Patent Application
20190152039
The present invention relates to an impact tool configured to linearly drive a tool accessory in a prescribed hammering-axis direction.
An impact tool is known which is configured to linearly drive a tool accessory in an axial direction by intermittently striking an end of the tool accessory to thereby perform a processing operation on a workpiece. In such an impact tool, noise may arise due to vibration, which is caused by striking the tool accessory. Therefore, for example, patent document 1 discloses a structure for reducing noise which is caused when the tool accessory swings in a radial direction by reaction force from the workpiece and collides with a tool holder.
Patent Document 1: Japanese laid-open patent publication No. 2010-142916
The impact tool disclosed in patent document 1 realizes reduction of noise to some extent by suppressing the swing of the tool accessory in the radial direction. In order to improve an working environment, however, further noise reduction is desired.
It is an object of the present invention to provide a technology which helps reduce noise in an impact tool configured to linearly drive a tool accessory in a prescribed hammering-axis direction.
According to one aspect of the present invention, an impact tool is provided which is configured to linearly drive a tool accessory in a prescribed hammering-axis direction. The impact tool includes a tool-accessory holding part, a body and a first hammering member.
The tool-accessory holding part has a through hole extending in the hammering-axis direction, and is configured to hold the tool accessory inserted into the through hole so as to be movable in the hammering-axis direction. The body is connected to the tool-accessory holding part in the hammering-axis direction. The body has an internal space which communicates with the through hole. The first hammering member is disposed to be linearly movable in the hammering-axis direction and configured to drive the tool accessory in the hammering-axis direction by colliding with the tool accessory. The tool-accessory holding part and the body are connected in the hammering-axis direction via a first elastic element so as to be movable relative to each other. Further, a second elastic element is interposed between the first hammering member and the body in a radial direction with respect to the hammering axis.
In the impact tool in which the first hammering member is configured to drive the tool accessory by colliding with the tool accessory, vibration of the tool accessory which is caused by striking the tool accessory is transmitted to the tool-accessory holding part. If this vibration is further transmitted to the body having the internal space, noise is liable to increase. In order to cope with this, connecting the tool-accessory holding part and the body in the hammering-axis direction via the first elastic element so as to be movable relative to each other can suppress transmission of the vibration from the tool-accessory holding part to the body. Further, like the tool accessory, the first hammering member also generates vibration due to impact of collision. In order to cope with this, the second elastic member which is interposed between the first hammering member and the body in the radial direction can suppress transmission of the vibration from the first hammering member to the body in the radial direction. By thus suppressing the transmission of the vibration from the tool accessory and the first hammering member to the body, noise which might otherwise arise from the vibration of the body can be reduced.
It is noted, in a case where the body has an outer surface directly exposed to the outside, that is, a contact surface with outside air (especially in a case where the outer surface is relatively large), the outer surface is liable to increase the noise by vibrating the air. Further, in a case where the body is formed of metal, this tendency is more apparent. In terms of these points, examples of the body may include an outer exposed part having an outer surface directly exposed to the outside (a contact surface with outside air), and an outer exposed part formed of metal. A typical example of the outer exposed part may be a cylindrical part which houses the first hammering member configured to drive the tool accessory and a driving element (typically, a piston or a piston cylinder) configured to linearly move the first hammering member.
According to one aspect of the impact tool of the present invention, a portion of the tool-accessory holding part may be disposed between the first hammering member and the body in the radial direction. The second elastic element may be disposed between the portion of the tool-accessory holding part and the body, In a case where a portion of the tool-accessory holding part is disposed between the first hammering member and the body in the radial direction, vibration transmitted from the tool accessory to the tool-accessory holding part and vibration transmitted from the hammering member to the tool-accessory holding part may be transmitted to the body in the radial direction. To cope with this, the second elastic element which is disposed between the portion of the tool-accessory holding part and the body can effectively suppress the transmission of the vibration to the body and thereby reduce noise.
According to one aspect of the impact tool of the present invention, the first elastic element may be rubber. Further, the first elastic element may be interposed between the tool-accessory holding part and the body so as to be compressed when the tool-accessory holding part and the body relatively move in either direction toward or away from each other in the hammering-axis direction. Generally, rubber has higher bearing force in a compression direction than in a tensile direction. Therefore, by configuring the first elastic clement formed of rubber such that the first elastic element is compressed when the tool-accessory holding part and the body relatively move in either direction toward or away from each other, durability of the first elastic element can be favorably maintained.
According to one aspect of the impact tool of the present invention, the impact tool may further include a first member and a second member. The first member may be fixed to the tool-accessory holding part and may be disposed between the tool-accessory holding part and the body in the hammering-axis direction. The second member may be fixed to the body and may be disposed between the tool-accessory holding part and the first member in the hammering-axis direction. Further, at least a portion of the first elastic element may be interposed between the first member and the second member. In this case, the first elastic element can be configured such that a pardon of the first elastic element which is interposed between the tool-accessory holding part and the body is compressed when the tool-accessory holding part and the body relatively move toward each other, while another portion of the first elastic element which is interposed between the first member and the second member is compressed when the tool-accessory holding part and the body relatively move away from each other.
According to one aspect of the impact tool of the present invention, the tool-accessory holding part may include a cylindrical slide-guide member which is configured to slidably guide the first hammering member in the hammering-axis direction. The first member may be integrally formed with the slide-guide member. Generally, the tool-accessory holding part includes a slide-guide member. Therefore, in a case where the slide-guide member and the first member are integrally formed as a single member, assembling efficiency can be improved and the number of components can be reduced, as compared with a case where the first member is formed as a separate member from the sliding guide member.
According to one aspect of the impact tool of the present invention, the impact tool may further include a plurality of first members and a plurality of second members. The plurality of first members may be fixed to the tool-accessory holding part and may be disposed between the tool-accessory holding part and the body in the hammering-axis direction. The plurality of second members may be fixed to the body and may be disposed between the tool-accessory holding part and the plurality of first members in the hammering axis-direction. The plurality of first members and the plurality of second members may be alternately arranged in a circumferential direction around the hammering axis. Further, at least a portion of the first elastic element may be interposed between the plurality of first members and the plurality of second members. In this case, the first elastic element can be configured such that a portion of the first elastic element which is interposed between the tool-accessory holding part and the body is compressed when the tool-accessory holding part and the body relatively move toward each other, while another portion of the first elastic element which is interposed between the first members and the second members is compressed when the tool-accessory holding part and the body relatively move away from each other. Furthermore, the tool-accessory holding part and the body can move relative to each other in a well-balanced manner along the hammering axis.
According to one aspect of the impact tool of the present invention, the impact tool may further include a circular cylindrical member and a second hammering member. The circular cylindrical member may be disposed coaxially with the hammering axis, in the internal space of the body. The second hammering member may be disposed to be movable in the hammering-axis direction within the circular cylindrical member and may be configured to linearly move the first hammering member by colliding with the first hammering member. Further, the second hammering member may have a circular column part having a circular column shape, and the second hammering member may have one or more third elastic elements disposed on an outer circumferential surface of the circular column part. The one or more third elastic elements may be slidable in the hammering-axis direction along an inner circumferential surface of the circular cylindrical member, and may be configured to hold the second hammering member within the circular cylindrical member in a state in which the outer circumferential surface of the second hammering member is not in contact with the inner circumferential surface of the circular cylindrical member. Vibration is also caused in the second hammering member when the second hammering member moves and collides with the first hammering member within the circular cylindrical member disposed in the internal space of the body. In order to cope with this, the one or more third elastic elements on the outer circumferential surface of the second hammering member which hold the second hammering member in a non-contact state with respect to the inner circumferential surface of the circular cylindrical member can suppress transmission of the vibration from the second hammering member to the circular cylindrical member and thus to the body and reduce noise.
According to one aspect of the impact tool of the present invention, the second hammering member may be configured to be moved in the hammering-axis direction within the circular cylindrical member by pressure fluctuations of air in an air chamber formed in the circular cylindrical member. At least one of the one or more third elastic elements may have an annular shape to surround a whole circumference of the outer circumferential surface of the second hammering member and may also serve as a sealing member for the air chamber. In this case, it is not necessary to additionally and separately provide a sealing member which is required to maintain airtightness of the air chamber in a structure using air pressure fluctuations of the air chamber to move the second hammering member.
According to one aspect of the impact tool of the present invention, the first elastic element and the second elastic element may be integrally formed as a single elastic member. In this case, compared with a case in which the first and second elastic elements are separately formed, assembling efficiency can be improved and the number of components can be reduced.
According to one aspect of the impact tool of the present invention, the first elastic element may be rubber and an outer circumferential surface of the first elastic element may be covered. Since the first elastic element connects the body and the tool-accessory holding part in the hammering-axis direction, the outer surface of the first elastic element in the hammering-axis direction is likely to be in contact with the body, the tool-accessory holding part or another member, while the outer circumferential surface (an outer surface on the radially outer side) of the first elastic element is likely to be exposed to the outside. According to the present aspect, however, deterioration of the first elastic element can be suppressed which might otherwise be caused by exposure to dust generated during the processing operation of the tool accessory. It is noted that the outer circumferential surface of the first elastic clement may be covered by either one or both of the body and the tool-accessory holding part. Alternatively, the outer circumferential surface of the first elastic element may be covered by a member other than the body and the tool-accessory holding part.
An embodiment of the present invention is now described with reference to the drawings. In the present embodiment, an electric hammer 1 (hereinafter simply referred to as a hammer 1) is described as an example of an impact tool which is configured to linearly drive a tool accessory in a prescribed hammering-axis direction.
First, the general structure of the hammer 1 is described with reference to
The tool holder 6 is configured to detachably hold a tool accessory 9 (typically, a hammer bit). The hammer 1 of the present embodiment is configured to perform an operation (a hammering operation) of linearly driving the tool accessory 9 coupled to the tool holder 6 along the hammering axis A1. A user may select the tool accessory 9 of an appropriate kind according to a processing operation to be actually performed and attach the tool accessory 9 to the tool holder 6 such that an axial direction of the tool accessory 9 coincides with the hammering axis A1. The hammer 1 may perform a chipping operation on a workpiece by the hammering operation.
A pair of handles 16 are provided on the body 10 on the opposite side of the tool holder 6 with respect to the barrel 12 in the hammering-axis A1 direction. The handles 16 are symmetrically arranged with respect to the hammering axis A1 and protrude from the body 10 in a direction generally orthogonal to the hammering axis A1. The hammer 1 of the present embodiment is configured as a large hammer having a weight of about 30 kg. Generally, the user may use the hammer 1 while holding the handles 16 with both hands, with the tool accessory 9 coupled to the tool holder 6 protruding downward. Therefore, in the following description, for convenience of explanation, the hammering-axis A1 direction (also referred to as a longitudinal-axis direction of the body 10 or an axial direction of the tool accessory 9) is defined as an up-down direction of the hammer 1. In the hammering-axis A1 direction, the side of the tool holder 6 is defined as a lower side and the side of the handles 16 is defined as an upper side. Further, the extending direction of the handles 16 is defined as a left-right direction.
The detailed structure of the hammer 1 is now described. First, the structure of the body 10 is described with reference to
As shown in
The outer housing 15 is arranged outside the body housing 11 so as to cover the body housing 11. Each of the handles 16 is arranged in a cantilevered form, with one end of the handle 16 fixed to the outer housing 15. One of the handles 16 has an electric switch 161 and a trigger 162 for switching on and off the electric switch 161. Further, although not described in detail, an upper portion of the outer housing 15 including the handles 16 is connected to the body housing 11 via an elastic element so as to be movable in the hammering-axis A1 direction (up-down direction) relative to the body housing 11. Such a structure can suppress transmission of vibration from the body housing 11 to the handles 16.
The barrel 12 has an elongate circular cylindrical shape as a whole. As shown in
Four second threaded holes 125 are formed in a lower end portion of the barrel 12 (specifically, the flange 132 and the large-diameter part 122) and arranged at equal intervals in a circumferential direction. Each of the second threaded holes 125 is configured such that a second screw 87, which will be described later, can be threadably engaged therewith.
As shown in
In the present embodiment, an alternate current (AC) motor is employed as the motor 2 which serves as a driving source for the tool accessory 9. The motor 2 may be driven by power supply from an external AC power source via a power cable 19 (see
The first motion converting mechanism 3 is configured to convert rotation of the output shaft 21 of the motor 2 into linear motion and to transmit it to a striking mechanism 5, which will be described later. In the present embodiment, the first motion converting mechanism 3 is configured to convert rotation of the output shaft 21 into reciprocating motion of a piston 37 to thereby linearly drive a striker 51 in the hammering-axis A1 direction within the cylinder 50. The structure of the first motion converting mechanism 3 is known and therefore only briefly described here. As shown in
The second motion converting mechanism 4 is configured to convert rotation of the output shaft 21 of the motor 2 into reciprocating motion of a counterweight 47. The structure of the second motion converting mechanism 4 is also known and therefore only briefly described here. As shown in
The structure of the tool holder 6 is now described with reference to
The body 60 includes a small-diameter part 61 which forms a lower portion of the body 60, a large-diameter part 62 which forms an upper portion of the body 60 and which has a larger diameter than the small-diameter part 61, and a stepped part 63 which connects the small-diameter part 61 and the large-diameter part 62. A flange 64 is formed on the upper end of the large-diameter part 62 and protrudes radially outward. The flange 64 has substantially the same diameter as the flange 132 of the outer sleeve 13. As shown in
The inner sleeve 7 has a circular cylindrical shape and is integrally fixed to the body 60 in a state in which its lower portion is fitted in an upper portion of the large-diameter part 62, coaxially with the hammering axis A1. A portion of the inner sleeve 7 which protrudes upward from the large-diameter part 62 is referred to as a protruding part 73. O-rings 75, which are elastic elements, are fitted on an outer circumferential surface of the protruding part 73. More specifically, four O-rings 75 are respectively fitted in four grooves which are annularly formed in the outer circumferential surface of the protruding part 73. A rubber ring 67, which is an elastic element, is disposed inside a lower end portion of the large-diameter part 62. More specifically, the rubber ring 67 is held between the stepped part 63 and a washer 68 disposed under the inner sleeve 7 in the hammering-axis A1 direction (up-down direction) and prevented from moving in the hammering-axis A1 direction. The hole diameter of the rubber ring 67 is set to be generally equal to the diameter of a base end portion of the tool accessory 9 (an end portion opposite to a tip end portion of the tool accessory 9 which performs a processing operation on a workpiece).
It is noted that a portion of the through hole 65 which extends inside the small-diameter part 61 forms a tool insertion hole 651, through which a shank of the tool accessory 9 having a polygonal section is inserted, and has a sectional shape corresponding to the shank. Rotation of the tool accessory 9 relative to the tool holder 6 can be prevented by fitting the shank of the tool accessory 9 in the tool insertion hole 651. An upper portion of the through hole 65 above the tool insertion hole 651 extends through the rubber ring 67, the washer 68 and the inner sleeve 7, and communicates with the internal space of the barrel 12. It is noted that, when the shank is inserted through the tool insertion hole 651, the base end portion of the tool accessory 9 is disposed within the hole of the rubber ring 67.
As shown in
First, the structure of connecting the barrel 12 and the tool holder 6 in the radial direction is described. As shown in
The structure of connecting the barrel 12 and the tool holder 6 in the hammering-axis A1 direction is now described with reference to
As shown in
As shown in
As shown in
As shown in
As shown in
The first and second members 81, 82 configured as described above are assembled to the connecting rubber 80 to form the connection part 8. Specifically, the first members 81 are fitted in the first-member receiving parts 801 from above and the second members 82 are fitted in the second-member receiving parts 806, so that the connection part 8 is formed as one unit. Subsequently, as shown in
When the barrel 12 and the tool holder 12 are connected to each other via the connection part 8 as described above, the connecting rubber 80 is sandwiched between the barrel 12 and the tool holder 12 (more specifically, between the flange 132 and the flange 64) in the hammering-axis A1 direction, Further, the first compression parts 811 of the first members 81 and the second compression parts 821 of the second members 82 are arranged to partly overlap in the hammering-axis A1 direction (up-down direction). More specifically, as shown in
With such an arrangement, when the barrel 12 and the tool holder 6 relatively move toward each other, the portions of the connecting rubber 80 which are interposed between the barrel 12 and the tool holder 6 (more specifically, between the flange 132 and the flange 64) are compressed. On the other hand, when the barrel 12 and the tool holder 6 relatively move away from each other, the portions of the connecting rubber 80 which are interposed between the first compression parts 811 and the second compression parts 821 are compressed. Thus, the connecting rubber 80 is interposed between the barrel 12 and the tool holder 6 so as to be compressed not only when the barrel 12 and the tool holder 6 relatively move in a direction toward each other, but also when the barrel 12 and the tool holder 6 relatively move in a direction away from each other.
The structure of the striking mechanism 5 is now described with reference to
As shown in
The striker 51 is configured to linearly move the impact bolt 53 by colliding with the impact bolt 53. As shown in
As shown in
The impact bolt 53 is disposed to be linearly movable in the hammering-axis A1 direction, and configured to drive the tool accessory 9 in the hammering-axis A1 direction by colliding with the tool accessory 9. As shown in
It is noted that, as shown in
Operations of the hammer 1 having the above-described structure and operations of the various elastic elements (the connecting rubber 80, the O-rings 75, the O-rings 512, the rubber ring 67, the rubber ring 541) of the hammer 1 are now described.
User holds the handle 16, pushes down the body 10 and presses the tool accessory 9 against a workpiece. Then, the impact bolt 53 is pushed upward together with the tool accessory 9, an upper end of the central part 533 abuts on the washer 543 and is elastically held by the rubber ring 541. Thus, the impact bolt 53 is prevented from further moving upward, so that the body 10 is positioned with respect to the workpiece in the hammering-axis A1 direction.
When the trigger 162 is depressed and the motor 2 is driven, the piston 37 is caused to reciprocally slide within the cylinder 50 by the first motion converting mechanism 3. As a result, pressure fluctuations of the air in the air chamber 55 occur, and thereby cause the striker 51 to linearly move. Specifically, when the piston 37 is moved downward, the air in the air chamber 55 is compressed so that the internal pressure increases. Therefore, the striker 51 is pushed downward at high speed, in a state in which the O-rings 512 slide along the inner circumferential surface of the cylinder 50, and collides with the impact bolt 53.
When the striker 51 collides with the impact bolt 53, the impact bolt 53 moves downward and collides with the tool accessory 9, so that the kinetic energy of the striker 51 is transmitted to the tool accessory 9. Then, the tool accessory 9 is linearly driven along the hammering axis A1 and strikes the workpiece. On the other hand, when the piston 37 is moved upward by the first motion converting mechanism 3, the air in the air chamber 55 expands so that the internal pressure decreases and the striker 51 is retracted upward. By thus repeating the hammering operation, the hammer 1 performs the chipping operation on the workpiece.
During the chipping operation, vibration is caused in the tool accessory 9 due to impact of collision of the impact bolt 53 and reaction force from the workpiece. The vibration of the tool accessory 9 is directly transmitted to the tool holder 6 which holds the tool accessory 9. The barrel 12 connected to an upper portion of the tool holder 6 has a circular cylindrical shape having an internal space. In such a structure, if the vibration of the tool holder 6 is transmitted to the barrel 12, noise is liable to increase. Further, the barrel 12 has a relatively large outer surface which is exposed to the outside and is formed of metal. Consequently, the noise is especially liable to increase.
In order to cope with this, in the present embodiment, the tool holder 6 and the barrel 12 are connected in the hammering-axis A1 direction via the connecting rubber 80, which is an elastic element, so as to be movable relative to each other. Among vibrations caused in the hammer 1 in which the tool accessory 9 is linearly driven in the hammering-axis A1 direction, vibration in the hammering-axis A1 direction is the largest and most dominant. By provision of the above-described structure, the tool holder 6 and the barrel 12 can move relative to each other in the same direction as this vibration, so that transmission of this vibration from the tool holder 6 to the barrel 12 can be effectively suppressed. Further, vibration is also caused in the impact bolt 53 due to the impact of collision with the tool accessory 9. In order to cope with this, in the present embodiment, the O-rings 75, which are elastic elements, are interposed between the impact bolt 53 and the barrel 12 in the radial direction with respect to the hammering axis A1. In other words, the impact bolt 53 and the barrel 12 are elastically connected in the radial direction via the O-rings 75 (elastic elements). Such a structure can suppress transmission of the vibration from the impact bolt 53 to the barrel 12 in the radial direction. By thus suppressing the transmission of the vibrations from the tool accessory 9 and the impact bolt 53 to the barrel 12, noise which might otherwise arise from vibration of the barrel 12 can be reduced.
Further, like in the present embodiment, in a structure in which a portion (specifically, the inner sleeve 7) of the tool holder 6 is disposed between the impact bolt 53 and the barrel 12 (specifically, the outer sleeve 13) in the radial direction, the vibration transmitted from the tool accessory 9 to the tool holder 6 and the vibration transmitted from the impact bolt 53 to the tool holder 6 may be transmitted to the barrel 12 in the radial direction. In order to cope with this, in the present embodiment, the O-rings 75 are interposed between the portion (the inner sleeve 7) of the tool holder 6 and the barrel 12 (the outer sleeve 13) to elastically connect them., so that transmission of the vibration to the barrel 12 can be further effectively suppressed and noise can be reduced. Further, the protruding part 73 of the inner sleeve 7 is formed to be relatively long with respect to the whole length of the tool holder 6 in the hammering axis A1 direction, and almost the whole protruding part 73 is connected to the inside of the cylindrical part 131 of the outer sleeve 13 via the O-ring 75. Therefore, sufficient resistance against bending moment can be maintained.
As described above, in the hammer 1, the vibration in the hammering-axis A1 direction is the largest and most dominant. In order to cope with this, the connecting rubber 80 is interposed between the barrel 12 and the tool holder 6 such that the connecting rubber 80 is compressed when the barrel 12 and the tool holder 6 relatively move in either direction toward or away from each other in the hammering-axis A1 direction. Generally, rubber has higher bearing force in a compression direction than in a tensile direction. Therefore, with such a structure, durability of the connecting rubber 80 can be favorably maintained.
In the present embodiment, the connecting rubber 80 is held between the tool holder 6 and the barrel 12 by the first members 81 and the second members 82, such that the connecting rubber 80 is partly interposed between the first compression parts 811 and the second compression parts 821 in the hammering-axis A1 direction. With this structure, the connecting rubber 80 can be compressed when the barrel 12 and the tool holder 6 relatively move in either direction toward or away from each other. Further, the four first members 81 and the four second members 82 are alternately arranged in the circumferential direction around the hammering axis A1. Therefore, the tool holder 6 and the barrel 12 can move relative to each other in a well-balanced manner along the hammering axis A1.
The hammer 1 of the present embodiment has the cylinder 50 disposed in the internal space of the barrel 12 and is configured such that the columnar striker 51 disposed within the cylinder 50 collides with the impact bolt 53. The striker 51 can move within the cylinder 50 while being held in a non-contact state with respect to the inner circumferential surface of the cylinder 50 by the two O-rings 512, which are slidable in the hammering-axis A1 direction along the inner circumferential surface of the cylinder 50. Vibration is also caused in the striker 51 when the striker 51 collides with the impact bolt 53. In order to cope with this, the two O-rings 512, which are elastic elements, are provided to prevent the striker 51 from tilting with respect to the hammering axis A1 while moving, and and also to suppress transmission of the vibration from the striker 51 to the cylinder 50 and thus to the barrel 12 and reduce the noise. The O-ring 512 is a holding member for holding the striker 51 as described above, and also serves as a sealing member for maintaining airtightness of the air chamber 55 Therefore, it is not necessary to additionally and separately provide a sealing member which is required for a structure using pressure fluctuations of the air in the air chamber 55 to move the striker 51.
In a case where a known structure is employed in which the outer circumferential surface of the striker 51 slides along the inner circumferential surface of the cylinder 50, it is necessary to polish the outer circumferential surface of the striker 51 so as to make the diameter of the striker 51 substantially equal to the inner diameter of the cylinder 50. However, in a structure in which the diameter of the striker 51 is smaller than the inner diameter of the cylinder 50 and the striker 51 is moved by the sliding movement of the O-rings 512, like in the present embodiment, such a strict dimensional accuracy is not required for the striker 51, which facilitates manufacturing the striker 51.
The rubber ring 67 disposed within the lower end portion of the large-diameter part 62 of the tool holder 6 elastically holds the base end portion of the tool accessory 9 disposed within the tool holder 6 and thereby suppresses a radial swinging movement of the tool accessory 9 which is caused by reaction force froth the workpiece. Thus, vibration and noise which might be otherwise caused by collision of the tool accessory 9 with the tool holder 6 can be reduced.
The rubber ring 541 is held between the lower end of the cylinder 50 disposed within the barrel 12 and the upper end of the tool holder 6 (the inner sleeve 7). Therefore, when the tool holder 6 and the barrel 12 move in the hammering-axis A1 direction relative to each other, the rubber ring 541 can suppress transmission of the vibration of the tool holder 6 to the cylinder 50 and thus to the barrel 12 and thereby reduce noise.
Correspondences between the features of the embodiment and the features of the invention are as follows. The hammer 1 is an example that corresponds to the “impact tool” according to the present invention. The tool holder 6 is an example that corresponds to the “tool-accessory holding part” according to the present invention. The barrel 12 is an example that corresponds to the “body” according to the present invention. The impact bolt 53 is an example that corresponds to the “first hammering member” according to the present invention. The connecting rubber 80 is an example that corresponds to the “first elastic element” according to the present invention. The O-ring 75 is an example that corresponds to the “second elastic element” according to the present invention. The first member 81 and the second member 82 are examples that correspond to the “first member” and the “second member”, respectively, according to the present invention. The cylinder 50 is an example that corresponds to the “circular cylindrical member” according to the present invention. The striker 51 is an example that corresponds to the “second hammering member” according to the present invention. The O-ring 512 is an example that corresponds to the “third elastic element” according to the present invention.
The above-described embodiment is a mere example and an impact tool according to the present invention is not limited to the structure of above-described the hammer 1. For example, the following modifications may be made. Note that one or more of these modifications may be employed in combination with the hammer 1 of the above-described embodiment or the invention as defined in any one of the claims.
For example, in the above-described embodiment, a portion (the inner sleeve 7) of the tool holder 6 is disposed between the impact bolt 53 and the barrel 12 (the outer sleeve 13), and the O-rings 75 (elastic elements) are interposed between the inner sleeve 7 and the outer sleeve 13. However, the arrangement relation between the impact bolt 53, the tool holder 6 and the barrel 12 may be appropriately changed, as long as an elastic element is interposed between the impact bolt 53 and the barrel 12 in the radial direction with respect to the hammering axis A1.
For example, in a hammer 101 according to a modification shown in
Further, in an impact bolt 530 of the present modification, unlike in the above-described embodiment, the diameter of a central part 535 is slightly smaller than the inner diameter of the inner sleeve 70. An O-ring 537 and a slide ring 538 are fitted on an outer circumferential surface of the central part 535. More specifically, three annular grooves are formed in the outer circumferential surface of the central part 535, and the O-ring 537 and the slide ring 538, which are both elastic elements, are respectively fitted in uppermost and lowermost ones of the three grooves. The O-ring 537 and the slide ring 538 on the impact bolt 530 can slide in the hammering-axis A1 direction along an inner circumferential surface of the inner sleeve 70. Further, the O-ring 537 and the slide ring 538 hold the impact bolt 530 within the inner sleeve 70 in a state in which the outer circumferential surface of the impact bolt 530 is not in contact with the inner circumferential surface of the inner sleeve 70.
In the present modification, when vibration is caused in the impact bolt 530 due to the impact of collision with the tool accessory 9, the O-ring 537 and the slide ring 538 can suppress transmission of the vibration from the impact bolt 530 to the tool holder 600 (the inner sleeve 70) and thereby reduce transmission of the vibration to the barrel 120 and thus reduce noise. Further, like the striker 51 of the above-described embodiment, the impact bolt 530 does not require strict dimensional accuracy, which facilitates remanufacturing the impact bolt 530.
In the present modification, the tool holder 600 is an example that corresponds to the “tool-accessory holding part” according to the present invention. The barrel 120 is an example that corresponds to the “body” according to the present invention. The impact bolt 530 is an example that corresponds to the “first hammering member” according to the present invention, Each of the O-ring 537 and the slide ring 538 is an example that corresponds to the “second elastic element” according to the present invention.
Further, for example, in a structure in which no portion of the tool holder 600 is interposed between the impact bolt 530 and the barrel 120, and the impact bolt 530 can slide within the barrel 120, like in the modification shown in
In the above-described embodiment and modifications, a plurality of elastic elements (the four O-rings 75, the O-ring 537 and the slide ring 538) are interposed between the impact bolt 53, 530 and the barrel 12, 120 in the radial direction, but the number of the elastic elements interposed between the impact bolt 53, 530 and the barrel 12, 120 may be changed. In the modification shown in
Likewise, the number of the O-rings 512 for the striker 51 is not limited to two, and only one O-ring 512, or three or more O-rings 512 may be used. In order to avoid the striker 51 from tilting with respect to the hammering axis A1 while moving, however, like those for the impact bolt 530 as described above, it may be preferable to employ an O-ring 512 which is formed wider to some extent, or to employ a plurality of O-rings 512 which are arranged at plural positions in the hammering-axis A1 direction. Further, the elastic element which serves to hold the striker 51 in a state in which the outer circumferential surface of the striker 51 is kept in a non-contact state with respect to the inner circumferential surface of the cylinder 50 does not need to also serve as a sealing member for the air chamber 55. In a case where a plurality of elastic elements are provided, at least one of the elastic elements may also serve as the sealing member for the air chamber 55. For example, an uppermost one (on the air chamber 55 side) of the elastic elements may be the O-ring 512, and other elastic elements may be fixed to the outer circumferential surface of the striker 51 at plural positions in the circumferential direction on the lower side of the uppermost one.
The striker 51 does not need to be formed in a circular column shape as a whole, and may include a portion which is formed in a circular column shape. For example, the front end portion of the striker 51 which collides with the impact bolt 53, 530 may have a smaller diameter than the body having a circular column shape. Further, in place of the striker 51, a conventional striker configured such that its outer circumferential surface slides along the inner circumferential surface of the cylinder 50 may be employed, as the second hammering member for driving the impact bolt 53, 530.
The structure of connecting the tool holder 6 and the barrel 12 in the hammering-axis A1 direction so as to be movable relative to each other is not limited to the connection part 8 including the connecting rubber 80. For example, the tool holder 6 and the barrel 12 may be connected via a spring, which is an elastic element, so as to be movable relative to each other in the hammering-axis A1 direction, Further, the connection part 8 includes the four first members 81 and the four second members 82, but their shapes, numbers and arrangement positions relative to the connecting rubber 80 may be appropriately changed. In order to realize a structure in which the elastic element can be compressed when the barrel 12 and the tool holder 6 relatively move in either direction toward or away from each other, however, it may be preferable that the first member 81 fixed to the tool holder 6 and the second member 82 fixed to the barrel 12 are configured such that at least a portion of the second member 82 is disposed between the tool holder 6 and at least a portion of the first member 81. Further, the barrel 12 and the tool holder 6 may be provided with respective structures of holding the elastic element, in place of the first and second members 81, 82.
A hammer 102 having an exemplary connection structure in place of the connection part 8 is now described with reference to
First, the structure of the barrel 14 is described. As shown in
The structure of the tool holder 605 is now described. As shown in
As shown in
The structure of connecting the barrel 14 and the tool holder 605 is now described. In the present modification, the barrel 14 and the tool holder 605 are connected to each other via a connecting rubber 83, the above-described connecting flange 704 of the inner sleeve 700 and a retainer ring 84.
As shown in
As shown in
The barrel 14 and the tool holder 605 are connected as follows via the connecting rubber 83, the connecting flange 704 and the retainer ring 84 which are configured as described above.
As shown in
In the present modification, only the rubber ring 67 is disposed within the body 60 (the large-diameter part 62) of the tool holder 605, and a lower end of the inner sleeve 70 is held in direct contact with the rubber ring 67 without a washer. In order to provide a larger contact surface between the inner sleeve 700 and the rubber ring 67, however, like in the above-described embodiment, a washer may be disposed between the inner sleeve 700 and the rubber ring 67. Further, in place of the rubber ring 67, an elastic element formed of a different elastic material (such as urethane) may be employed.
After positioning as describe above, each of the four first screws 860 is inserted through the through hole 641, the through hole 842 and the through hole 835 in this order from below the flange 64 and threadably engaged with the first threaded hole 707 of the screw fastening part 706 of the connecting flange 704, so that the inner sleeve 700 is fixed to the body 60. It is noted that the length of the shaft of the first screw 860 is set such that a tip end of the shaft slightly protrudes from an upper surface of the screw fastening part 706. The shaft of the first screw 860 is loosely disposed in the through hole 842 of the retainer ring 84, and thus the retainer ring 84 is not fixed to the inner sleeve 700 or the body 60.
Subsequently, the four screw fastening parts 143 are positioned to be engaged with the four recesses 836 formed in the outer circumferential portion of the connecting rubber 83, and then the inner sleeve 700 is inserted into the lower end portion of the barrel 14. At this time, the through hole 642 of the flange 64, the through hole 841 of the retainer ring 84 and the second threaded hole 144 of the screw fastening part 143 of the barrel 14 are coaxially aligned in this order from below, Then, each of the four second screws 870 is inserted through the through hole 642 and the through hole 841 from below the flange 64 and threadably engaged with the second threaded hole 144 of the screw fastening part 143, so that the retainer ring 84 is fixed to the barrel 14 (the large-diameter part 142). In this state, the head of the second screw 870 is loosely disposed in the through hole 642 of the flange 64 and is not fixed to the tool holder 605. A clearance between the through hole 642 and the head of the second screw 870 is set such that the second screw 870 fixed to the barrel 64 and the tool holder 605 (the flange 64) are prevented from coming into contact with each other when the barrel 14 and the tool holder 605 move relative to each other in the radial direction.
When the barrel 14 and the tool holder 605 are connected as described above, as shown in
Further, a portion of the connecting rubber 83 is disposed between the barrel 14 and the tool holder 605 (the body 60) in the hammering-axis A1 direction (up-down direction). The connecting flange 704 (the screw fastening part 706) fixed to the tool holder 605 and the retainer ring 84 fixed to the barrel 14 are arranged to partly overlap (be opposed to) each other in the hammering-axis A1 direction (up-down direction), and a portion of the connecting rubber 83 is interposed between these overlapped parts. A clearance is formed between the upper surface of the flange 64 and the lower surface of the retainer ring 84. Similarly, a clearance is also formed between the upper surface of the screw fastening part 706 (and a tip end of the shaft of the first screw 860) and an inner lower end surface 146 of the barrel 14 which is located above the screw fastening part 706. With such an arrangement, the tool holder 605 and the barrel 14 are connected with each other in the hammering-axis A1 direction via the connecting rubber 83 in a state in which he tool holder 605 and the barrel 14 are not in contact with each other.
When the barrel 14 and the tool holder 605 relatively move toward each other, an outer peripheral part 837 of an upper end of the connecting rubber 83 is compressed by the inner lower end surface 146 of the barrel 14. At this time, the O-ring 849 disposed between the retainer ring 84 and the flange 64 is also compressed, but the O-ring 849 prevents the retainer ring 84 and the flange 64 from coming into contact with each other. Further, even when the O-ring 849 is compressed to the maximum, the inner lower end surface 146 does not come into contact with the screw fastening part 706 (and the tip end of the shaft of the first screw 860). On the other hand, when the barrel 14 and the tool holder 605 relatively move away from each other, a portion of the connecting rubber 83 which is interposed between the connecting flange 704 (the screw fastening part 706) and the retainer ring 84 is compressed. Thus, the connecting rubber 83 is interposed between the barrel 14 and the tool holder 605 so as to he compressed when the barrel 14 and the tool holder 605 relatively move in either direction toward or away from. each other.
In the hammer 102 according to the present modification, like in the hammer 1 of the above-described embodiment, transmission of vibration from the tool holder 605 to the barrel 14 both in the hammering-axis A1 direction arid in the radial direction can he effectively suppressed and thus noise which might otherwise arise from the vibration of the barrel 14 can be reduced.
Further, in the present embodiment, the elastic element for elastically connecting the tool holder 605 and the barrel 14 in the hammering-axis A1 direction and the elastic element for elastically connecting the tool holder 605 and the barrel 14 in the radial direction are integrally formed as a single elastic member, that is, the connecting rubber 83. This structure can improve assembling efficiency and reduce the number of components. Further, also by providing the connecting flange 704 (the screw fastening parts 706), in place of the first members 81 of the above-described embodiment, which is integrally formed with the cylindrical part 701 of the inner sleeve 700, improvement of assembling efficiency and reduction of the number of components can be realized. Further, the retainer ring 84 provided in place of the second members 82 of the above-described embodiment is a single member, but can be opposed to the connecting flange 704 (the screw fastening parts 706) at plural positions in the circumferential direction. With such a structure, when the barrel 14 and the tool holder 605 relatively move away from each other, the connecting rubber 83 can he compressed at plural positions in the circumferential direction. Thus, according to the present modification, a simpler and more effective connecting structure is realized.
Further, in the present modification, the outer circumferential surface of the connecting rubber 83 is covered by the barrel 14, which can suppress deterioration of the connecting rubber 83 due to exposure to dust generated during the chipping operation. Further, in the present modification, not only the outer circumferential surface, but also other parts of the connecting rubber 83 are covered by the retainer ring 84 and the flange 64, so that deterioration of the connecting rubber 83 can be further effectively suppressed.
Correspondences between the features of the present modification and the features of the present invention are as follows. The hammer 102 is an example that corresponds to the “impact tool” according to the present invention. The tool holder 605 is an example that corresponds to the “tool-accessory holding part” according to the present invention. The barrel 14 is an example that corresponds to the “body” according to the present invention. The impact bolt 56 is an example that corresponds to the “first hammering member” according to the present invention. The connecting rubber 83 is an example that corresponds to each of the “first elastic element” and the “second elastic element” and the “single elastic member” according to the present invention. The connecting flange 704 and the retainer ring 84 are examples that correspond to the “first member” and the “second member”, respectively, according to the present invention. The cylindrical part 701 of the inner sleeve 700 is an example that corresponds to the “slide-guide member” according to the present invention. Further, as a matter of course, like the connecting structure of the above-described embodiment, the connecting structure of the present modification can be appropriately changed.
In the above-described embodiment and modifications, the electric hammer 1, 101, 102 which is capable of performing only the hammering operation is described as an example of the impact tool, but the impact tool may be a hammer drill which is capable of performing a drilling operation of rotationally driving the tool accessory 9, in addition to the hammering operation. Further, in the above-described embodiment and modifications, the striker 51 is configured to linearly move the tool accessory 9 in the hammering-axis A1 direction by linearly moving and indirectly colliding with an axial one end (rear end) of the tool accessory 9 via the impact bolt 53, 530, 56. However, the striker 51 may be configured to move the tool accessory 9 by directly colliding with the end of the tool accessory 9. In this case, the striker 51 corresponds to the “first hammering member” according to the present invention. Further, the striker 51 does not need to be driven by the piston 37 which reciprocates within the cylinder 50, and may be driven by a bottomed cylindrical piston-cylinder which reciprocates in the hammering-axis A1 direction.
The arrangements and the structures of the motor 2 and the first motion converting mechanism 3 are not limited to those of the above-described embodiment. For example, a direct current motor may be employed in place of the motor 2. In place of the first motion converting mechanism 3, any structure may be employed which is capable of converting rotation of the motor into reciprocating motion of the piston 37 or a piston-cylinder. Further, the impact tool is not limited to that which is powered by the motor 2. For example, the impact tool may be powered by compressed air generated by an air compressor and provided with a driving mechanism configured to linearly move the striker 51 which is slidably arranged within the cylinder 50 in the hammering-axis A1 direction. The hammer 1, 101, 102 does not need to have the second motion converting mechanism 4 and may have a different vibration-proofing mechanism.
A portion of the impact tool to which the tool holder 6 for holding the tool accessory 9 is connected in the hammering-axis A1 direction via the elastic element does not need to have a circular cylindrical shape like the barrel 12, as long as the portion has an internal space which communicates with the through hole 65 of the tool holder 6. In an impact tool which is configured to linearly drive the tool accessory 9 in the hammering-axis A1 direction via the striker 51, however, the cylinder 50 or a piston-cylinder having a circular cylindrical shape is typically employed to linearly drive the striker 51. In such a case, it is quite common that a portion of the impact tool which houses the cylinder 50 or the piston-cylinder has a cylindrical (tubular) shape (not limited to a circular cylindrical shape) having a relatively large internal space (in which no parts are disposed) compared with other portions. Further, a clearance is often provided particularly between the portion which houses the cylinder 50 or the piston-cylinder and the cylinder 50 or the piston cylinder. In such a case, noise may further increase. In view of this, the following features are provided. One or more of the features can be employed in combination with any one of the hammer drills 1, 101, 102 of the embodiment and the modifications, or in combination with any one of the claimed inventions.
The body may include a cylindrical-member housing part having a cylindrical shape and housing a circular cylindrical member disposed coaxially with the hammering axis, and the cylindrical-member housing part and the tool-accessory holding part of the body may be connected in the hammering-axis direction via the first elastic element so as to be movable relative to each other.
In aspect 1 above, a clearance nay be provided between the cylindrical-member housing part and the circular cylindrical member.
In aspect 1 or 2 above, the circular cylindrical member may have an air chamber of which air pressure fluctuations are utilized to drive the first hammering member.
In any one of aspects 1 to 3 above, the body may include a driving-mechanism housing part which houses a driving mechanism configured to linearly move the first hammering member.
In any one of aspects 1 to 4 above, an elastic element may be interposed between the tool-accessory holding part and the circular cylindrical member.
The single elastic member may be cylindrically shaped, at least a portion of the single elastic member may be disposed between the slide-guide member and the body in the radial direction, and at least a portion of the single elastic member may be disposed between the first member and the second member in the hammering-axis direction.
The first member may be configured to protrude radially outward from the slide-guide member, and
the second member may be disposed to be at least partly opposed to the first member in he hammering-axis direction.
Further, in an impact tool which is configured to linearly drive a tool accessory by causing a first hammering member to collide with the tool accessory, it is preferable to suppress transmission of vibration from the second hammering member or the first hammering member, like the above-described striker 51 and impact bolt 530, to the body. In view of this, the following features are provided.
An impact tool configured to linearly drive a tool accessory in a prescribed hammering-axis direction, the impact tool comprising:
a tool-accessory holding part configured to hold the tool accessory so as to be movable in the hammering-axis direction;
a body connected to the tool-accessory holding part;
a first hammering member disposed to be linearly movable in the hammering-axis direction and configured to drive the tool accessory in the hammering-axis direction by colliding with the tool accessory;
a circular cylindrical member disposed coaxially with a hammering axis within the body; and
a second hammering member disposed to be movable in the hammering-axis direction within the circular cylindrical member and configured to linearly move the first hammering member by colliding with the first hammering member, wherein:
the second hammering member has a circular column part having a circular column shape and has one or more elastic elements disposed on an outer circumferential surface of the circular column part, and
the one or more elastic elements are configured to be slidable in the hammering-axis direction along an inner circumferential surface of the circular cylindrical member and configured to hold the second hammering member within the circular cylindrical member in a state in which the outer circumferential surface is not in contact with the inner circumferential surface.
An impact tool configured to linearly drive a tool accessory in a prescribed hammering-axis direction, the impact tool comprising:
a tool-accessory holding part configured to hold the tool accessory so as to be movable in the hammering-axis direction;
a body connected to the tool-accessory holding part;
a first hammering member disposed be linearly movable in the hammering-axis direction and configured to drive the tool accessory in the hammering-axis direction by colliding with the tool accessory;
a circular cylindrical member disposed coaxially with a hammering axis within the body; and
a second hammering member disposed to be movable in the hammering-axis direction within the circular cylindrical member and configured to linearly move the first hammering member by colliding with the first hammering member, wherein:
the first hammering member has a circular column part having a circular column shape and has one or more elastic elements disposed on an outer circumferential surface of the circular column part, and
the one or more elastic elements are configured to be slidable in the hammering-axis direction along an inner circumferential surface of the tool-accessory holding part and to hold the first hammering member within the tool-accessory holding part in a state in which the outer circumferential surface is not in contact with the inner circumferential surface.
1: electric hammer, 2: motor, 21: output shaft, 3: first motion converting mechanism, 31: speed reducing mechanism, 33: first shaft, 34: eccentric pin, 36: first rod, 37: piston, 4: second motion converting mechanism, 43: second shaft, 46: second rod, 47: counterweight, 5: striking mechanism, 50: cylinder, 51: striker, 512; O-ring, 53, 530, 56; impact bolt, 531: upper end part, 532: lower end part, 533, 535: central part, 537: O-ring, 538; slide ring, 541: rubber ring, 542: washer, 543: washer, 55: air chamber, 6, 600, 605: tool holder, 60: body, 61: small-diameter part, 62: large-diameter part, 63: stepped part, 64: flange, 641: through hole, 642: through hole, 65: through hole, 651: tool insertion hole, 67: rubber ring, 68: washer, 7, 70, 700: inner sleeve, 701: cylindrical part, 702: fitted part 73, 703: protruding part, 704: connecting flange, 705: annular part, 706: screw fastening part, 707: first threaded hole, 75: O-ring, 8: connection part, 80, 83: connecting rubber, 800: through hole, 801: first member receiving part, 802: first recess, 803: first fitting hole, 806: second member receiving part, 807: second recess, 808: second fitting hole, 81: first member, 811: first compression part, 813: first connection part, 815: first threaded hole, 82: second member, 822: second compression part, 823: second connection part, 825: through hole, 830: through hole, 831: small-diameter part, 832: large-diameter part, 833: fitting recess, 834: protruding part, 835: through hole, 836: recess, 837: outer edge, 84: retainer ring, 841: through hole, 842: through hole, 843: stepped part, 849: O-ring, 86, 860: first screw, 87, 870: second screw, 9: tool accessory, 10: body, 11: body housing, 12, 120, 14: barrel, 121, 141: body, 122, 142: large-diameter part, 125, 144: second threaded hole, 143: screw fastening part, 146: inner lower end surface, 13: outer sleeve, 131: cylindrical part, 132: flange, 133: upper cylindrical part, 134: lower cylindrical part, 15: outer housing, 16: handle, 161: electric switch, 162: trigger, 19: power cable, 20: controller
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-099754 | May 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/017767 | 5/10/2017 | WO | 00 |
