JP2001047403A - Motor-driven chain saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a significant braking action by constituting an inertially operated brake of a brake release member to be press-bond to a brake band by means of a spring force within a region of a brake drum and providing the brake release member in such a way that it is separated from the brake band resisting the spring force by manually operating the member. SOLUTION: The motor-driven chain saw comprises a brake drum 16 arranged in a chain wheel drive force transmission system for driving a saw blade chain and a brake band 17 wound around the brake drum 16. In addition, the chain saw is equipped with a kick back-type brake 18 which can be released through a hand guard U member 14 for suddenly stopping the saw blade chain and an inertially operated brake 19 which works when a manually operated member 28 is released during starting of the chain saw. The inertially operated brake 19 is equipped with a brake release member 30 which is press-bonded to the brake band 17 by means of a spring force within a region of the brake drum 16. The member 30 is installed in such a manner that it is separated from the brake band 17 resisting the spring force through the operation of the manually operated member 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a driving force transmission system of a chain wheel that is rotatably supported in a casing and drives a saw blade chain. Brake drum and
A brake band wound around the brake drum, and a brake band which can be transferred from a loosened position where the brake drum can be rotated to a braking position where the brake drum is braked under the brake band without braking. Inertia which acts as a counteracting brake, also known as a kickback brake, which can be released via a hand guard U-section for a sudden stop of the chain, and which acts upon releasing the manually actuated element for starting the chainsaw Driving brake (Au
It relates to a power chain saw of the type equipped with a chain brake device having two release devices, the other of which is configured as a slaufbremse.

[0002]

BACKGROUND OF THE INVENTION Published German Patent Application No. 196
In a power chain saw equipped with a chain brake device known from U.S. Pat. No. 18,640, the repulsion brake (Kickback brake) for suddenly stopping the saw blade chain is provided by a strong repulsion brake spring. An adjusting lever to be loaded, the adjusting lever fixing one end of a brake band to be wound around the brake drum when transferring the collision brake from the ready position to an operating position for tightening the brake band to the brake drum; The brake band lever is rotated about a rotation axis fixed to the casing of the brake drum. On the other hand, the coasting brake (Auslaufbremse) is an actuating element for starting the power chainsaw (for example, a throttle lever in the case of a chain saw operated by an engine or an electric on / off in the case of a chain saw operated by an electric motor). (Off switch) and a brake band lever, and a relatively weak coasting spring that loads the brake band at the braking position.
The brake band lever has a second axis of rotation arranged parallel to its first axis of rotation and is pivotable about this second axis of rotation when the coasting brake is activated, When the collision brake is released, the operating member for starting the chainsaw is substantially free of reaction force. However, the technical cost of the lever mechanism to be realized in this case is relatively large. Moreover, since the lever mechanism is disposed in the front region of the chainsaw, a disadvantage in this case is that the power transmission distance from the operating member for starting the chainsaw to the lever mechanism is long.

[0003] Published German Patent Application No. 1961
In the case of a collision brake in an electric motor-type chainsaw equipped with a known chain brake device based on the specification of No. 4212, the brake band wound around the brake drum is also operated by the hand guard U-shaped member,
Due to the pulling of the front end of the brake band accompanying this, it is tightened around the brake drum. The coasting brake has a bending rod to which the other end of the brake band is fixed and which is preloaded by a ring spring. The bending rod is connected on the end side to an actuating member for starting the chainsaw, by means of which the actuating member closes an on / off switch arranged in the electric circuit of the electric motor. Can be When the actuating member is released, the bending rod pulls the end of the brake band based on the spring return force to tighten the brake band to the brake drum. In this case, the brake band is pulled in the direction opposite to the rotation direction of the brake drum, so that the automatic winding effect of the brake band as in the case of the collision braking does not occur. In the case of the prior art, the braking force must be designed accordingly, since the force component caused by the frictional force between the brake band and the brake drum acts against the braking force. Therefore, the technical costs for coasting braking are also high.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power chain saw which can achieve a large braking action despite a very small power consumption.

[0005]

Means for solving the above-mentioned problems of the present invention are as follows.
The coasting brake has a brake release member pressed against the brake band by spring force in the region of the brake drum, the brake release member being braked against the spring force by manual operation of the actuating member. It is at a point away from the belt.

[0006]

The advantages provided by the power chainsaw of the invention with the features as set forth in the characterizing part of claim 1 are that the construction of the lever mechanism for the chain brake device is simple and the production thereof is cheap. Therefore, the production cost of the chainsaw is significantly reduced. The power transmission lever in the coasting brake is preferably arranged near the actuating element for starting the chainsaw and is therefore advantageously arranged. Very little force is required for the braking action. This is because in the case of the coasting brake, the original braking action is released by the automatic wrapping effect of the brake band. The spring force applied to the brake element is used only to release the self-winding effect of the brake band and does not form the actual braking force.

[0007] Further advantageous configurations and refinements of the power chainsaw according to claim 1 are possible by means of the other features.

According to an advantageous embodiment of the invention, the brake release member has a two-armed power transmission lever pivotally held in the casing, the spring of which is loaded by a spring. One lever arm provided has a brake piece that rests on the brake band, and the other lever arm is coupled to the actuating member. In that case, the actuating member is formed integrally with the other lever arm, which is
In the case of a chainsaw driven by an electric motor, it is advantageous to load the switching element of an electrical on / off switch located in the electric circuit of the electric motor.

In order to optimally design the inertial driving brake, according to an advantageous embodiment of the invention, a brake release member (ie a brake piece on one lever arm) is provided.
It is important that the friction between the brake band and the brake band be smaller than the friction between the brake band and the brake drum. This can be achieved by appropriately designing the structure of the power transmission lever and / or the structure of the brake piece of the power transmission lever.

According to an advantageous embodiment of the invention, the brake piece is formed by a brake shoe fixed to or integrally formed with the lever arm, wherein the brake shoe is provided on the brake drum. It rests on the brake band with the braking surface cylindrically curved corresponding to the circumference. As a result, a surface contact of the spring-loaded lever arm with the brake band is obtained, and the magnitude of this surface contact makes it possible to adjust the friction effect. If necessary, the braking surface may be subjected to a film forming process or a quenching process, thereby affecting the friction coefficient.

According to an advantageous embodiment of the present invention, in order to prevent extreme wear of the brake band, which would cause the brake band to tear upon release of the collision brake (kickback brake), A stop is provided which cooperates with the brake release member, such that when the brake band reaches the minimum permissible thickness, the brake release member or the power transmission lever no longer presses against the brake band via the brake shoe. It is arranged so that it cannot generate power. In this case, the stopper is fixed to the casing side and cooperates with the power transmission lever or the brake shoe, or is formed on the brake drum and cooperates with the brake shoe that extends left and right beyond the brake band. It can also be done.

In a further embodiment of the invention, the power transmission lever is formed as a bent sheet metal part, and the brake piece is formed in an arc shape to fit the circumference of the brake drum.

In a further embodiment of the invention, it is also possible for the brake lever in the region of the brake piece to be fixed with a plurality of pressure rollers mounted on the brake band with relatively little friction.

According to a further embodiment of the present invention, a brake transmission piece is formed as a bead from a power transmission lever manufactured as a bent sheet metal part, and the brake transmission piece is linearly pressed to a brake band. Is also possible.

According to an advantageous embodiment of the invention, the brake shoe is received in a brake shoe guide fixed to the housing so as to be able to shift within a limited range in the circumferential direction of the brake drum and has a power transmission lever. The load can be applied with a spring force in the radial direction of the brake drum via the lever arm. The brake shoe and the brake shoe guide each have an inclined portion at each front end as viewed in the rotation direction of the brake drum. Both inclined parts, when shifting in the rotation direction of the brake drum, the inclined part of the brake shoe,
The brake shoe guides and the brake band are wedge-fitted to each other, so that strong radial pressure is exerted on the brake band and the brake drum, and the braking action is significantly enhanced. .

According to an advantageous embodiment of the invention, the collision brake has a two-arm brake lever pivotally mounted on the casing, with a hand guard on one lever arm of the two-arm brake lever. And the other lever arm of the two-armed brake lever is connected to a blocking member for blocking drive torque acting on the chain wheel. The rear end of the brake band is fixed to the casing, and the front end of the brake band wound around the brake drum in the rotation direction of the brake drum is fixed to the lever arm connected to the hand guard. Moreover, on the one hand, the brake band is released by the forward displacement of the hand guard and tightened on the circumferential surface of the brake drum with the turning of the two-arm brake lever caused by the release of the preloaded spring. And, on the other hand, can be shifted in the pulling direction regardless of the two-arm brake lever. By fixing the brake band to the two-arm brake lever in this way, the brake band moves forward with respect to the two-arm brake lever when the coasting brake is activated, and thus the brake band is tightly attached to the peripheral surface of the brake drum. Is guaranteed.

For this purpose, according to an advantageous embodiment of the invention, the front end of the brake band is fixed to a single-armed lever, which is connected to a hand guard by a two-armed brake. The lever is pivotally supported by a lever arm of the lever, and is supported by a stopper at a front edge of the lever arm on a side opposite to the brake band when a coasting brake is not applied.

According to an alternative embodiment of the invention, the front end of the brake band is fixed to the lever arm of a two-arm brake lever connected to a hand guard by a pin-slot joint, In addition, when the inertia operation brake is not applied, the pin of the joint comes into contact with the end of the elongated hole near the brake band. The slot can then be arranged in the lever arm of the two-arm brake lever or in the brake band itself. The pin is therefore fixed to the brake band or to the lever arm. In the latter case, the pin is advantageously formed by the edge of the brake lever, which penetrates the slot in the brake band, on the side opposite the brake drum.

According to an advantageous embodiment of the invention, the brake band section located between the brake drum and the two-arm brake lever in both cases of fixing the brake band to the two-arm brake lever, A spring force oriented away from the arm-type brake lever toward the brake drum acts. The spring force ensures that the brake band is returned to its initial position when the chain brake device is inactive. Said spring force is realized by a tension spring fixed at one end to the brake band and at the other end to the casing.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described in detail with reference to the drawings.

The electric motor-driven chainsaw, which is only shown in FIG. 1 with only the important chain brake device within the scope of the invention, has a casing 10 with a first handgrip 11 at the rear end of the casing. Are formed, and a plurality of support teeth 12 for setting a chainsaw on a work to be cut are formed on a front end surface of the casing. A second handgrip 13 is arranged near the front end face of the casing 10 and above the casing, the second handgrip being a U-shaped member in a transverse direction perpendicular to the longitudinal axis of the casing 10. (In other words, in FIG. 1, perpendicular to the drawing plane). A hand guard 14 is arranged in front of the second hand grip 13 and is connected to a chain brake device and turns to two turning positions A and B, as will be described in detail later. be able to.

The chain brake device is a brake drum 1
6 and a brake band 17 wound around the brake drum 16. The brake band brakes the brake drum 16 from a loosened position where the brake drum 16 can rotate under the brake band 17 without braking. To the braking position. The brake drum 16 is fixed to the output shaft 44 of the drive motor in a non-twistable manner, and a drive pinion 45 is also fixed to the output shaft in a non-twistable manner.
The drive pinion drives a chain wheel 46 rotatably supported in the casing 10 via a transmission (see FIGS. 13 and 14). The chain wheel 46 is engaged with a saw blade chain 47 guided along a sword (Schwert) projecting from the casing 10 as is well known.

The chain brake device is released (actuated) by two actuators, one of which is configured as a repulsion brake (kickback type brake) 18 for sudden stopping of the saw blade chain. And, on the other hand, a coasting brake which acts immediately when a drive motor, which is configured as an electric motor in the present invention, is interrupted by an electric on / off switch 20 arranged in the electric circuit of the electric motor. 19.

The collision brake 18 has a two-armed brake lever 21 pivotally supported at the center of gravity 29 of the casing 10, and has one lever arm 211 of the brake lever.
Is engaged with the hand guard 14, and the other lever arm 21
2 is connected via a toggle lever 36 to a blocking member 22 for blocking the driving torque acting on the chain wheel 46. When the chain wheel 46 is driven by an electric motor as in this example, the blocking member 22 acts on a breaker arranged in a current circuit of the electric motor to stop the electric motor. The toggle lever 36 has a slider 361 acting on the blocking member 22 and capable of shifting in the axial direction by receiving a preload force of the compression spring 37, one end pivotally connected to the slider 361 and the other end being a lever arm. And a connecting member 362 pivotally attached to the reference numeral 212. When the hand guard 14 is in the position A, the toggle lever 36 is extended (as shown by the solid line in FIG. 1) and the compression spring 37 is contracted. The brake band 17 is fixed at its rear end 171 to the casing 10, is guided via deflecting guide pins 23 fixed at the casing 10, and moves in the direction of rotation of the brake drum 16.
After being wrapped around 6, it is fixed at its front end 172 to a lever arm 211 connected to the hand guard 14. In this case, the position of the front end 172 of the brake band 17 is fixed by hand guard 14 in the direction of arrow 15 in FIG.
The forward displacement of the brake lever 21 causes the brake lever 21 to turn, thereby tightening the brake band 17 against the brake drum 16, while allowing the brake band to be shifted in the pulling direction regardless of the brake lever 21.

In the embodiment shown in FIG. 1, the position of the front end 172 of the brake band 17 is fixed by fixing the front end 172 of the brake band 17 to the single-armed lever 24 and holding the single-armed lever with the hand. Brake lever 2 connected to guard 14
This is realized by positioning the first lever arm 211 so as to be pivotable about the pivot axis 25. When the coasting brake 19 is in the inactive state, that is, when the coasting brake is in the ready position during operation of the chainsaw, the single-arm lever 24 is moved to the lever arm 211 by the stopper 26 and to the brake band 17. Abuts on the front edge 211a (see FIG. 4) on the side opposite to that of FIG. Inertial operation brake 1
9 is actuated, the front end 172 of the brake band 17 is shifted forward, and accordingly the single-arm lever 2 is moved.
4 is turned clockwise as viewed in FIG.

In this regard, see also the double-arm brake lever 21 shown in an enlarged view in FIGS. In this case, FIG. 2 shows the position of the two-armed brake lever 21 during operation of the chainsaw in a state where the chain brake device is not operated. FIG. 3 shows the position of the two-arm brake lever 21 when the coasting brake 19 is released, and FIG.
The position of the two-armed brake lever 21 when is released is shown. The tension spring 27 serves to ensure that the brake band 17 is returned to the initial position of the brake band when the chain brake device is inactive, and that one end of the tension spring 27 is connected to the brake lever 21 and the brake lever. The tensioning force in the direction of the brake band 17 is oriented in the direction of the brake drum 16 since it engages with the brake band section located between it and the drum 16 and the other spring end is fixed on the casing side. It is attached. Under the action of the tension spring 27, the stopper 26 of the single-arm lever 24 is in contact with the front edge 211a of the lever arm 211 at the preparation position (FIG. 2) of the chain brake device.

The repulsion brake 18 causes the hand guard 14 to abut on the hand of the user gripping the second hand grip 13 based on the upward repulsion of the casing 10, and is thereby shown by a solid line in FIG. Is released by turning in the direction of arrow 15 from the position A to the position B shown by the broken line. Therefore, the two-arm brake lever 21 is shown in FIG.
Then, it is turned clockwise (as can be seen from FIG. 4) to the dashed line position. By this pivoting movement, the toggle lever 36 in the overpressure state is unlocked, and the preloaded compression spring 37 presses the two-armed brake lever 21 forward. The electric motor is cut off via the blocking member 22. Since the brake lever 21 loaded by the compression spring 37 pulls the brake band 17 forward and tightens the brake band on the peripheral surface of the brake drum 16, the effect of automatically winding the compression spring 37 and the brake band 17 is improved. As a result, a braking action takes place here, and the brake drum 16 is braked impulsively.

The coasting brake 19 has a brake release member 30 which is pressed against the brake band 17 by spring force in the region of the brake drum 16 and which is used to actuate the chain saw.
By the manual operation of 8, the brake band 17 is separated against the spring force. In the embodiment shown in FIG. 1, the brake release member 30 is configured as a two-armed power transmission lever 31 rotatably held in the casing 10, and is provided by a compression spring 32 supported by the casing 10. The one lever arm 311 of the power transmission lever 31 to be loaded is connected to the brake piece 31 mounted on the brake band 17.
1a, and the other lever arm 312 is connected to the operating member 28, and is integrally connected to the operating member 28 in this embodiment. Under the action of the compression spring 32, the power transmission lever 31 occupies the position shown by the broken line in FIG. 1, in which the brake piece 311 a presses the brake band 17 against the peripheral surface of the brake drum 16 in the radial direction. And the electric motor is disconnected. When the power transmission lever 31 is moved to the position shown by the solid line in FIG. 1 by pushing the operating member 28 into the first hand grip 11, the brake piece 311a separates from the brake band 17 and thus the brake drum 16 Is the brake belt 17
, And the lever arm 312 loads the switching element 201 of the on / off switch 20, which itself closes the switching contact of the on / off switch 20. In conjunction with this, the chainsaw was started,
And the saw blade chain is driven by the sheave until the actuating member 28, manually held in this position, is released again.
In the case of this release, the power transmission lever 31 is
Based on the spring force, the lever turns back to the position shown by the broken line in FIG. 1 and the lever arm 312 releases the switch element 201 of the on / off switch 20, so that the on / off switch opens the switching contact, And shut off the electric motor. At the same time, the brake piece 311a is pressed against the brake band 17 by the compression spring 32. As a result, the brake band 17 shifts in the radial direction with respect to the brake drum 16. Brake drum 1 with brake band 17 rotating
Immediately upon contact with 6, the friction produces a tangential force component on the brake drum 16, which tangential force component further wraps the brake band 17 around the brake drum 16 and enhances the wrapping action ( Thus, the brake drum 16 is braked. In this case, the front end 172 of the brake band 17 shifts forward against the spring force of the tension spring 27, so that the two-arm brake lever 2
The single arm lever 24, which is pivotably held at 1, thus occupies the position shown in FIG.

Important points for obtaining the above-mentioned braking effect when the coasting operation brake 19 is released are that the brake piece 311a of the two-armed power transmission lever 31 and the brake band 17
Is smaller than the friction effect between the brake band 17 and the brake drum 16. This can be obtained by appropriately designing the structure of the two-armed power transmission lever 31 and / or the brake piece 311a.

In the embodiment shown in FIG.
1a is a brake shoe 33 fixed to the lever arm 311.
It is configured as The brake shoe 33 has a cylindrically curved braking surface and abuts against the brake band 17 adapted to the drum peripheral wall of the brake drum 16, so that the surface contact of the brake shoe 33 along the brake band 17 is obtained. The shape of the braking surface or contact surface determines the frictional action between the brake shoe 33 and the brake band 17,
The friction effect can additionally be influenced by coating or quenching of the braking surface.

As can be seen from the enlarged cross-sectional view of FIG. 10, the brake shoe 33 is received in a U-shaped brake shoe guide 38 formed by the lever arm 311 and is radial with respect to the brake drum 16. , Is supported by the bottom of the brake shoe guide 38 via the web 39. In order to prevent the brake band 17 from being worn excessively so as to be broken when the collision brake 18 (kickback brake) is applied, the feeding movement of the brake shoe 33 is controlled by a stopper 40 (see FIGS. 11 and 12). The stop is limited and is such that the power transmission lever 31 can no longer exert a crimping force on the brake band 17 via the brake shoe 33 when the brake band has the minimum permissible wall thickness. Therefore, since the coasting brake 19 does not function, the user can control the brake band 17.
You have to be aware that you have to replace the.

For this reason, as shown in FIG. 11, the brake shoes 33 projecting left and right beyond the brake band 17 come into contact with the stopper 40 when the minimum allowable thickness of the brake band 17 is reached. So that it is arranged in the casing 10. Alternatively, the two-arm power transmission lever 31
It is also possible to cooperate the brake shoe guide 38 formed by the lever arm 311 with a stopper fixed to the casing, in which case the stopper must of course be arranged in the casing 10 accordingly. become.

In the variation shown in FIG.
Are formed on the brake drum 16. In this case, the brake drum 16 is configured to be wider than the brake band 17 placed thereon, and receives the brake band in a circumferential groove 41 formed in the center of the brake drum 16.
The radial depth of the circumferential groove 41 is such that when the brake band 17 reaches the minimum allowable thickness, the brake shoe 33 projecting beyond the brake band 17 is moved to the peripheral surface of the brake drum 16 forming the stopper 40. On the brake belt 1
It has been established that 7 is no longer crimped on the brake drum 16 and the impact brake 18 is no longer functioning.

In an alternative embodiment, the two-armed power transmission lever 31 has a brake piece 311 formed as an arc segment.
It is also possible to constitute a sheet metal bent molded part in which a is directly molded. There is no need to form the brake shoe as a separate part. Also, instead of brake shoes,
It is also possible to provide one or more pressure rollers on the lever arm 311, which further reduces the frictional force.
Furthermore, from the lever formed as a sheet metal bent molded part, the brake piece 311a is stamped and formed as a bead,
It is also possible to press the brake piece linearly onto the brake band 17.

In the embodiment of the chainsaw shown as a partially enlarged view in FIGS.
Means that the brake shoe 33 'is a two-armed power transmission lever 31
The brake drum 16 is received in the brake shoe guide 38 'fixed to the casing so as to be able to shift within a limited range in the circumferential direction of the brake drum 16 instead of being fixed to the casing. The brake shoe 33 ′ and the brake shoe guide 38 ′ have inclined portions 42 and 43 at each front end as viewed in the rotation direction of the brake drum 16. Both inclined parts 4
2 and 43 are arranged so that the inclined portion 42 of the brake shoe 33 ′ is wedged between the inclined portion 43 of the brake shoe guide 38 ′ and the brake band 17 when shifting in the rotation direction of the brake drum 16. Has been adapted to. FIG. 13 shows the coasting operation brake 19 in a relaxed state, that is, the operation state of the chainsaw, and FIG. 14 shows the coasting operation brake 19 in the operation state, that is, the suspension state of the chainsaw. In FIGS. 13 and 14, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

During operation of the chainsaw, the operating member 28 is pushed into the first handgrip 11 and the lever arm 311 of the two-armed power transmission member 31 is
2 is separated from the brake shoe 33 'against the force of the spring. The brake shoe rests loosely on the brake band 17, and the brake drum 16 can rotate under the brake band 17 without trouble (FIG. 1).
3). When the operating member 28 is released, the two-armed power transmission member 31 rotates counterclockwise by receiving the spring force of the compression spring 32. The drive of the electric motor of the chainsaw is cut off, and the lever arm 311 of the two-armed power transmission lever 31 is pressed toward the brake shoe 33 '. The brake shoe 33 'crimped to the brake band 17 is shifted in the rotation direction of the brake drum 16 by the movement of the brake band 17, and the inclined portion 42 of the brake shoe 33'
The brake shoe guide 38 is wedge-fixed below the inclined portion 43. Accordingly, the pressure acting on the brake band 17 and the brake drum 16 is increased, and as a result, the automatic wrapping action of the brake band 17 is strengthened, and thus the braking action is enhanced.

FIGS. 5 to 7 show two-arm type brake lever 2.
1, an alternative mounting of the front end 172 of the brake strip 17, i.e. the brake, like the single-arm lever 24 pivotally mounted on the two-arm brake lever 21 in the event of release of the coasting brake 19. An alternative mounting scheme allowing the pulling movement of the band 17 is shown. In this case, the front end 172 of the brake band 17 is pin 3
4, and the pin is shiftably received in an elongated hole 35 formed in a lever arm 211 connected to the hand guard 14. In this case, the elongated hole 35 extends over the entire width of the lever arm 211 on an extension of the brake band 17. The preparation positions of the chain brake device shown in FIG.
Do not work together and the chainsaw is in operation, the pin 34 is brought into contact with the end of the elongated hole 35 near the brake band 17 by the tensile force of the tension spring 27, so that the brake band 17 Are always returned securely, and the brake drum 16 can rotate freely under the brake band 17.

FIGS. 8 and 9 show different modes of mounting the front end portion 172 of the brake band 17 in the two-armed brake lever 21. FIG. In this case, a long hole 48 is provided in the front end region of the brake band 17, and the lever arm 211 projects through the long hole. In the preparation position of the chain brake device shown in FIG. 8, the front edge 491 of the piercing portion 49 formed in the two-arm type brake lever 21 on the side opposite to the brake drum 16 has the spring force of the tension spring 27. Under the action, it is in contact with the front end of the elongated hole 48. When the coasting brake 19 operates, the brake zone 17
Shifts forward without changing the posture of the two-armed brake lever 21 based on the size of the elongated hole 48 (FIG. 9).

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a chainsaw portion equipped with a chain brake device equipped with a collision brake and a coasting brake.

FIG. 2 is an enlarged side view of a brake lever of the chain brake device of FIG. 1 in an inactive state.

FIG. 3 is an enlarged side view of a brake lever of the chain brake device of FIG. 1 in a state in which an inertial operation brake is in operation;

FIG. 4 is an enlarged side view of a brake lever of the chain brake device of FIG. 1 in a state in which a collision brake is applied;

FIG. 5 is a side view corresponding to FIG. 2 of a brake lever according to a second embodiment.

FIG. 6 is a side view corresponding to FIG. 3 of a brake lever according to a second embodiment.

FIG. 7 is a side view corresponding to FIG. 4 of a brake lever according to a second embodiment.

FIG. 8 is a side view corresponding to FIG. 2 of a brake lever according to a third embodiment.

FIG. 9 is a side view corresponding to FIG. 3 of a brake lever according to a third embodiment.

FIG. 10 is a partial enlarged cross-sectional view taken along the line XX of FIG. 1;

FIG. 11 is an enlarged sectional view corresponding to FIG. 10 of a variation of a brake shoe or a brake drum.

FIG. 12 is an enlarged sectional view corresponding to FIG. 10 of a variation of a brake shoe or a brake drum.

FIG. 13 is a longitudinal cross-sectional view of the chain saw portion during operation, showing a state in which the coasting operation brake according to the variation mode is released.

14 is a longitudinal sectional view corresponding to FIG. 13 of a chain saw portion when the coasting operation brake is shown in an activated state and is cut off.

[Explanation of symbols]

Reference Signs List 10 casing, 11 first hand grip, 12 support teeth, 13 second hand grip, 14 hand guard, 15 arrow, 16
Brake drum, 17 Brake band, 18
Opposition brake (kickback brake), 19
Coasting brake, 20 on / off switch,
21 two-armed brake lever, 22 blocking member,
23 deflection guide pin, 24 single arm lever, 25
Pivot axis, 26 stopper, 27 tension spring, 28 operating member, 29 center of gravity, 30
Brake release member, 31 two-armed power transmission lever, 32 compression spring, 33, 33 'brake shoe, 34 pin, 35 slot, 36
Toggle lever, 37 compression spring, 38,3
8 'U-shaped brake shoe guide, 39 web, 40 stopper, 41 circumferential groove, 42, 43
Inclined part, 44 output shaft, 45 drive pinion, 46 chain wheel, 47 saw blade chain, 48
Long hole, 49 bay entry, 171 rear end of brake band, 172 front end of brake band, 201 switch element, 211 lever arm, 211a front edge of lever arm, 212 lever arm, 311 lever arm of one of power transmission levers , 311a brake piece, 31
2 The other lever arm of the power transmission lever, 361 slider, 362 coupling member, 491 leading edge

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Jürgen Dorata Germany Sepnitz Ring Strasse 1 (72) Inventor Christian Hermes Germany Sepnitz Albert Kunze-Weg 32

Claims (10)

[Claims] A chain wheel (4) rotatably supported in a casing (10) and driving a saw blade chain (47).
6) A brake drum (16) arranged in the driving force transmission system, and a brake band (17) wound around the brake drum (16), and under the brake band (17) without braking. A brake band (17) that can be shifted from a rotatable loose position of the brake drum (16) to a braking position for braking the brake drum (16), and a hand guard U-shaped member ( 1
Coasting brake (19), which constitutes one as a collision brake (18), also referred to as a kickback brake releasable via 4) and acts when releasing the manually actuated member (28) for starting the chainsaw. ) In a power chain saw of the type equipped with a chain brake device having two release devices constituting the other,
The coasting brake (19) is connected to the brake drum (16).
A brake release member (30) which is pressed against the brake band (17) by spring force in the region of, which brake release member opposes said spring force by manual operation of the actuating member (28). A power chain saw equipped with a chain brake device, wherein the power chain saw is separated from a brake band (17). 2. A frictional action between a brake release member (30) and a brake band (17) is caused by the brake band (1).
2. The power chainsaw according to claim 1, wherein the coasting brake (19) is configured to have less frictional action between the brake drum (7) and the brake drum (16). 3. A brake release member (30) having a two-armed power transmission lever (31) pivotably held in a casing (10), wherein the two-armed power transmission lever includes:
One lever arm (31) loaded by the spring (32)
1) the brake piece (31) resting on the brake band (17)
Power chain saw according to claim 1 or 2, comprising 1a) and the other lever arm (312) is connected to the actuating member (28). 4. A brake piece (311a) comprising a brake shoe (33) fixed to or integrally formed with a lever arm (311), wherein the brake shoe is formed by a film forming process or a film forming process. 4. The brake according to claim 3, wherein the brake surface rests on the brake band with the quenched braking surface, and the braking surface is cylindrically curved to fit the peripheral wall of the brake drum. Power chainsaw. 5. A repulsion brake (18) having a two-arm brake lever (21) pivotably mounted on a casing (30), one lever arm (211) of the two-arm brake lever. Is engaged with a hand guard (14) and the other lever arm (212) of the two-armed brake lever is
The rear end (171) of the brake band (17) is fixed to the casing (10), and is connected to a blocking member (22) for blocking the driving torque acting on the chain wheel. ), The front end (172) of the brake band (17) wound around the brake drum (16) is fixed to the lever arm (211) connected to the hand guard (14). And the brake band (17) is released on the one hand by the forward displacement of the hand guard (14) and the release of the preloaded spring (37) causes the release of the two-arm brake lever (21). With the turning, it is tightened on the peripheral surface of the brake drum (16) and, on the other hand, can be shifted in the pulling direction irrespective of the two-armed brake lever (21). It has become earthenware pots, power chain saws according to any one of claims 1 to 4. 6. A front end (172) of a brake band (17).
Is fixed to a single-armed lever (24), and the single-armed lever pivotally pivots on a lever arm (211) of a two-armed brake lever (21) coupled to a hand guard (14). It is supported and supported by the stopper (26) at the front edge (211a) of the lever arm (211) on the side opposite to the brake band (17) when the inertia operation brake (19) is not applied. The power chainsaw according to claim 5, wherein 7. A front end (172) of a brake band (17).
Are fixed to the lever arm (211) of the two-arm brake lever (21) connected to the hand guard (14) by pin-elongated joints (34, 35), and the inertial operation brake (19) 6. The power chainsaw according to claim 5, wherein the pin (34) of the joint comes into contact with the end of the elongated hole (35) near the brake band (17) when no operation is performed. 8. A brake band section located between a brake drum (16) and a two-armed brake lever (21),
A spring force acting in a direction away from the two-armed brake lever (21) acts on the tension spring having one end fixed to the brake band (17) and the other end fixed to the casing (10). Power chainsaw according to claim 6 or 7, generated by (27). 9. When the chain wheel (46) is driven by an electric motor, the lever arm (312) of the two-armed power transmission lever (31) supporting the operating member (28) is connected to the electric motor in a current circuit. Power chainsaw according to one of the claims 3 to 8, which loads a switch element (201) of an electrical on / off switch (20) located at the end of the power chain saw. 10. An interrupting member (22) for interrupting a driving torque acting on a chain wheel (46) is an adjusting force transmitting member for loading an electric circuit breaker located in a current circuit of an electric motor. A power chainsaw according to claim 9.