JP5194554B2 - Power tool - Google Patents

Description

  The present invention relates to a power tool in which a lubricant is contained in a sealed chamber formed in a housing.

  An electric hammer as one form of a power tool accommodates an electric motor as a drive source in a housing, and drives a tip tool in a straight line by pressure fluctuation in a mechanism chamber defined in the housing to perform predetermined processing. A striking mechanism that performs the work and a reciprocating motion conversion mechanism that converts the rotation of the electric motor into a reciprocating motion of the piston by reducing the rotation of the electric motor by a reduction gear are housed.

By the way, in such an electric hammer, the mechanism chamber in which the striking mechanism and the reciprocating motion conversion mechanism are housed is filled with a lubricant in order to improve durability of each member, reduce friction loss, etc. As the agent, one having a low viscosity and high fluidity is used so as not to impair the lubricity even at low temperatures. For this reason, the mechanism chamber is sealed with a plurality of types of sealing members such as an O-ring, an oil seal, and a ball bearing with a seal (see, for example, Patent Document 1).
JP-A-1-316178

  The electric hammer is provided with a striking mechanism in the mechanism chamber of the housing that follows the reciprocating motion of the piston and reciprocates the striking element and the intermediate element at high speed to transmit the striking force to the tip tool. It is necessary to fill a relatively large amount of highly functional lubricant.

  However, when a relatively large amount of highly fluid lubricant is filled in the mechanism chamber as described above, if the pressure in the mechanism chamber rises due to heat generated by reciprocating motion of the piston or the like, the fluid is heated and heat flow is increased. This causes a problem that the lubricant easily flows out of the mechanism chamber from the seal portion.

  The present invention has been made in view of the above problems, and an object thereof is to provide a power tool capable of suppressing leakage of a lubricant.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a drive source and a speed reduction mechanism that decelerates the rotation of the drive source are accommodated in a housing, and a lubricant is accommodated in a sealed chamber formed in the housing. In the power tool formed in the power tool, the rotating member that constitutes a part of the speed reduction mechanism is formed with a communication path that allows the sealed chamber and the atmosphere to communicate with each other, and protrudes from the periphery to the sealed chamber side open end of the communication path. A rib is formed.

Another feature of the present invention is that the open end of the communication chamber on the side of the sealed chamber is opened in a space formed inside the rotating member.

Still another feature of the present invention is that a communication path forming member, which is a separate member, is fitted into the space of the rotating member, and the communication path is formed in the communication path forming member .

Still another feature of the present invention is that the communication path forming member is formed of an elastic body .

According to a second aspect of the present invention, in the first aspect of the present invention, a filter is provided in the communication path.

According to a third aspect of the present invention, in the second aspect of the present invention, the filter is provided on both sides of the communication path.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the rotating member is a crankshaft constituting a part of a reciprocating motion conversion mechanism.

According to the first aspect of the present invention, even if the air in the sealed chamber is heated and expanded by the heat generated by the drive of the speed reduction mechanism in the housing, the expanded air passes through the communication path formed in the rotating member. Since it passes through and is discharged into the atmosphere, the pressure increase in the sealed chamber is suppressed, and the outflow of the lubricant heated by heat generation and having improved fluidity to the outside of the sealed chamber is suppressed. In addition, the sprayed or droplet-like lubricant contained in the air in the sealed chamber is prevented from flowing into the communication path by the centrifugal action of the rib that rotates together with the rotating member. Outflow is suppressed.

Further , according to the present invention , the communication path forming member which is a separate member in which the communication path and the rib are formed is incorporated in the space of the rotating member, so that the existing rotating member is not greatly changed and the communication path is formed therein. Can be provided.

Furthermore, according to the present invention , since the communication path forming member is made of an elastic body, the communication path forming member can be elastically deformed and easily incorporated into the space in the rotating member.

According to the second aspect of the present invention, the sprayed or droplet-like lubricant contained in the air in the sealed chamber is filtered by the filter and separated from the air in the process of flowing through the communication path. Leakage to the outside of the sealed room is prevented.

According to the third aspect of the present invention, since the filters are provided on both sides of the communication path, the spray or droplet-like lubricant contained in the air in the sealed chamber is filtered in two stages on both sides of the communication path, Leakage of the lubricant to the outside of the sealed chamber is further effectively suppressed.

According to the fourth aspect of the present invention, the leakage of the lubricant to the outside of the sealed chamber can be suppressed by the communication path and the rib provided in the crankshaft constituting a part of the reciprocating motion conversion mechanism. In particular, in a configuration in which the connecting rod always moves so as to cross the communication path that opens on the upper surface of the crankshaft, the flow of the lubricant with increased fluidity into the communication path is suppressed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 is a perspective view of an electric hammer as an embodiment of a power tool according to the present invention, FIG. 2 is a cutaway side view of the electric hammer, and FIG. 3 is an enlarged sectional view of the main part of the electric hammer.

  An electric hammer 1 according to the present embodiment performs a required work by applying a striking force to a tip tool 3 mounted on a tool holding unit 2, and a motor is provided from a cylinder crankcase 4 incorporating a striking mechanism. The housing 5 extends substantially vertically downward. A side handle 6 is provided on the front end side of the cylinder crankcase 4, and a handle 7 is provided behind the cylinder crankcase 4 and the motor housing 5 (on the right side in FIGS. 1 and 2). Works by holding the side handle 6 and the handle 7. The handle 7 is provided with a switch 8.

  As shown in FIG. 2, an electric motor 9 as a drive source is accommodated in the motor housing 5 in a vertically placed state, and is upward from a ball bearing 11 of an output shaft (motor shaft) 10 of the electric motor 9. A pinion 12 is formed at the protruding end. A cooling fan 13 is bound to a portion of the output shaft 10 below the ball bearing 11.

  On the other hand, in the rear end portion of the cylinder crankcase 4, a crankshaft 14 is vertically supported by a ball bearing 15 with a seal and a needle bearing 16 so as to be vertically rotatable. A gear 17 is attached to the. The gear 17 meshes with the pinion 12 formed at the upper end of the output shaft 10 of the electric motor 9, and the pinion 12 and the gear 17 constitute a speed reduction mechanism. A crankpin 18 is integrally projected from the upper end of the crankshaft 14 at a position eccentric from the center of rotation of the crankshaft 14.

  A cylinder 19 is horizontally disposed in the cylinder crankcase 4, and a piston 20 and a striker 21 are fitted into the cylinder 19 so as to be reciprocally linearly movable in the front-rear direction. In the cylinder 19, an air chamber S1 that is substantially sealed by the piston 20 and the striker 21 is defined. An intermediate element 22 is disposed in front of the striker 21 so as to be movable back and forth. The front end surface of the intermediate element 22 abuts on the rear end face of the tip tool 3, and the rear end face is in contact with the front end face of the striker 21. It touches. The piston 20, the striker 21, the intermediate piece 22, and the like constitute an impact mechanism.

  Further, the piston 20 is connected to the crankshaft 14 via a connecting rod 23. That is, one end of the connecting rod 23 is connected to the pinton 20 by the piston pin 24, and the other end is connected to the crankpin 18 of the crankshaft 14. As will be described later, the rotation of the crankshaft 14 is connected to the cylinder of the piston 20 by the connecting rod 23. 19 is converted into a reciprocating linear motion within 19. Therefore, the crankshaft 14, the connecting rod 23, etc. constitute a reciprocating motion conversion mechanism.

  Thus, each component constituting the striking mechanism and the reciprocating motion conversion mechanism is housed in a mechanism chamber S2 which is a sealed chamber defined in the cylinder crankcase 4, and the fluidity is contained in the mechanism chamber S2. A high lubricant is filled, and each part is lubricated by the lubricant to improve durability and reduce friction loss. The mechanism chamber S2 is sealed by O-rings 25 and 26, an oil seal 27, and the ball bearing 15 with a seal, and leakage of the lubricant filled inside is prevented.

  By the way, as shown in detail in FIG. 3, a space composed of through holes 14a and 14b having large and small diameters is formed at the center of the crankshaft 14, and the through hole 14a on the large diameter side is formed in the mechanism chamber S2. The small-diameter through hole 14b is open in the motor housing 5 communicating with the atmosphere. The large diameter side through hole 14a is fitted with a communication path forming member 28 integrally formed of an elastic body such as rubber. The upper surface side and the lower surface side of the communication path forming member 28 in the through hole 14a. The felt is provided with a first filter 29 and a second filter 30, respectively. Since the communication path forming member 28 is made of an elastic body such as rubber, it can be elastically deformed and can be easily incorporated into the through hole 14a of the crankshaft 14. After the communication path forming member 28 is assembled in the through hole 14a of the crankshaft 14, the communication path forming member 28 is in close contact with the inner periphery of the through hole 14a. No gap is formed between them, and leakage of the lubricant from the gap is prevented.

  A communication passage inlet 28a and a communication passage outlet 28b are formed at the central portions of the upper and lower surfaces of the communication passage forming member 28, respectively. 31 is erected integrally. A large volume first communication passage chamber S3 is formed inside the communication passage forming member 28, and a small volume second communication passage chamber S4 is formed at the bottom of the communication passage forming member 28. The first communication passage chamber S3 and the second communication passage chamber S4 are communicated with each other by a passage 31a in the rib 31.

Thus, the through hole 14a of the crankshaft 14, the communication passage inlet 28a of the communication passage forming member 28, the first communication passage chamber S3, the passage 31a of the rib 31, the second communication passage chamber S4, and the communication passage forming member 28 are connected. The passage outlet 28b and the through hole 14b of the crankshaft 14 constitute a communication passage that allows the mechanism chamber S2 to communicate with the atmosphere, and the inside of the first communication passage chamber S3 of this communication passage, that is, the mechanism chamber S1 of the communication passage. The rib 31 is open at a side open end in a state of protruding upward from the surroundings.
The first filter 29 and the second filter 30 are provided on both upper and lower sides of the communication path.

  Next, the operation of the electric hammer 1 configured as described above will be described.

  When the switch 8 is turned on and the electric motor 9 is activated, the rotation of the output shaft 10 is decelerated by the pinion 12 and the gear 17 and transmitted to the crankshaft 14, and the crankshaft 14 is driven to rotate at a predetermined rotational speed. Is done. Then, the rotation of the crankshaft 14 is converted into a reciprocating linear motion of the piston 20 by the connecting rod 23, and the piston 20 moves in a reciprocating linear motion in the cylinder 19 to generate a pressure fluctuation in the air chamber S1. The force is transmitted to the tip tool 3 through the striking element 21 and the intermediate element 22.

  By the way, compression heat is generated by compressing air in the air chamber S1, and heat is generated by sliding friction of each component. Therefore, the cylinder crankcase 4 is heated, and a mechanism chamber formed therein. The lubricant in S2 is also heated to increase its fluidity. In such a state, since the mechanism chamber S2 is also heated, the air in the chamber expands to increase the internal pressure of the mechanism chamber S2, and the lubricant whose fluidity has been increased by heating easily leaks out of the mechanism chamber S2. Become.

  However, in the present embodiment, a space composed of through holes 14a and 14b having different diameters is formed in the crankshaft 14, and the first filter 29, the second filter 30, and the communication path forming member 28 are incorporated in the space. The expanded air in the mechanism chamber S2 passes through the first filter 29 from the through hole 14a of the crankshaft 14, passes through the communication path forming member 28, passes through the second filter 30, and passes through the through hole 14b to the motor. It is discharged into the atmosphere through the housing 5. Since the air in the mechanism chamber S2 is discharged to the atmosphere in this way, even if the mechanism chamber S2 is heated, the internal pressure does not increase, and the lubricant filled inside leaks out of the mechanism chamber S2. Is suppressed.

  Further, a relatively large particle component is removed by the first filter 29 from the spray-like or droplet-like lubricant contained in the air in the mechanism chamber S2. The lubricant that has passed through the first filter 29 flows into the first communication passage chamber S3 from the communication passage inlet 28a of the communication passage forming member 28 together with air. Here, since the communication path forming member 28 rotates together with the crankshaft 14, the lubricant contained in the air flowing into the first communication path chamber S3 moves outward in the radial direction by the centrifugal force and is moved to the second direction. It collides with the inner peripheral wall of the one communication passage chamber S3, drops along the inner peripheral wall, accumulates at the bottom of the first communication passage chamber S3, and is separated from the air. Therefore, leakage of the lubricant to the outside of the mechanism chamber S2 is suppressed, and only air is discharged into the atmosphere.

  Further, a rib 31 protruding upward from the surroundings is opened in the first communication passage chamber S3, and the rib 31 rotates together with the crankshaft 14. Therefore, the air and lubricant in the first communication passage chamber S3. The flow into the passage 31 a in the rib 31 is suppressed by the centrifugal action of the rib 31. Even if air and a lubricant flow into the passage 31a in the rib 31 from the first communication passage chamber S3, the lubricant contained in the air reliably passes through the second filter 30 through the second communication passage chamber S4. The clean air from which the lubricant has been removed is discharged from the small diameter side through hole 14b through the motor housing 5 into the atmosphere.

  When the electric hammer 1 is driven, the connecting rod 23 always moves so as to cross the through hole 14a opened on the upper surface of the crankshaft 14, so that a large amount of lubricant with increased fluidity is present in the through hole 14a. Will not flow into.

  After the driving of the electric hammer 1 is stopped, the mechanism chamber S2 is naturally cooled, so that the air inside is also cooled and the volume thereof is reduced. As a result, the mechanism chamber S2 has a negative pressure, and the outside air flows from the through hole 14b of the crankshaft 14 through the second filter 30, the communication path forming member 28, and the first filter 29 into the mechanism chamber S2. At this time, the lubricant adhering to the first filter 29 and the second filter 30 is reduced into the mechanism chamber S2 together with the inflowing air. For this reason, the 1st filter 29 and the 2nd filter 30 are hard to raise | generate clogging, and can maintain high filtration performance over a long period of time. In the present embodiment, since the felt is used for the first filter 29 and the second filter 30, the thickness and the packing density can be easily adjusted. can do.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is an enlarged cross-sectional view of the main part of the electric hammer according to the second embodiment of the present invention. In this figure, the same elements as those shown in FIG. Will not be described again.

  In the present embodiment, a communication passage 32 that allows the mechanism chamber S2 and the atmosphere to communicate with each other is formed in the axial center portion of the crankshaft 14, and a circular hole-shaped recess 14c is formed on the upper surface of the crankshaft 14. A ring-shaped rib 14d protruding from the periphery is integrally formed at the open end of the communication path 32 on the mechanism chamber S2 side (upper side). Since the rib 14d is formed in the recess 14c and does not protrude upward from the upper surface of the crankshaft 14, the rib 14d does not interfere with the connecting rod 23 and impair the operation thereof.

  Thus, even in the present embodiment, even if the air in the mechanism chamber S2 is heated and expanded by the heat generated by the drive of the speed reduction mechanism composed of the pinion 12 and the gear 17, the expanded air remains in the crankshaft 14. Is discharged into the atmosphere through the communication passage 32 formed in the inner wall, so that an increase in pressure in the mechanism chamber S2 is suppressed, and the lubricant that has been heated by heat generation and has improved fluidity flows out of the mechanism chamber S2. It is suppressed.

  Further, the spray-like or droplet-like lubricant contained in the air in the mechanism chamber S2 is prevented from flowing into the communication path 32 by the centrifugal action of the rib 14d that rotates together with the crankshaft 14, and therefore the mechanism chamber. The outflow of the lubricant to the outside of S2 is suppressed.

  In the above, the embodiment in which the present invention is applied particularly to an electric hammer has been described. However, the present invention is similarly applied to other arbitrary power tools including a power tool such as a hammer drill and a grinder and an air tool. Thus, the same effect as described above can be obtained.

  In the above embodiment, the example in which the communication path is formed in the crankshaft 14 has been described. However, the communication path can be formed in any other rotating member that faces the sealed chamber formed in the housing. .

1 is a perspective view of an electric hammer according to Embodiment 1 of the present invention. It is a fracture | rupture side view of the electric hammer which concerns on Embodiment 1 of this invention. It is an expanded sectional view of an electric hammer principal part concerning Embodiment 1 of the present invention. It is an expanded sectional view of an electric hammer principal part concerning Embodiment 2 of the present invention.

Explanation of symbols

1 Electric hammer (power tool)
2 Tool holder 3 Tip tool 4 Cylinder crankcase 5 Motor housing 6 Side handle 7 Handle 8 Switch 9 Electric motor 10 Output shaft (motor shaft) of the electric motor
DESCRIPTION OF SYMBOLS 11 Ball bearing 12 Pinion 13 Cooling fan 14 Crankshaft 14a, 14b Crankshaft through-hole 14c Crankshaft recess 14d Crankshaft rib 15 Ball bearing with seal 16 Needle bearing 17 Gear 18 Crankpin 19 Cylinder 20 Piston 21 Strike 22 Meson 23 Connecting rod 24 Piston pin 25, 26 O-ring 27 Oil seal 28 Communication path forming member 28a Communication path inlet 28b Communication path outlet 29 First filter 30 Second filter 31 Rib 31a Path in rib 32 Communication path S1 Air chamber S2 Mechanism Room (sealed room)
S3 1st passage room S4 2nd passage room

Claims (4)

In a power tool that houses a drive source and a speed reduction mechanism that decelerates rotation of the drive source in a housing, and houses a lubricant in a sealed chamber formed in the housing,
A rotating member that constitutes a part of the speed reduction mechanism is provided, and a through-hole that opens to the sealed chamber and forms a space communicating with the atmosphere is provided inside the rotating member,
In the space of the rotating member, a communication path forming member that is formed of an elastic body and forms a communication path that communicates the atmosphere and the sealed chamber is fitted and rotated integrally with the rotating member,
A power tool characterized in that the communication passage forming member has a passage which forms a part of the communication passage, and a rib whose open end on the closed chamber side protrudes from the periphery is formed . The power tool according to claim 1, wherein a filter is provided in the communication path. The power tool according to claim 2, wherein the filter is provided on both sides of the communication path. The rotating member, the power tool according to any one of claims 1 to 3, characterized in that a crankshaft which constitutes a part of the reciprocation converting mechanism.

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