

  Next, the effect of using the dynamic vibration absorber according to the present embodiment will be described. The weight 12 moves in the direction opposite to the operation direction of the piston 1 while the elastic body 11b gripped in the movement direction of the weight 12 is compressed, so that the piston 1, piston pin 17, The inertial forces of the connecting rod 15 and the crankpin 16 can be canceled out, and vibration can be reduced.

  In addition, the linear motion of the weight is located on the axis parallel to the reciprocating motion of the piston. Since the air chamber of the dynamic vibration absorber that defines the first air chamber and the second air chamber and the pressure fluctuation is introduced is on the same side as the crankcase pressure fluctuation extraction side, the weight is opposed to the piston. The vibration of the engine can be attenuated and the vibration and noise during work can be reduced. In the present embodiment, the operation axis of the weight 12 is on the parallel axis of the piston, but the present invention is not limited to this and may be arranged coaxially or substantially coaxially. According to this, since the weight operates directly on the axis of the reciprocating motion of the piston, it is possible to effectively cancel the inertia force.

  In addition, a diaphragm carburetor for supplying an air-fuel mixture to the engine is provided, and the dynamic vibration absorber has a first air chamber communicating with the crankcase, and a second air chamber on the opposite side across the weight from the first air chamber. At the same time, the second air chamber communicates with the pump chamber of the carburetor, so that the pump operation of the carburetor can be performed as usual while using the existing pulse introduction path, thereby providing a dynamic vibration absorber. Can be minimized.

  As mentioned above, although demonstrated based on embodiment which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning.

For example, in the present embodiment, the engine is described using a two-cycle engine. However, any engine working machine using the engine as a drive source is effective.

It is a figure for demonstrating operation | movement of the engine tool which concerns on embodiment of this invention, and is a longitudinal cross-sectional view which shows the time of a crank chamber being a negative pressure state. It is a figure for demonstrating operation | movement of the engine tool which concerns on embodiment of this invention, and is a longitudinal cross-sectional view which shows the time of a crank chamber being a positive pressure state. It is a longitudinal cross-sectional view which shows the compression process of a general 2 cycle engine. It is a longitudinal cross-sectional view which shows the combustion process of a general 2 cycle engine. It is a longitudinal cross-sectional view which shows the exhaust process of a general 2 cycle engine. It is a longitudinal cross-sectional view which shows the scavenging process of a general 2 cycle engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Crank chamber 3 Combustion chamber 4a Intake port 4b Intake port 5a Exhaust port 5b Exhaust port 6 Scavenging port 7 Crankshaft 8 Spark plug 9 1st air chamber 10 2nd air chamber 11a, 11b Elastic body 12 Weight 13 Vaporizer 14 Pulse chamber 15 Connecting rod 16 Crank pin 17 Piston pin 18 Pump / diaphragm 19 Dynamic vibration absorber 20 Cylinder head 21 Crank case 22 Cylinder blocks 23a, 23b Pulse path

Claims (3)

A cylinder block containing a reciprocating piston;
In an engine tool whose driving source is an engine that converts the reciprocating motion of the piston into the rotational motion of a crankshaft,
A dynamic vibration absorber including a weight configured to be linearly movable and an elastic body that applies an urging force to the weight, and the weight of the dynamic vibration absorber is driven by pressure fluctuation in the cylinder block An engine tool characterized by   The weight is arranged to linearly move on a parallel axis or on the same axis as the reciprocating motion of the piston, the piston defines a combustion chamber and a crank chamber with the piston sandwiched inside the cylinder block, and the dynamic vibration absorption The chamber defines a first air chamber and a second air chamber across the weight, and the air chamber of the dynamic vibration absorber to which pressure fluctuation is introduced is on the same side as the crankcase pressure fluctuation take-out side. The engine tool according to claim 1. A carburetor having a diaphragm type pulse chamber for supplying an air-fuel mixture to the engine, wherein the dynamic vibration absorber is located on a side opposite to the first air chamber with a weight from the first air chamber; 3. The engine tool according to claim 1, further comprising two air chambers, wherein the second air chamber communicates with the pulse chamber.

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