JP6389416B2 - Chain saw - Google Patents

Description

  The present invention relates to a chain saw having an oil tank.

  In a chain saw used for cutting trees, board materials, etc., since the saw chain rotates at high speed around the outer periphery of the guide bar, it is necessary to supply lubricating oil to the sliding portion between the guide bar and the saw chain. For this reason, the chain saw is provided with an oil pump that sucks oil in the oil tank and supplies the sucked oil to the sliding portion between the guide bar and the saw chain.

If the oil in the oil tank is sucked out by the oil pump and the pressure in the oil tank becomes negative, the oil pump cannot suck the oil and it is difficult to remove the cap from the oil supply port of the oil tank.
In view of this, some conventional chain saw oil tanks are provided with a one-way valve that only allows flow in the direction of suction from the external space (see, for example, Patent Document 1).
In this configuration, as the oil in the oil tank decreases, air flows from the external space into the oil tank, so that the oil tank can be prevented from becoming negative pressure.

International Publication No. 2014/070052 Pamphlet

  In the conventional chain saw described above, it is possible to prevent the inside of the oil tank from becoming negative pressure when the oil pump is driven. However, when the oil thermally expands due to heat from the engine or the exhaust muffler, the pressure in the oil tank increases. . At this time, since the one-way valve of the oil tank only allows the flow in the direction of suction from the external space, the oil tank has a high pressure. Then, when the drive of the chain saw is stopped and the oil discharge from the oil pump is stopped, the pressure in the oil tank becomes higher, and the oil leaks from the discharge port of the oil pump due to the pressure in the oil tank.

  Some conventional chain saws are provided with a two-way valve in the breather of the oil tank that allows the outer space to flow in the direction of discharge and suction. In this configuration, the oil tank does not leak due to the high pressure inside the oil tank, but when the amount of oil stored in the oil tank is large, if the pressure in the oil tank rises due to temperature rise, Oil may leak from the breather.

  Further, the chain saw may be tilted or inverted up and down during use or transportation. In the configuration using the two-way valve, oil may leak from the breather directly formed in the oil tank.

  The present invention solves the above-described problems, can prevent high pressure and negative pressure in the oil tank, and can prevent oil from leaking due to thermal expansion of oil and air in the oil tank. It is an issue to provide.

In order to solve the above problems, a chain saw according to a first aspect of the present invention includes a chain saw body, a guide bar that is detachably attached to the chain saw body, and a saw chain that is wound around an outer peripheral portion of the guide bar. The chain saw body includes an oil tank, an oil pump that supplies oil stored in the oil tank to a sliding portion between the guide bar and the saw chain, and an attitude of the chain saw body during normal use or storage A first expansion chamber disposed above the oil tank, and a second expansion chamber disposed above the first expansion chamber in the posture of the chain saw body during normal use or storage. Is provided. The oil tank is communicated with the first expansion chamber through the first channel, the first expansion chamber is in communication with the said second expansion chamber through the second channel, the Second expansion chamber, said A vent hole communicating with the external space of the chain saw body is formed. The ventilation hole is provided with a filter having air permeability, and is configured to suck and exhaust air between the second expansion chamber and the external space through the filter.
In order to solve the above problems, a chain saw according to a second aspect of the present invention includes a chain saw body, a guide bar that is detachable from the chain saw body, and a saw chain that is wound around an outer peripheral portion of the guide bar. The chain saw body includes an engine that drives the saw chain, an oil tank, an oil pump that supplies oil stored in the oil tank to a sliding portion between the guide bar and the saw chain, and a normal use or In the posture of the chain saw body during storage, the first expansion chamber is disposed above the oil tank, and in the posture of the chain saw body during normal use or storage, it is disposed above the first expansion chamber. And a second expansion chamber. The oil tank communicates with the first expansion chamber through a first flow path, and the first expansion chamber communicates with the second expansion chamber through a second flow path. A vent hole communicating with the external space of the chain saw body is formed. The crankcase of the engine has left and right case members, the oil tank and the first expansion chamber are formed by being divided into the two case members, and the first flow path is a connecting portion of the two case members Is formed.

In this configuration, since the inside of the oil tank communicates with the external space through the expansion chamber and the flow path, the inside of the oil tank can be prevented from becoming a high pressure and a negative pressure.
As described above, in the chain saw according to the present invention, it is possible to prevent the oil tank from becoming a high pressure. Therefore, after the chain saw is stopped and the oil pump stops discharging, the oil pump discharges from the discharge port of the oil pump. Oil can be prevented from leaking.

  In addition, when the oil or air in the oil tank is thermally expanded, or when the chain saw is tilted and turned upside down, the oil in the oil tank flows into the first expansion chamber, but has a vent hole. The second expansion chamber is spaced apart from the oil tank in the height direction via the first expansion chamber, and it is difficult for oil to flow from the oil tank to the second expansion chamber. Leakage can be prevented.

  In the chain saw of the present invention, the first expansion chamber and the second expansion chamber are disposed above the oil tank. Therefore, when the chain saw is placed in a normal use or storage position (position in which both expansion chambers are disposed above the oil tank), the oil that has flowed into the expansion chamber also flows down the flow path. Therefore, the oil can be prevented from leaking outside.

  Further, in the chain saw of the present invention, the oil tank and the two expansion chambers can be integrally provided on a member such as an engine crankcase, so that the chain saw body can be added to the chain saw body without adding new parts to the conventional chain saw. By forming the two expansion chambers, oil can be prevented from leaking.

  In the present invention, the configuration of the chain saw other than the oil tank, the two expansion chambers, and the two flow paths is not limited. For example, the present invention can be applied to an engine-type chain saw in which the chain saw body includes an engine that drives the saw chain. Further, the present invention can also be applied to an electric chain saw in which the chain saw body includes an electric motor that drives the saw chain.

  In the above-described chain saw, when a filter having air permeability is provided in the vent hole and the air is sucked and exhausted between the second expansion chamber and the external space through the filter, It is possible to surely prevent dust and dust from entering.

In the above-described chain saw, it is preferable that the oil storage amount of the first expansion chamber is 5% or more of the oil storage amount of the oil tank. The oil storage amount is the maximum oil amount that can be stored in the first expansion chamber or the oil tank.
In this way, by setting the amount of oil stored in the first expansion chamber, all oil that has flowed out of the oil tank can be removed even when the oil is thermally expanded while the oil is filled in the oil tank. It can be stored in the first expansion chamber.

  In the above-described chain saw, when at least one of the first flow path and the second flow path is configured by a tubular member such as a pipe or a hose, the oil tank and the two expansion chambers are further spaced apart from each other. be able to. Therefore, the degree of freedom in the layout of the oil tank and both expansion chambers can be increased, and the distance from the oil tank to the second expansion chamber can be increased.

  The above-described chain saw includes an engine in which the chain saw body drives the saw chain, and an exhaust muffler coupled to the engine. In this case, it is desirable to arrange the oil tank and at least one of the first expansion chamber and the second expansion chamber between the engine drive unit and the exhaust muffler.

In this configuration, the heat of the exhaust muffler can be blocked by the oil in the oil tank and the air in the expansion chamber, so that the heat of the exhaust muffler can be made difficult to be transmitted to the components of the drive unit and the vaporizer.
In addition, since the oil tank and the expansion chamber are arranged by effectively using the space between the engine drive unit and the exhaust muffler, it is possible to prevent the chain saw body from becoming large.
The oil tank and the expansion chamber may be formed on the wall of the crankcase that constitutes the engine, or may be provided separately from the crankcase.

  As the above-mentioned chain saw, there is a chain saw in which the chain saw body includes an engine for driving the saw chain, and a crankcase of the engine is composed of left and right case members. In this case, the oil tank and the first expansion chamber are divided into the two case members, and the first flow path is formed at the connecting portion of the two case members, so that the first configuration can be simplified. One flow path can be formed in the crankcase. Therefore, it is advantageous from the viewpoint of assembly of the chain saw and the number of parts.

  In the above-described configuration, the first expansion chamber is formed on both the left and right sides of the first flow path, and the oil in the first expansion chamber accumulates on the left and right sides of the first expansion chamber even when the chain saw is inclined. Therefore, it is difficult for oil to flow from the first expansion chamber to the second expansion chamber.

  In the chain saw of the present invention, the oil tank communicates with the external space through the two expansion chambers, so that it is possible to prevent the oil tank from becoming high pressure and negative pressure and to prevent oil from leaking. Can do.

It is the side view which showed the chain saw which concerns on embodiment of this invention. It is the side view which showed the engine and exhaust muffler which concern on embodiment of this invention. It is AA sectional drawing of FIG. It is the figure which showed other embodiment of this invention, and is a perspective view at the time of comprising a flow path with the tubular member.

Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the chain saw 1 of the present embodiment includes a chain saw body 10, a guide bar 20 that is detachable from the chain saw body 10, and a saw chain 30 that is wound around the outer periphery of the guide bar 20. Yes.

  The chain saw body 10 includes an engine 40 for rotating the saw chain 30, an exhaust muffler 50 through which exhaust gas discharged from the engine 40 passes, and an oil pump that supplies oil to a sliding portion between the guide bar 20 and the saw chain 30. 60 (see FIG. 3).

  The chain saw 1 of the present embodiment has the same configuration as a conventionally known chain saw except for the configuration of an oil tank 70 and expansion chambers 71 and 72 (see FIG. 2), which will be described later. Description is omitted. Moreover, in the following description, the front indicates the tip side of the guide bar 20 (left side in FIG. 1).

  As shown in FIG. 2, the engine 40 is an internal combustion engine having a cylinder block 41 and a crankcase 42. As shown in FIG. 3, the crankcase 42 is divided into left and right case members 42a and 42a, and a gasket 42b is sandwiched between the case members 42a and 42a.

  As shown in FIG. 2, the exhaust muffler 50 is a box-like silencer, and is disposed in front of the cylinder block 41 and above the front portion of the crankcase 42. The exhaust muffler 50 is connected to the exhaust port of the cylinder block 41.

  Further, as shown in FIG. 1, the chain saw body 10 is provided with a front handle 11 that is gripped when the chain saw 1 is carried and a throttle lever 12 for adjusting the output of the engine 40.

  As shown in FIG. 3, the oil pump 60 is provided at the front portion of the right side portion of the chain saw body 10. The drive shaft of the oil pump 60 is connected to the crankshaft of the engine 40, and the oil pump 60 is driven by the driving force of the engine 40.

The oil pump 60 sucks oil in an oil tank 70 which will be described later, and from an outlet (not shown) provided on the guide bar 20 side, an oil groove (not shown) of the guide bar 20 (see FIG. 1). Supply oil to
And it is comprised so that oil may be supplied to the sliding part of the guide bar 20 and the saw chain 30 by oil flowing out to the outer surface from the oil groove of the guide bar 20 shown in FIG.

The guide bar 20 is a plate-like member extended in the front-rear direction, and the rear part is attached to the front part of the chain saw body 10.
The saw chain 30 is an annular cutting member wound around the outer periphery of the guide bar 20, and the rear portion of the saw chain 30 is wound around a sprocket (not shown) of the engine 40, and the saw chain 30 is driven by the driving force of the engine 40. It is driven to rotate along the outer periphery of the guide bar 20.

As shown in FIG. 2, an oil tank 70, a first expansion chamber 71, and a second expansion chamber 72 are formed in the crankcase 42 of the engine 40.
The oil tank 70 and the two expansion chambers 71 and 72 are formed in the wall portion on the exhaust muffler 50 side in the crankcase 42.
The oil tank 70 is formed below the crankcase 42, a first expansion chamber 71 is formed above the oil tank 70, and a second expansion chamber 72 is formed above the first expansion chamber 71.
The oil tank 70 and the expansion chambers 71 and 72 are disposed between the drive unit of the engine 40 and the exhaust muffler 50.
In addition, the drive part of the engine 40 is an internal structure of the engine 40, and is a part constituted by components (for example, a piston, a connecting rod, a crankshaft, and the like) that are driven in the engine 40.

The oil tank 70 is a part that stores oil supplied to a sliding portion between the guide bar 20 and the saw chain 30. As shown in FIG. 3, the oil tank 70 is divided into both case members 42a and 42a. The left and right parts of the oil tank 70 are formed in substantially the same size.
A discharge pipe 70 a communicating with the suction port of the oil pump 60 is provided at the bottom of the oil tank 70. Then, the oil in the oil tank 70 is sucked out from the discharge pipe 70 a by the oil pump 60, and the oil is supplied to the sliding portion between the guide bar 20 and the saw chain 30.

The first expansion chamber 71 is a part that stores oil that has flowed out of the oil tank 70. The first expansion chamber 71 is formed by being divided into both case members 42a and 42a. The left and right portions of the first expansion chamber 71 are formed to have substantially the same size.
The oil storage amount in the first expansion chamber 71 is preferably set to 5% or more of the oil storage amount in the oil tank 70. In the present embodiment, the amount of oil stored in the first expansion chamber 71 is set to 7% of the amount of oil stored in the oil tank 70.

The oil tank 70 and the first expansion chamber 71 communicate with each other through the first flow path 81.
The first flow path 81 is formed at a connecting portion between the case members 42a and 42a. Specifically, it is formed by a gap between the joint surfaces of both case members 42a, 42a.

In the present embodiment, the gasket 42b sandwiched between the two case members 42a and 42a is not provided in a portion that becomes the first flow path 81, so that the first flow path 81 and the joint surface of the two case members 42a and 42a are connected to each other. A gap is formed.
In addition, you may form the 1st flow path 81 by forming a recessed part in a part of joining surface of the case member 42a.

  The first flow path 81 of the present embodiment is a slit-like groove that is elongated in the front-rear direction, and the width in the left-right direction is about 0.2 mm. Thus, by forming the width of the first flow path 81 narrow, air passes through the first flow path 81, but viscous oil is difficult to circulate. Thereby, the pressure in the oil tank 70 is quickly adjusted, and the oil in the oil tank 70 hardly flows out to the outside through the first expansion chamber 71 and the second expansion chamber 72.

The first flow path 81 is formed from the center in the left-right direction of the oil tank 70 to the center in the left-right direction of the first expansion chamber 71. Therefore, the oil tank 70 and the first expansion chamber 71 are formed on the left and right sides of the first flow path 81.
That is, the width in the left-right direction of the first flow path 81 is significantly narrower than that of the oil tank 70 and the first expansion chamber 71 having substantially the same width as the width in the left-right direction of the chain saw body 10 (about 200 mm in this embodiment). ing.

The second expansion chamber 72 is divided into both case members 42a and 42a. The left and right portions of the second expansion chamber 72 are formed to have substantially the same size.
The first expansion chamber 71 and the second expansion chamber 72 communicate with each other through the second flow path 82.
The 2nd flow path 82 is formed in the connection part of both case members 42a and 42a. Specifically, it is formed by a gap between the joint surfaces of both case members 42a, 42a.

In the present embodiment, the gasket 42b that is sandwiched between the case members 42a and 42a is not provided in a portion that becomes the second channel 82, so that the second channel is provided between the joint surfaces of the case members 42a and 42a. A gap to be 82 is formed.
In addition, you may form the 2nd flow path 82 by forming a recessed part in a part of joining surface of the case member 42a.

Similar to the first flow path 81, the second flow path 82 of the present embodiment is a slit-like groove that is elongated in the front-rear direction, and the width in the left-right direction is about 0.2 mm.
The second flow path 82 is formed from the center portion in the left-right direction of the first extension chamber 71 to the center portion in the left-right direction of the second extension chamber 72. Therefore, the first expansion chamber 71 and the second expansion chamber 72 are formed on the left and right sides of the second flow path 82.
That is, the width in the left-right direction of the second flow path 82 is significantly narrower than the width in the left-right direction of the oil tank 70 and the first expansion chamber 71.

  A vent hole 83 communicating with the external space is formed in the right side wall portion of the second expansion chamber 72. The ventilation hole 83 is a cylindrical hole, and opens to the side surface (right side surface) of the crankcase 42 on the guide bar 20 side.

A filter 84 is inserted into the ventilation hole 83. The filter 84 is a member having air permeability such as sintered metal or sponge. The filter 84 can be ventilated in two directions, and can be sucked and exhausted between the external space and the second expansion chamber 72 through the filter 84.
Further, by providing the filter 84 in the vent hole 83, it is possible to reliably prevent dust and dirt from entering the expansion chambers 71 and 72 and the oil tank 70 from the external space.

In the chain saw 1 as described above, as shown in FIG. 3, the oil tank 70 communicates with the external space through the two expansion chambers 71 and 72 and the two flow paths 81 and 82, so that the oil tank 70 has a high pressure and A negative pressure can be prevented.
In this way, in the chain saw 1, it is possible to prevent the inside of the oil tank 70 from becoming a high pressure. Therefore, after the drive of the chain saw 1 stops and the oil discharge from the oil pump 60 stops, the oil pump 60 discharges. Oil can be prevented from leaking from the outlet.

Further, when the oil or air in the oil tank is thermally expanded, or when the chain saw 1 is tilted and turned upside down, the oil in the oil tank 70 flows into the first expansion chamber 71. The second expansion chamber 72 including 83 is spaced apart from the oil tank 70 in the height direction via the first expansion chamber 71, and has a structure in which oil does not easily flow into the second expansion chamber 72 from the oil tank 70. ing.
Since the first expansion chambers 71 are formed on both the left and right sides of the first flow path 81, the oil is collected on the left and right sides of the first expansion chamber 71 even when the chain saw 1 is inclined.
Further, in the chain saw 1, both the expansion chambers 71 and 72 are disposed above the oil tank 70, and the widths of the first flow path 81 and the second flow path 82 are narrow.
Accordingly, in the chain saw 1, it is difficult for oil to flow into the second expansion chamber 72 from the oil tank 70, and therefore oil can be prevented from leaking to the outside from the vent hole 83 of the second expansion chamber 72.

  Moreover, in the chain saw 1, since the oil storage amount of the first expansion chamber 71 is set to 5% or more of the oil storage amount of the oil tank 70, the oil is thermally expanded in a state where the oil is filled in the oil tank 70. Even in this case, all of the oil that has flowed out of the oil tank 70 can be stored in the first expansion chamber 71.

In the chain saw 1, the oil tank 70 and the expansion chambers 71 and 72 can be integrally provided in the crankcase 42 of the engine 40, so that oil can be added without adding new parts to the conventional chain saw. Leakage can be prevented.
Further, in the chain saw 1, both the flow paths 81 and 82 can be formed in the crankcase 42 with a simpler structure by forming the both flow paths 81 and 82 at the connecting portions of the case members 42a and 42a. . Therefore, it is advantageous in terms of the assemblability of the chain saw 1 and the number of parts.

  In the chain saw 1, a first expansion chamber 71 is disposed above the oil tank 70. Therefore, when the chain saw 1 is disposed in a normal use or storage posture (an posture in which the two expansion chambers 71 and 72 are disposed above the oil tank 70), the chain saw 1 flows into the first expansion chamber 71. Since oil flows down the first flow path 81 and is returned to the oil tank 70, it is possible to prevent oil from leaking to the outside.

  In the chain saw 1, as shown in FIG. 2, the oil tank 70 and the two expansion chambers 71 and 72 are disposed between the drive unit of the engine 40 and the exhaust muffler 50. As a result, the heat of the exhaust muffler 50 can be blocked by the oil in the oil tank 70 and the air in the expansion chambers 71 and 72, so that the heat of the exhaust muffler 50 is prevented from being transmitted to the components of the drive unit and the vaporizer. be able to.

  Further, in the chain saw 1, since the oil tank 70 and the two expansion chambers 71 and 72 are arranged by effectively using the space between the drive unit of the engine 40 and the exhaust muffler 50, the chain saw body 10 (FIG. 1). Reference) can be prevented from becoming large.

The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.
In the chain saw 1 of the present embodiment, as shown in FIG. 3, both flow paths 81 and 82 are formed at the connecting portions of both case members 42 a and 42 a, but the portions where both flow paths 81 and 82 are formed are limited. Is not to be done.
As shown in FIG. 4, when the first flow path 81 and the second flow path 82 are configured by tubular members such as pipes and hoses, the height positions of the oil tank 70 and the expansion chambers 71 and 72 are further separated. Can be arranged. Therefore, the degree of freedom in the layout of the oil tank 70 and the two expansion chambers 71 and 72 can be increased, and the distance from the oil tank 70 to the second expansion chamber 72 can be increased.
In FIG. 4, both the first flow path 81 and the second flow path 82 are configured by tubular members, but only one of the first flow path 81 and the second flow path 82 is configured by a tubular member. Also good.

Further, in the chain saw 1 of the present embodiment, as shown in FIG. 2, the oil tank 70 and both expansion chambers 71 and 72 are formed in the crankcase 42. However, the oil tank 70 and both expansion chambers 71 and 72 are connected to the engine. You may form in 40 other site | parts.
Furthermore, the oil tank 70 and the two expansion chambers 71 and 72 may be provided separately from the crankcase 42. In this configuration, the oil tank 70 and the two expansion chambers 71 and 72 can be arranged at the front part or the rear part of the chain saw body 10 according to the internal structure of the chain saw 1.

  Further, in the chain saw 1 of the present embodiment, both the expansion chambers 71 and 72 are disposed between the drive unit of the engine 40 and the exhaust muffler 50, but only one of the both expansion chambers 71 and 72 is driven by the engine 40. May be disposed between the exhaust section and the exhaust muffler 50.

  Further, in the chain saw 1 of the present embodiment, the chain saw body 10 is provided with one first extension chamber 71 and one second extension chamber 72. However, the first extension chamber 71 and the second extension chamber 72 are divided into a plurality of sections. You may provide in a location. In that case, what is necessary is just to set so that the sum total of the oil storage amount of the some 1st expansion chamber 71 may be 5% or more of the oil storage amount of the oil tank 70. FIG.

  In the present embodiment, the engine-type chain saw 1 is described in which the chain saw body 10 includes the engine 40 that drives the saw chain 30. However, the chain saw according to the present invention includes an oil tank, both expansion chambers, and both flow paths. The configuration other than is not limited. Therefore, the present invention can also be applied to an electric chain saw in which the chain saw body includes an electric motor that drives the saw chain.

1 Chain saw 10 Chain saw body 20 Guide bar 30 Saw chain 40 Engine 41 Cylinder block 42 Crankcase 42a Case member 50 Exhaust muffler 60 Oil pump 61 Discharge port 70 Oil tank 71 First expansion chamber 72 Second expansion chamber 81 First flow path 82 Second Flow path 83 Vent hole 84 Filter

Claims (6)

The chain saw body,
A guide bar detachable from the chain saw body;
A saw chain wound around the outer periphery of the guide bar,
In the chain saw body,
An oil tank,
An oil pump for supplying oil stored in the oil tank to a sliding portion between the guide bar and the saw chain;
A first expansion chamber disposed above the oil tank in the posture of the chain saw body during normal use or storage ;
In the posture of the chain saw body during normal use or storage, a second expansion chamber disposed above the first expansion chamber is provided,
The oil tank communicates with the first expansion chamber through a first flow path,
The first expansion chamber communicates with the second expansion chamber through a second flow path,
In the second expansion chamber, a vent hole communicating with the external space of the chain saw body is formed ,
The vent hole is provided with a breathable filter,
A chain saw configured to suck and exhaust air between the second expansion chamber and the external space through the filter . The oil storage amount of the first expansion chamber, chain saw according to claim 1, wherein at least 5% of the oil reservoir of the oil tank. The chain saw according to claim 1 or 2 , wherein at least one of the first flow path and the second flow path is configured by a tubular member. The chain saw body is
An engine for driving the saw chain;
An exhaust muffler coupled to the engine,
Claim from claim 1, wherein said oil tank, and at least one of the first expansion chamber and the second expansion chamber, that is disposed between the exhaust muffler and the driving part of the engine the chain saw according to any one of 3. The chain saw body,
A guide bar detachable from the chain saw body;
A saw chain wound around the outer periphery of the guide bar,
In the chain saw body,
An engine for driving the saw chain;
An oil tank,
An oil pump for supplying oil stored in the oil tank to a sliding portion between the guide bar and the saw chain;
A first expansion chamber disposed above the oil tank in the posture of the chain saw body during normal use or storage ;
In the posture of the chain saw body during normal use or storage, a second expansion chamber disposed above the first expansion chamber is provided,
The oil tank communicates with the first expansion chamber through a first flow path,
The first expansion chamber communicates with the second expansion chamber through a second flow path,
In the second expansion chamber, a vent hole communicating with the external space of the chain saw body is formed ,
The crankcase of the engine has left and right case members,
The oil tank and the first expansion chamber are formed by being divided into both case members,
The chain saw, wherein the first flow path is formed in a connecting portion between the two case members . The chain saw body is
The chain saw according to any one of claims 1 to 3 , further comprising an electric motor that drives the saw chain.

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