Impact tools

Abstract

To stabilize an attitude of an impact tool during processing.SOLUTION: An impact tool has: a tool body that houses a motor and a driving mechanism and extends in a front-rear direction; a handle including a grip part that extends in a vertical direction orthogonal to the front-rear direction behind the tool body, has a lower end formed as a free end, and is arranged at a lower position relative to a driving axis; and a plurality of biasing members configured to elastically connect the tool body with the handle. The biasing members include: at least one first biasing member arranged at a higher position relative to the driving axis in the vertical direction; and at least one second biasing member arranged at a lower position relative to the driving axis in the vertical direction. In the impact tool, a biasing force of the at least one second biasing member is larger than a biasing force of the at least one first biasing member.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a percussion tool configured to linearly drive a tip tool.

Background Art

[0002] In a percussion tool that performs a machining operation on a workpiece by linearly driving a tip tool along a drive shaft, particularly large vibrations occur in the extending direction of the drive shaft. In contrast, various anti-vibration housing structures have been proposed. For example, in the percussion tool (hammer drill) disclosed in Patent Document 1, the handle is elastically connected to a tool body that houses a motor and a drive mechanism by a biasing member so as to be movable in the extending direction of the drive shaft. The user performs the machining operation by pushing the gripping portion (handle) against the workpiece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the structure disclosed in Patent Document 1, it is possible to effectively suppress the transmission of vibrations in the extending direction of the drive shaft from the tool body to the handle during the machining operation. On the other hand, in a percussion tool in which a gripping portion is provided below the drive shaft and the lower end of the gripping portion (handle) is a free end, the lower end portion of the handle tends to tilt closer to the workpiece during the machining operation. Therefore, there is room for improvement regarding the stabilization of the posture of the percussion tool during the machining operation. ​​​​​According to one aspect of the present disclosure, an impact tool is provided which is configured to drive a tip tool linearly. The impact tool comprises a motor, a drive mechanism, a tool body, a handle, and a plurality of biasing members. The drive mechanism is configured to drive the tip tool along a drive axis that defines the front-rear direction of the impact tool by the power of the motor. The tool body houses the motor and the drive mechanism and extends in the front-rear direction. The handle includes a gripping portion. The gripping portion extends in a vertical direction perpendicular to the front-rear direction, at the rear of the tool body. The lower end of the gripping portion is formed as a free end. The plurality of biasing members elastically connect the tool body and the handle and are configured to bias the tool body and the handle so that they move away from each other in the front-rear direction. The plurality of biasing members comprises at least one first biasing member positioned above the drive axis in the vertical direction, and at least one second biasing member positioned below the drive axis in the vertical direction. The biasing force provided by the at least one second biasing member is greater than the biasing force provided by the at least one first biasing member.

[0006] In an impact tool in which the tool body and handle are elastically connected, machining is performed by pressing the gripping portion against the workpiece. In an impact tool in which the gripping portion is offset downward with respect to the drive shaft and the lower end of the gripping portion (handle) is a free end, the gripping portion is relatively far from the drive shaft. Therefore, during machining, the handle (impact tool) tends to tilt so that the lower end of the handle approaches the workpiece. According to the impact tool of the above embodiment, the biasing force of at least one second biasing member is greater than the biasing force of at least one first biasing member, so the biasing force on the side closer to the gripping portion is greater than the biasing force on the side farther from the gripping portion. Therefore, tilting of the handle during machining can be suppressed. Consequently, the posture of the impact tool during machining can be stabilized. [Brief explanation of the drawing]

[0007] [Figure 1] This is an external view of a hammer drill. [Figure 2]This is a cross-section of a hammer drill. [Figure 3] This is a cross-sectional view of the hammer drill along line III-III in Figure 2. [Figure 4] Figure 3 is a cross-sectional view of the hammer drill along the line IV-IV. [Figure 5] Figure 3 is a cross-sectional view of the hammer drill along the VV line. [Figure 6] This diagram shows the spring holder and the second biasing spring. [Figure 7] This figure shows the state in which the second biasing spring is held in the spring holder. [Figure 8] This diagram shows the state in which the second biasing spring is held in the spring holder, and is a diagram for explaining the first locking part of the spring holder. [Figure 9] This diagram shows the left side of the motor housing assembled. [Figure 10] This is a magnified view of a portion of Figure 9. [Figure 11] This diagram shows the tool body with the handle assembled. [Figure 12] This diagram shows the state in which the second biasing spring is positioned between the tool body and the handle. [Figure 13] This is a diagram showing a portion of the hammer drill 1B of the second embodiment cut along a plane P2, illustrating the arrangement relationship between the first biasing member and the second biasing member. [Figure 14] This is a diagram showing a portion of the hammer drill 1C of the third embodiment cut along a plane P2, and is a partial cross-sectional view showing the arrangement relationship of the first biasing member and the second biasing member. [Modes for carrying out the invention]

[0008] In one non-limiting embodiment of the present disclosure, the at least one first biasing member and the at least one second biasing member may all be of the same specification. The number of the at least one second biasing member may be greater than the number of the at least one first biasing member. This configuration allows for greater biasing force on the side closer to the gripping portion than on the side further away from the gripping portion, using biasing members of the same specifications. Therefore, the cost of preventing the impact tool from tilting during machining can be reduced. Note that biasing members of the same specifications refer to biasing members of the same shape made from the same material.

[0009] In addition to or instead of the above embodiments, the number of at least one first biasing member may be 1, and the number of at least one second biasing member may be 2. This configuration allows the biasing force on the side closer to the gripping part to be greater than the biasing force on the side further away from the gripping part. Therefore, it is possible to suppress the tilting of the striking tool during machining.

[0010] In addition to or in lieu of the above embodiments, the two second biasing members may be provided symmetrically with respect to a virtual plane that includes the drive shaft and extends in the vertical direction. This configuration allows the biasing force acting between the tool body and the handle below the drive shaft to be equalized in the left-right direction. Therefore, machining operations can be performed stably.

[0011] In addition to or in lieu of the above embodiments, the spring constant of the at least one second biasing member may be greater than the spring constant of the at least one second biasing member. In this configuration, by utilizing the difference in spring constants, the biasing force on the side closer to the gripping part can be made greater than the biasing force on the side further away from the gripping part.

[0012] In addition to or in lieu of the above embodiments, the at least one second biasing member may be positioned between the tool body and the handle with a larger initial load than the at least one first biasing member. According to this embodiment, by utilizing the difference in the initial load, the biasing force on the side closer to the gripping portion can be made larger than the biasing force on the side farther from the gripping portion. Note that the "state where the initial load is applied" refers to a state in which a load is applied to the biasing spring in the compression direction in a static state and the biasing spring is compressed.

[0013] In addition to or instead of the above embodiment, the at least one second biasing member may be provided forward of the at least one first biasing member. According to this embodiment, compared with a configuration in which at least one first biasing member is provided on the front side of at least one second biasing member, the space behind the second biasing member (in front of the upper end of the gripping portion) can be effectively utilized. Therefore, the impact tool can be configured to be compact.

[0014] In addition to or instead of the above embodiment, the tool body may include a motor housing disposed at the rear portion of the tool body for housing the motor. The handle may include a cover portion that at least partially surrounds the motor housing. The upper end of the gripping portion may be connected to the cover portion. According to this embodiment, while covering the motor housing with the handle, it is possible to suppress the impact tool from tilting during the machining operation.

[0015] Hereinafter, referring to the drawings, representative and non-limiting embodiments of the present disclosure will be specifically described.

[0016] <First Embodiment> Referring to FIGS. 1 to 12, a hammer drill 1A according to a representative and non-limiting embodiment of the present disclosure will be described. The hammer drill 1A is an example of a power tool (so-called impact tool) that can linearly drive the tip tool 101 by striking the tip tool 101. More specifically, the hammer drill 1A is a power tool capable of performing an operation of linearly driving the tip tool 101 along a predetermined drive axis A1 (hereinafter referred to as an impact operation) and an operation of rotationally driving the tip tool 101 around the drive axis A1 (hereinafter referred to as a rotation operation).

[0017] As shown in Figure 1, the hammer drill 1A mainly comprises a tool body 2A, a handle 3A, and a plurality of biasing members that elastically connect the tool body 2A and the handle 3A. As shown in Figures 2 to 5, the hammer drill 1A of this embodiment includes three biasing springs (first biasing spring 51, second biasing springs 52L and 52R) as the plurality of biasing members.

[0018] The tool body 2A is a hollow body that houses the main mechanism of the hammer drill 1A. The tool body 2A is also referred to as the main housing, outer housing, or main body. As shown in Figure 2, the tool body 2A extends along the drive shaft A1 of the tip tool 101. A tool holder 79 is located within one end of the tool body 2A in the direction of extension of the drive shaft A1 (hereinafter simply referred to as the drive shaft direction). The tip tool 101 can be detachably attached to the tool holder 79. The tool body 2A mainly houses a motor 71 and a drive mechanism 75 configured to drive the tip tool 101 held in the tool holder 79 by the power of the motor 71. In this embodiment, the motor 71 is positioned such that the rotation axis A2 of the motor shaft 711, which rotates integrally with the rotor, extends parallel to the drive shaft A1. In this embodiment, a brushed motor is used as the motor 71.

[0019] The handle 3A is formed separately from the tool body 2A. The handle 3A is connected to the tool body 2A so as to be movable in the drive axis direction relative to the tool body 2A. The handle 3A has a gripping portion 39 that is grasped by the user. The gripping portion 39 extends so as to protrude from the tool body 2A in a direction intersecting the drive axis A1 (more specifically, in a direction approximately perpendicular to the drive axis A1 and the rotation axis A2). The protruding end 392 of the gripping portion 39 is a free end. The gripping portion 39 is equipped with a trigger 92 that is pressed (pulled) by the user. In the hammer drill 1A, the motor 71 is energized in response to the pressing operation of the trigger 92, and the drive mechanism 75 is driven, thereby performing a striking operation and / or rotational operation.

[0020] The following describes the detailed configuration of the hammer drill 1A. For convenience, in the following description, the direction in which the drive shaft A1 extends (the direction of the long axis of the tool body 2A) is defined as the front-rear direction of the hammer drill 1A. In the front-rear direction, the side on which the tool holder 79 is located is defined as the front side of the hammer drill 1A, and the opposite side is defined as the rear side. The direction perpendicular to the drive shaft A1 and roughly corresponding to the direction in which the gripping portion 39 extends (the direction perpendicular to the drive shaft A1 and the rotation shaft A2) is defined as the up-down direction of the hammer drill 1A. In the up-down direction, the base end 391 side of the gripping portion 39 is defined as the upper side of the hammer drill 1A, and the protruding end 392 side of the gripping portion 39 is defined as the lower side of the hammer drill 1A. Furthermore, the direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction of the hammer drill 1A. For the sake of explanation, in the following, a hypothetical plane that includes the drive shaft A1 and is perpendicular to the vertical direction will also be called plane P1, and a hypothetical plane that includes the drive shaft A1 and is parallel to the vertical direction will be called plane P2 (see Figure 3). In this embodiment, the handle 3A comprises two halves (left portion 30L and right portion 30R) connected to each other in the left-right direction. Plane P2 divides the handle 3A into the left portion 30L and the right portion 30R.

[0021] First, we will explain the configuration and internal structure of the tool body 2A.

[0022] The tool body 2A includes a gear housing 21, a motor housing 23, two holder receiving parts 63L and 63R, a plurality of guide parts 28, and a first spring holding part 27.

[0023] As shown in Figure 2, the gear housing 21 is a hollow body that houses the drive mechanism 75. The gear housing 21 constitutes the front half of the tool body 2A. The front end of the gear housing 21 is formed in a cylindrical shape, and the tool holder 79 is arranged inside it. The part of the gear housing 21 other than the front end is generally formed in a rectangular cylindrical shape. As this is a well-known configuration, a detailed explanation will be omitted, but the drive mechanism 75 includes a motion conversion mechanism 751 and a striking mechanism 752 that perform striking motion, and a rotation transmission mechanism 753 that performs rotational motion. In this embodiment, the motion conversion mechanism 751 employs a mechanism that converts rotational motion into linear motion using a rocking member (e.g., swash bearing, wobble plate / bearing) and a piston. However, instead of a rocking member, a motion conversion mechanism using, for example, a crankshaft may be employed. The rotation transmission mechanism 753 employs a reduction mechanism including a plurality of gears.

[0024] In this embodiment, the hammer drill 1A has three operating modes: a hammering-only mode in which only striking motion is performed, a rotation-only mode in which only rotational motion is performed, and a hammering-with-rotation mode in which both striking and rotational motions are performed simultaneously. As this is a well-known configuration, detailed illustrations and explanations are omitted, but the drive mechanism 75 operates according to the operating mode selected by the user via a mode switching knob.

[0025] As shown in Figure 2, the motor housing 23 is a hollow body that houses the motor 71. The motor housing 23 is a single, separate component (seamless component) formed independently of the gear housing 21. The motor housing 23 constitutes the rear half of the tool body 2A. The motor housing 23 is made of synthetic resin.

[0026] The motor housing 23 is formed in a generally cylindrical shape with an open front end and a closed rear end. The motor housing 23 has a front portion 24 and a rear portion 26. The front portion 24 has a shape (outer diameter and inner diameter) that is approximately the same as the rear end 22 of the gear housing 21. The outer diameter of the rear portion 26 is smaller than that of the front portion 24, and the rear end of the rear portion 26 is closed. A fan 72, fixed to the front end of the motor shaft 711, is located in the front portion 24. The majority of the motor 71 is located in the rear portion 26.

[0027] The multiple guide portions 28 will be described with reference to Figures 3, 5, and 10. The multiple guide portions 28 are configured to guide the sliding of the handle 3A relative to the tool body 2A. In this embodiment, each guide portion 28 is provided at multiple positions on the outer surface of the rear portion 26 with respect to the circumferential direction around the rotation axis A2.

[0028] As shown in Figure 3, each guide portion 28 includes a corner portion 261 and a guide plate 29. The corner portion 261 is a horn-shaped portion formed on the upper and lower left side of the plane P2 and on the upper and lower right side of the plane P2 of the rear portion 26. Each corner portion 261 extends in the front-rear direction.

[0029] The guide plate 29 is a component provided to cover the corner portion 261. Figure 10 shows the guide portion 28 (guide plate 29) provided on the upper right and lower right sides of the plane P2. The guide plate 29 is formed of, for example, a metal material. The two guide portions 28 on the left side of the plane P2 are provided symmetrically with respect to the plane P2, along with the two guide portions 28 on the right side of the plane P2. In this way, the motor housing 23 is provided with four guide portions 28.

[0030] As shown in Figures 5 and 10, the rear portion 26 is provided with a front wall 265 and a rear wall 266 perpendicular to the front-rear direction at the front and rear of each corner 261. The front wall 265 and the rear wall 266 each contact the guide receiving portion 34 (described later) of the handle 3A when the handle 3A slides in the front-rear direction, thereby defining the range of movement of the handle 3A in the front-rear direction.

[0031] In this embodiment, the gear housing 21 and the motor housing 23 are connected and fixed front to back. The connection portion between the gear housing 21 and the motor housing 23 will be described below.

[0032] Figure 5 shows a portion of the left side of the plane P2, consisting of the gear housing 21 and the motor housing 23. The configuration of the connecting portion between the gear housing 21 and the motor housing 23 is symmetrical with respect to the plane P2.

[0033] The rear end portion 22 of the gear housing 21 protrudes away from the plane P2 compared to the rest of the gear housing 21 (see Figures 5 and 10). The upper left, lower left, upper right, and lower right protruding portions (angular portions) 221, 222, 223, and 224 of the rear end portion 22 are hereinafter referred to as the first connecting portions 221 to 224. For example, Figure 5 shows the upper left and lower left first connecting portions 221 and 222, and Figure 10 shows the upper right and lower right first connecting portions 223 and 224. As illustrated by the first connecting portion 222 in Figure 5, the first connecting portions 221 to 224 are provided with holes 61 that penetrate the rear end portion 22 in the front-rear direction.

[0034] As shown in Figures 3, 5, and 10, the front portion 24 of the motor housing 23 includes upper left, lower left, upper right, and lower right corner portions 241, 242, 243, and 244 (hereinafter referred to as second connecting portions 241 to 244) corresponding to the rear end portion 22 of the gear housing 21. The second connecting portions 241, 242, 243, and 244 are located directly behind the first connecting portions 221, 222, 223, and 224, respectively. Regarding the arrangement of each connecting portion, the first connecting portions 221 and 223 of the gear housing 21 and the second connecting portions 241 and 243 of the motor housing 23 are located above the plane P1. On the other hand, the first connecting portions 222 and 224 of the gear housing 21 and the second connecting portions 242 and 244 of the motor housing 23 are located below the plane P1.

[0035] As shown in Figures 5 and 10, the rear ends of the second connecting portions 242 and 244 located in the lower left and lower right are cut out toward the plane P2. Holder receiving portions 63L and 63R are formed in these cutouts. Furthermore, the rear ends 22 of the second connecting portions 241 and 243 located in the upper left and upper right have recesses into which the front end of the bellows member 91, which will be described later, can be fitted.

[0036] As illustrated in Figure 5 with the second connecting portion 242, the second connecting portions 241 to 244 are provided with holes 62 that have an opening at least on the front side and extend in the front-rear direction. The holes 62 are screw holes. Each hole 62 of the second connecting portions 241 to 244 communicates with each hole 61 of the first connecting portions 221 to 224 in the front-rear direction. Screws 95 are inserted through each hole 61 from the front side (gear housing 21 side) and screwed into the hole 62. In this way, the gear housing 21 and the motor housing 23 are connected and fixed in the front-rear direction.

[0037] As shown in Figure 5, at least the holes 62 provided in the second connecting portions 242 and 244 penetrate in the front-to-back direction. Also, in the second connecting portions 242 and 244, the rear end 952 of the screw 95 is located in front of the rear end (opening 622) of the hole 62. The first locking portion 41 of the spring holders 4L and 4R, which will be described later, is inserted into the region of the hole 62 provided in the second connecting portions 242 and 244 from the opening 622 to the rear end 952 of the screw 95. This region functions as a second locking portion 621 for locking the spring holders 4L and 4R.

[0038] As shown in Figure 3, the holder receiving portions 63L and 63R are located below the plane P1 of the front portion 24. The holder receiving portions 63L and 63R are arranged symmetrically on the plane P2 and spaced apart in the left-right direction. In this embodiment, the holder receiving portions 63L and 63R are each formed by the notched portions of the second connecting portions 242 and 244 and the second locking portions 621 and 621, respectively. Figure 10 shows the right holder receiving portion 63R, and Figure 11 shows the left holder receiving portion 63L. The holder receiving portions 63L and 63R each include a first surface 631 perpendicular to the front-rear direction and a second surface 632 provided around the first surface 631 behind it. The rear opening 622 described above is provided on the first surface 631. The holder receiving portions 63L and 63R can hold the second biasing springs 52L and 52R via the spring holders 4L and 4R described later.

[0039] Next, we will describe the configuration and internal structure of handle 3A.

[0040] The handle 3A is formed by connecting and fixing the left portion (left shell, left handle portion) 30L and the right portion (right shell, right handle portion) 30R to each other in the left-right direction by screws at multiple points. As shown in Figures 1 and 2, the handle 3A includes a cover portion 31 and a gripping portion 39.

[0041] The cover portion 31 constitutes the upper part of the handle 3A. The cover portion 31 is positioned to partially surround the motor housing 23. In this embodiment, the cover portion 31 covers the portion of the rear portion 26 excluding the front end and extends further back than the rear portion 26.

[0042] As shown in Figure 3, the cover portion 31 is provided with a plurality of guide receiving portions 34. The guide receiving portions 34 are provided on the upper and lower parts on the left side of the plane P2 and on the upper and lower parts on the right side of the plane P2 on the inner surface of the cover portion 31. Each guide receiving portion 34 is positioned opposite to each guide portion 28 provided on the rear portion 26 and is configured to engage with the guide portion 28 (guide plate 29). In this embodiment, each guide receiving portion 34 is formed on the inner surface of the cover portion 31 so as to be angularly recessed away from the plane P2 and extend in the front-rear direction. The guide portion 28 and the guide receiving portion 34 slide against each other in response to vibrations generated during machining, thereby guiding the relative movement of the handle 3A and the tool body 2A in the front-rear direction.

[0043] The cover portion 31 further comprises a first spring retaining portion 33 and second spring retaining portions 35, 35. These will be described in detail later.

[0044] An opening 311 is provided in the upper part of the cover portion 31. Part of the opening 311 is positioned on the plane P2. The opening 311 is formed by cutting the upper wall of the left portion 30L and the upper wall of the right portion 30R in a direction away from the plane P2. A lever 96 protrudes upward from the opening 311. The lever 96 is connected to the brush unit of the motor 71 and is configured to switch the rotation direction of the motor 71.

[0045] Furthermore, a bellows member 91 is positioned between the front portion 24 of the motor housing 23 and the cover portion 31 of the handle 3A. This bellows member 91 is an annular member positioned to surround the front end of the rear portion 26. The bellows member 91 is formed to be expandable and contractible in the front-rear direction. This prevents dust from entering the gap between the motor housing 23 and the handle 3A.

[0046] The gripping portion 39 is the part that is gripped by the user. The gripping portion 39 extends downward from the cover portion 31, along the vertical direction. In detail, the upper end 391 of the gripping portion 39 is connected to the rear end of the cover portion 31, and the lower end (protruding end 392) of the gripping portion 39 is configured as a free end. In other words, the gripping portion 39 is supported by the cover portion 31 in a cantilevered manner. It can also be said that the gripping portion 39 is positioned offset downward with respect to the drive shaft A1 (plane P1). In this embodiment, the gripping portion 39 is positioned below the motor 71.

[0047] As shown in Figure 2, a trigger 92 is located at the upper end of the gripping section 39. Inside the gripping section 39, a switch 93 is located behind the trigger 92. The switch 93 is normally held in the off position and is turned on in response to the pressing operation of the trigger 92. When the switch 93 is turned on, the motor 71 is energized. A power cord 94, which can be connected to an external AC power source, extends from the lower end 392 of the gripping section 39 (the free end, protruding end of the handle 3A). Regarding the arrangement of the gripping section 39 in the hammer drill 1A, it can be said that the gripping section 39 is located below the drive shaft A1, or below the plane P2. Furthermore, it can be said that the gripping section 39 is located below the rotation shaft A2. Also, it can be said that the gripping section 39 is located below the motor 71.

[0048] The following describes the details of the connection structure between the tool body 2A and the handle 3A. The tool body 2A and the handle 3A are biased to move away from each other in the front-rear direction by a plurality of biasing members (first biasing spring 51, second biasing springs 52L, 52R). In this embodiment, the hammer drill 1A is configured such that the biasing force below the drive shaft A1 (below the plane P1, closer to the gripping portion 39) is greater than the biasing force above the drive shaft A1 (above the plane P1, further away from the gripping portion 39).

[0049] As shown in Figures 2 to 4, the first biasing spring 51 elastically connects the tool body 2A and the handle 3A above the drive shaft A1 (above the plane P1). In this embodiment, the first biasing spring 51 is positioned on the plane P2. As shown in Figures 3 to 5, the second biasing springs 52L and 52R elastically connect the tool body 2A and the handle 3A below the drive shaft A1 (above the plane P1). The second biasing springs 52L and 52R are positioned on the left and right sides, respectively, with respect to the plane P2. The second biasing springs 52L and 52R are symmetrical with respect to the plane P2. In this embodiment, the first biasing spring 51 and the second biasing springs 52L and 52R are all of the same specifications. Springs of the same specifications refer to springs of the same shape made from the same material. Therefore, the spring constants of the first biasing spring 51, the second biasing spring 52L, and the second biasing spring 52R are all equal. In this embodiment, compression coil springs are used as the first biasing spring 51, the second biasing springs 52L, and 52R.

[0050] As shown in Figures 3 and 4, the first biasing spring 51 is positioned between the first spring retaining portion 27 provided on the tool body 2A and the first spring retaining portion 33 provided on the handle 3A.

[0051] In this embodiment, the first spring retaining portion 27 is fixed to the outer surface (upper wall 263, see Figure 3) of the rear portion 26 of the motor housing 23. The first spring retaining portion 27 has a contact surface 271 perpendicular to the front-rear direction and a retaining wall 272 provided around the contact surface 271. The retaining wall 272 opens to the right. The first spring retaining portion 27 (contact surface 271) is positioned on a plane P2. The contact surface 271 receives (contacts) the front end 511 of the first biasing spring 51.

[0052] The first spring retaining portion 33 is fixed to the inner surface of the left portion 30L of the cover portion 31. The first spring retaining portion 33 has a contact surface 331 perpendicular to the front-rear direction and a retaining wall 332 that has an opening on the right side and is provided around the contact surface 331. A part of the first spring retaining portion 33 (contact surface 331) is positioned on a plane P2 and is located behind (directly behind) the contact surface 271 of the first spring retaining portion 27 of the motor housing 23. The contact surface 331 receives (contacts) the rear end 512 of the first biasing spring 51.

[0053] The second biasing springs 52L and 52R are positioned between the spring holders 4L and 4R, which are attached to the holder receiving portions 63L and 63R of the tool body 2A, and the second spring holding portions 35 and 35 provided on the handle 3A. The spring holders 4L and 4R (left spring holder and right spring holder) are configured to hold the front ends 521 and 521 of the second biasing springs 52L and 52R (left spring and right spring). The second spring holding portions 35 and 35 are configured to hold the rear ends 522 and 522 of the second biasing springs 52L and 52R.

[0054] The second biasing spring 52L and the elements that hold the second biasing spring 52L (holder receiving portion 63L, spring holder 4L, second spring holding portion 35) are arranged symmetrically in the plane P2 with the second biasing spring 52R and the elements that hold the second biasing spring 52R (holder receiving portion 63R, spring holder 4R, second spring holding portion 35).

[0055] The second spring retaining parts 35, 35 are each located at the front end of the cover part 31 and are fixed to the inner walls of the left part 30L and the right part 30R, respectively. The second spring retaining parts 35, 35 are provided corresponding to the holder receiving parts 63L and 63R of the motor housing 23, respectively. As described above, the left element that holds the second biasing spring 52L and the second biasing spring 52L and the right element that holds the second biasing spring 52R and the second biasing spring 52R have similar configurations. Therefore, in the following description, the left second biasing spring 52L, holder receiving part 63L, spring holder 4L, and second spring retaining part 35 will be mainly used as examples.

[0056] Figure 4 shows the second spring retaining portion 35 provided in the left portion 30L. The second spring retaining portion 35 has a contact surface 351 perpendicular to the front-rear direction and a retaining wall 352 provided around the contact surface 351. The contact surface 351 of the second spring retaining portion 35 receives (contacts) the rear end 522 of the second biasing spring 52L. As shown in Figure 4, the contact surface 351 that receives the rear end 522 of the second biasing spring 52L is positioned in front of the contact surface 331 that receives the rear end 512 of the first biasing spring 51, and the second biasing springs 52L and 52R are positioned in front of the first biasing spring 51.

[0057] The spring holders 4L and 4R are configured to be connectable to the tool body 2A via the holder receiving portions 63L and 63R of the tool body 2A. As shown in Figure 3, the spring holders 4L and 4R are configured to lock (fit) into the rear end portion of the front portion 24 (the notched portion of the second connecting portion 242 and 244). Figures 7 and 8 illustrate the spring holder 4L and the second biasing spring 52L. The spring holder 4L comprises an outer wall 42, a support portion 43 and a rear wall 44 fixed to the inside of the outer wall 42, a first locking portion 41, a protruding portion 46, and an engaging portion 45.

[0058] The outer wall 42 is formed in a roughly L-shape (angular) cross-section. The outer wall 42 has an outer surface 42s that is visible on the outside of the hammer drill 1A when the spring holder 4L is attached to the holder receiving portion 63L (hereinafter referred to as the attached state). As shown in Figure 1, in the attached state, the outer surface 42s of the spring holder 4L is continuous with the outer surface 24s of the motor housing 23 (front portion 24).

[0059] As shown in Figure 8, the support portion 43 is a block-shaped portion fixed to the corner portion of the inner surface of the outer wall 42. In the mounted state, the support portion 43 has a first surface 431 that is perpendicular to the front-rear direction and defines the front end of the support portion 43. The first surface 431 is configured to abut against the first surface 631 of the holder receiving portion 63L (see Figure 11). The rear wall 44 is connected to the rear end of the support portion 43 and is formed to be perpendicular to the front-rear direction. The rear wall 44 has a front surface 441 located on the front side and a rear surface 442 located on the rear side in the mounted state. As shown in Figure 4, the front surface 441 is configured to abut against the second surface 632 of the holder receiving portion 63L in the mounted state.

[0060] The first locking portion 41 is a convex (cylindrical) portion that protrudes forward from the first surface 431. As shown in Figure 5, the first locking portion 41 can be inserted into the hole 62 (second locking portion 621) through the opening 622 of the holder receiving portion 63L. In the installed state, the first locking portion 41 is inserted into the second locking portion 621, and the first surface 431 and front surface 441 of the spring holder 4L come into contact with the first surface 631 and the second surface 632 of the holder receiving portion 63L, respectively.

[0061] The protruding portion 46 is the part that protrudes rearward from the rear surface 442. As shown by the white arrow in Figure 6, the front end of the second biasing spring 52L can be inserted (more specifically, lightly press-fitted) into the protruding portion 46. With the second biasing spring 52L inserted into the protruding portion 46 and the spring holder 4L attached to the holder receiving portion 63L, the front end 521 of the second biasing spring 52L abuts against the rear surface 442, and the rear end 522 of the second biasing spring 52L abuts against the contact surface 351 (see Figures 4 and 5).

[0062] The engaging portion 45 is configured to engage with a removal tool for removing the spring holder 4L from the tool body 2A. In this embodiment, the engaging portion 45 is a recessed portion of the outer surface 42s of the spring holder 4L and is visible on the outside of the spring holder 4L when installed. The engaging portion 45 is formed in a substantially L-shape to conform to the shape of the outer wall 42. The removal tool can be any tool whose tip can engage with the engaging portion 45, such as a flat-tip screwdriver. The user can remove the spring holder 4L from the holder receiving portion 63L by engaging the removal tool with the engaging portion 45 and moving the spring holder 4L backward so that the spring holder 4L (first locking portion 41) is separated from the holder receiving portion 63L (second locking portion 621). Therefore, in the hammer drill 1A of this embodiment, maintenance such as replacing the second biasing springs 52L and 52R can be easily performed.

[0063] As described above, the connecting structure allows the first biasing spring 51 to be interposed in a compressed state between the contact surface 271 of the first spring holding portion 27 in the motor housing 23 and the contact surface 331 of the first spring holding portion 33 in the cover portion 31, as shown in Figure 4. This causes the first biasing spring 51 to bias the tool body 2A and the handle 3A so that they move away from each other in the front-rear direction on the upper side of the drive shaft A1 (the upper side of the plane P1, i.e., the side farther from the gripping portion 39).

[0064] Furthermore, as shown in Figure 5, the second biasing spring 52L is interposed in a compressed state between the rear surface 442 of the spring holder 4L attached to the holder receiving portion 63L in the motor housing 23 and the contact surface 351 of the second spring holding portion 35 in the cover portion 31 (left side portion 30L). As a result, the second biasing spring 52L biases the tool body 2A and the handle 3A so that they move away from each other in the front-rear direction on the lower side of the drive shaft A1 (the lower side of the plane P1, i.e., the side closer to the gripping portion 39) and on the left side of the plane P2. Similarly, the second biasing spring 52R is interposed in a compressed state between the rear surface 442 of the spring holder 4R attached to the holder receiving portion 63R in the motor housing 23 and the contact surface 351 of the second spring holding portion 35 in the cover portion 31 (right side portion 30R). As a result, the second biasing spring 52R biases the tool body 2A and the handle 3A so that they move away from each other in the front-rear direction on the lower side of the drive shaft A1 (the lower side of the plane P1, i.e., the side closer to the gripping portion 39) and on the right side of the plane P2. Thus, in the hammer drill 1A, the front ends 521, 521 of the second biasing springs 52L, 52R are held by the tool body 2A via spring holders 4L, 4R, while the rear ends 522, 522 of the second biasing springs 52L, 52R are directly held by the left portion 30L and the right portion 30R of the handle 3A.

[0065] In this embodiment, the first biasing spring 51, the second biasing springs 52L and 52R are each positioned between the tool body 2A and the handle 3A with equal initial loads applied to them.

[0066] The hammer drill 1A described above can be manufactured, for example, as follows:

[0067] (i) Prepare tool body 2A.

[0068] (ii) Assemble one of the left portion 30L and the right portion 30R onto the tool body 2A. Specifically, position the left portion 30L and the right portion 30R such that the portion corresponding to the cover portion 31 of the handle 3A covers a part of the motor housing 23. In this embodiment, as shown in Figures 9 and 10, the left portion 30L is positioned such that the portion of the left portion 30L corresponding to the cover portion 31 covers the left outer side of the rear portion 26. In this embodiment, the left portion 30L is further positioned such that the lever 96 is located in the portion of the left portion 30L corresponding to the opening 311. At this time, the tool body 2A and the left portion 30L are placed on a desk or the like so that the outer surface of the left portion 30L is in contact with the desk or the like (that is, with the inner surface of the left portion 30L facing vertically upward), and the components of the handle 3A (for example, the switch 93, trigger 92, wiring, etc.) are assembled to the left portion 30L. In addition, the first biasing spring 51 is positioned between the first spring holding portion 33 of the left portion 30L and the first spring holding portion 27 of the motor housing 23. More specifically, the front end 511 and rear end 512 of the first biasing spring 51 are brought into contact with the contact surface 331 of the first spring retaining portion 33 and the contact surface 271 of the first spring retaining portion 27, respectively.

[0069] (iii) Next, the other of the left portion 30L and the right portion 30R is assembled to the intermediate product manufactured in (ii). In this embodiment, the inner surface of the right portion 30R is oriented vertically downward, and the right portion 30R and the left portion 30L are brought into contact in the left-right direction and connected to each other in the left-right direction by screws. When (i) to (iii) are completed, as shown in Figure 11, the portion of the rear portion 26 of the motor housing 23, excluding the front end, is sandwiched between the left portion 30L and the right portion 30R.

[0070] (iv) A second biasing spring 52L is placed between the tool body 2A and the left side portion 30L. For example, as shown in Figures 7 and 8, the front end of the second biasing spring 52L is inserted into the protrusion 46 of the spring holder 4L. More specifically, the front end of the second biasing spring 52L is lightly press-fitted into the protrusion 46 so that the front end 521 of the second biasing spring 52L abuts against the rear surface 442 of the spring holder 4L. This holds the second biasing spring 52L in the spring holder 4L. Next, the rear end 522 of the second biasing spring 52L, held in the spring holder 4L, is brought into contact with the contact surface 351 of the second spring holding portion 35 of the left portion 30L. At this time, the spring holder 4L is positioned in the holder receiving portion 63L while the second biasing spring 52L is pressed against the contact surface 351 and compressed. More specifically, the second biasing spring 52L is compressed to position the first locking portion 41 of the spring holder 4L directly behind the second locking portion 621 of the holder receiving portion 63L. In this state, when the compression is released, the first locking portion 41 locks into the second locking portion 621, and the spring holder 4L is positioned in the holder receiving portion 63L (see Figures 5 and 12).

[0071] (v) A second biasing spring 52R is placed between the tool body 2A and the right-side portion 30R. Similar to (iv) above, the front end of the second biasing spring 52R is inserted into the protruding portion 46 of the spring holder 4R. Next, the rear end 522 of the second biasing spring 52R held by the spring holder 4R is brought into contact with the contact surface 351 of the second spring holding portion 35 of the right portion 30R. At this time, the spring holder 4R is positioned on the holder receiving portion 63R while the second biasing spring 52R is pressed against the contact surface 351 and compressed. More specifically, the second biasing spring 52R is compressed so that the first locking portion 41 of the spring holder 4R is positioned directly behind the second locking portion 621 of the holder receiving portion 63R. In this state, when the compression is released, the first locking portion 41 locks with the second locking portion 621 and the spring holder 4R is positioned on the holder receiving portion 63R. Note that the order of (iv) and (v) above may be reversed.

[0072] As described above, the tool body 2A and the handle 3A are elastically connected by the first biasing spring 51 on the upper side of the drive shaft A1 (upper side of the plane P1), and the tool body 2A and the left portion 30L and the right portion 30R are elastically connected by the second biasing springs 52L and 52R, respectively, on the lower side of the drive shaft A1 (lower side of the plane P1), thereby manufacturing the hammer drill 1A.

[0073] The bellows member 91 may be attached to the tool body 2A in (i) above so as to surround the front end of the rear portion 26. In this embodiment, the bellows member 91 is made of rubber and is configured to be expandable and contractible in the radial direction. Therefore, by extending the bellows member 91 in the radial direction, a gap can be secured to perform (iv) and (v) above.

[0074] In a hammer drill 1A in which the handle 3A is configured to be separable into a left portion 30L and a right portion 30R, and biasing springs are positioned (interposed) between the tool body 2A and the left portion 30L, and between the tool body 2A and the right portion 30R, the process of positioning the biasing springs may take a considerable amount of time for the manufacturer. This is because when the left portion 30L and the right portion 30R are connected in the left-right direction, the inner surface of one of the left portion 30L and the right portion 30R is directed vertically downward. In this embodiment, because the inner surface of the right portion 30R is directed vertically downward, depending on the manufacturer's skill level, the second biasing spring 52R temporarily held in the right portion 30R (second spring holding portion 35) may fall or shift from the second spring holding portion 35. Furthermore, the reason the inner surface of the right portion 30R is oriented vertically downward is that, as described above, the components of the handle 3A (switch 93, trigger 92, etc.) are placed in the left portion 30L, which is located behind the tool body 2A. Therefore, the inner surface of the left portion 30L is oriented vertically upward so that the intermediate part of the hammer drill 1A can be placed on a desk or the like.

[0075] Furthermore, from the viewpoint of durability and other factors, it is preferable that the biasing members used in the hammer drill 1A (first biasing spring 51, second biasing springs 52L, 52R) do not appear on the outer surface of the hammer drill 1A. Therefore, generally, the spring holding parts are arranged on the inside of the hammer drill (inside the tool body 2A and inside the handle 3A). Consequently, it may take a relatively long time to connect and fix the left portion 30L and the right portion 30R in the left-right direction so as to cover the rear of the tool body 2A, and then to position the biasing springs between the tool body 2A and the handle 3A.

[0076] In contrast, in this embodiment, as described in (i) to (v) above, the second biasing springs 52L and 52R can be easily positioned between the tool body 2A and the left portion 30L of the handle 3A, and between the tool body 2A and the right portion 30R of the handle 3A, respectively, using the spring holders 4L and 4R. Therefore, the hammer drill 1A can be easily manufactured.

[0077] Furthermore, the outer surfaces 42s, 42s of the spring holders 4L, 4R are continuous with the outer surface 24s of the tool body 2A when installed, thus improving the aesthetic design of the hammer drill 1A. In addition, alignment between the spring holders 4L, 4R and the holder receiving parts 63L, 63R is easy.

[0078] Furthermore, the spring holders 4L and 4R (first locking part 41) can be locked to the motor housing 23 by utilizing the rear part (second locking part 621) of the hole 62 into which the screw 95 for connecting the gear housing 21 and the motor housing 23 is inserted. This simplifies the structure for locking the spring holders 4L and 4R to the tool body 2A.

[0079] Furthermore, the hammer drill 1A of this embodiment has the following advantages.

[0080] In a hammer drill 1A in which the tool body 2A and the handle 3A are elastically connected, machining is performed by pressing the gripping portion 39 against the workpiece. In a hammer drill 1A in which the gripping portion 39 is offset downward with respect to the drive shaft A1 and the lower end 392 of the gripping portion 39 (handle 3A) is a free end, the handle 3A (hammer drill 1A) tends to tilt when the user presses the gripping portion 39 against the workpiece during machining, causing the lower end 392 of the handle 3A to move closer to the workpiece. In the hammer drill 1A of this embodiment, two biasing members (second biasing springs 52L, 52R) are positioned closer to the gripping portion 39, and one biasing member (first biasing spring 51) is positioned further away from the gripping portion 39. Therefore, the biasing force on the side closer to the gripping portion 39 is greater than the biasing force on the side further away from the gripping portion 39. Therefore, during machining, the hammer drill 1A can be prevented from tilting so that the lower end 392 of the handle 3A approaches the workpiece. This stabilizes the position of the hammer drill 1A during machining. In other words, the user can perform machining operations stably.

[0081] Furthermore, since the first biasing spring 51 and the second biasing springs 52L and 52R are of the same specifications, costs associated with stabilizing the machining process can be reduced. In addition, compared to configurations where springs of different specifications are used for the first biasing spring 51 and the second biasing springs 52L and 52R, errors during assembly can be prevented.

[0082] Furthermore, the second biasing springs 52L and 52R are positioned in front of the first biasing spring 51. Therefore, compared to a configuration in which the second biasing springs 52L and 52R are positioned behind the first biasing spring 51, the gripping portion 39 and the second biasing springs 52L and 52R are spaced apart in the front-to-back direction, allowing the trigger 92 to be positioned closer to the drive shaft A1 on the gripping portion 39 (near the upper end 391 of the gripping portion 39). This enables stabilization of the machining operation and a more compact hammer drill 1A.

[0083] Furthermore, in the hammer drill 1A, the first biasing spring 51 is positioned approximately in the center (on the plane P2) in the left-right direction, while the second biasing springs 52L and 52R are positioned symmetrically with respect to the plane P2. Therefore, the biasing force acting between the tool body 2A and the handle 3A can be equalized in the left-right direction. Consequently, machining operations can be performed stably.

[0084] Furthermore, since the rear portion 26 of the motor housing 23 is covered by the cover portion 31, tilting of the handle 3A (hammer drill 1A) during machining can be further suppressed. During machining, vibrations mainly occur in the drive axis direction (forward and backward direction) of the hammer drill 1A due to the force with which the drive mechanism 75 drives the tip tool 101 and the reaction force from the workpiece to the impact force of the tip tool 101. In this embodiment, the guide receiving portion 34 of the handle 3A and the guide portion 28 of the motor housing 23 allow the handle 3A to slide smoothly in the forward and backward direction relative to the tool body 2A.

[0085] The following describes another configuration in which the biasing force on the side closer to the gripping portion 39 is greater than the biasing force on the side further away from the gripping portion 39. In the following, the same reference numerals are used for components similar to those in the above-described embodiment, and their descriptions are omitted.

[0086] <Second Embodiment> Figure 13 shows a hammer drill 1B of the second embodiment. In the hammer drill 1B, one first biasing spring 51 is positioned above the drive shaft A1, and one second biasing spring 52B is positioned below the drive shaft A1. In this embodiment, the first biasing spring 51 and the second biasing spring 52B are springs of different specifications. The spring constant of the second biasing spring 52B is greater than the spring constant of the first biasing spring 51.

[0087] The hammer drill 1B of this embodiment includes a second spring retaining portion 36B that holds the front end 521 of the second biasing spring 52B and a second spring retaining portion 35B that holds the rear end 522 of the second biasing spring 52B, both located on a plane P2. The second spring retaining portion 36B is located at the lower part of the motor housing 23. The second spring retaining portion 35B is located behind the second spring retaining portion 36B and on the inner surface of the cover portion 31. As in the first embodiment, the initial loads of the first biasing spring 51 and the second biasing spring 52B are equal.

[0088] In the second embodiment, since the second biasing spring 52B has a larger spring constant than the first biasing spring 51, it is possible to make the biasing force on the side closer to the gripping part 39 greater than the biasing force on the side further away from the gripping part 39, while employing a configuration in which the same number of springs are placed on the upper side and the lower side of the drive shaft A1, respectively. Therefore, it is possible to suppress the hammer drill 1B from tilting during machining. In addition, in the second embodiment, since there is only one second biasing spring 52B, there is the advantage that it is not necessary to provide space for placing multiple second biasing springs on the side closer to the gripping part 39.

[0089] <Third Embodiment> Figure 14 shows a hammer drill 1C of the third embodiment. In the hammer drill 1C, one first biasing spring 51 is positioned above the drive shaft A1, and one second biasing spring 52C is positioned below the drive shaft A1. Similar to the first embodiment, the first biasing spring 51 and the second biasing spring 52B are springs of the same specifications.

[0090] The distance L1 shown in Figure 14 is the distance between the first spring retaining part 27 (contact surface 271) that receives the front end 511 of the first biasing spring 51 and the first spring retaining part 33 (contact surface 331) that receives the rear end 512 of the first biasing spring 51. The distance L2 is the distance between the second spring retaining part 36B (contact surface 361) that receives the front end 521 of the second biasing spring 52C and the second spring retaining part 35C (contact surface 351) that receives the rear end 522 of the second biasing spring 52C. In this embodiment, the second spring retaining part 35C is located further forward than the second spring retaining parts 35 and 35B in the above-described embodiment. Therefore, the distance L2 is smaller than the distance L1. In other words, the second biasing spring 52C is assembled to the hammer drill 1C with a larger initial load than the first biasing spring 51.

[0091] According to the third embodiment, since the initial load of the second biasing spring 52C is greater than the initial load of the first biasing spring 51, the biasing force on the side closer to the gripping part 39 can be made greater than the biasing force on the side further away from the gripping part 39, while employing a configuration in which the same number of springs of the same specifications are placed on the upper and lower sides of the drive shaft A1, respectively. Therefore, tilting of the hammer drill 1C during machining can be suppressed. In addition, the third embodiment has the advantage that, similar to the second embodiment, it is not necessary to provide space for placing multiple second biasing springs on the side closer to the gripping part 39. Furthermore, similar to the first embodiment, since springs of the same specifications are used, costs associated with stabilizing the machining work can be suppressed. Also, compared to a configuration in which springs of different specifications are used as the first biasing spring 51 and the second biasing spring 52C, errors during assembly can be prevented.

[0092] The correspondence between the configuration (features) of the above embodiment and the configuration (features) of the present disclosure is shown below. However, the configuration (features) of the embodiment is merely an example and does not limit the configuration (features) of the present disclosure or the present invention.

[0093] Hammer drills 1A, 1B, and 1C are examples of "impact tools". The first biasing spring 51 is an example of a "first biasing member". The second biasing springs 52L, 52R, 52B, and 52C are examples of "second biasing members".

[0094] <Other Embodiments> The striking tools relating to this disclosure are not limited to the hammer drills 1A, 1B, and 1C of the embodiments described above. For example, non-limiting modifications such as those exemplified below can be made. At least one of these modifications may be adopted in combination with the hammer drills 1A, 1B, and 1C and at least one of the configurations (features) described in the claims.

[0095] The number of biasing springs is not limited to the above embodiment. For example, the number of first biasing springs above the drive shaft A1 may be two or more, and the number of second biasing springs below the drive shaft A1 may be three or more. Also, for example, two first biasing springs 51, 51 may be arranged on the left side and the right side of the plane P2, respectively, similar to the second biasing springs 52L, 52R in the above embodiment. In this case, the front ends 511, 511 of the first biasing springs 51, 51 are connected to the tool body 2A via spring holders 4L, 4R, and the rear ends 522, 522 may be directly connected to the left portion 30L and the right portion 30R. With this configuration as well, a hammer drill can be easily manufactured, similar to the above embodiment.

[0096] The spring holders 4L and 4R may be connected to the handle 3A instead of the tool body 2A. For example, the second biasing spring 52L may be connected to the left portion 30L via the spring holder 4L and directly connected (held) to the tool body 2A. Similarly, the second biasing spring 52R may be connected to the right portion 30R via the spring holder 4R and directly connected (held) to the tool body 2A. Alternatively, the second biasing spring 52L may be connected to the left portion 30L via the spring holder 4L and directly connected to the tool body 2A, while the second biasing spring 52R may be connected to the tool body 2A via the spring holder 4R and directly connected to the right portion 30R. With this configuration as well, the hammer drill can be easily manufactured, similar to the above embodiment.

[0097] Furthermore, from the viewpoint of preventing the hammer drills 1A, 1B, and 1C from tilting so that the handle 3A approaches the workpiece during machining, it is preferable that the (1) number, (2) initial load, and (3) spring constant of at least one first biasing spring and at least one second biasing spring be adjusted so that the biasing force of the first biasing spring above the drive shaft A1 is smaller than the biasing force of the second biasing spring below the drive shaft A1. If adjusting any one of (1) to (3) does not result in the biasing force of the first biasing spring above the drive shaft A1 and the biasing force of the second biasing spring below the drive shaft A1 reaching the target set value, it is also possible to combine two or all three of (1) to (3).

[0098] The biasing members that bias the tool body 2A and the handle 3A away from each other in the front-rear direction are not limited to the first biasing spring 51, the second biasing springs 52L, 52R, 52B, and 52C. For example, a spring of a different type than a compression coil spring (e.g., a tension coil spring, a leaf spring, a torsion spring, etc.) can be used. Alternatively, an elastic member other than a spring, such as rubber or synthetic resin, may be used as the biasing member. The configuration of the spring holders 4L and 4R, the holder receiving parts 63L and 63R, the first spring holding parts 27 and 33, and the second spring holding parts 35, 35B, 35C, and 36B can be appropriately changed depending on the type and position of the biasing member used.

[0099] In the above embodiments, hammer drills 1A, 1B, and 1C are exemplified as impact tools, but the features of this disclosure may also be applied to other power tools capable of performing impact operations (for example, an electric hammer capable of performing only impact operations and not rotational operations). Furthermore, the hammer drill 1A may have only two operating modes: an impact mode and a rotation mode. Depending on the impact tool to which the features of this disclosure are applied, the configuration and arrangement of the motor 71 and the drive mechanism 75 may be appropriately changed. For example, a DC motor (for example, a brushless DC motor) may be used for the motor 71. In this case, for example, the tool body 2A or the handle 3A may be provided with a battery mounting section to which a rechargeable battery (also called a battery pack) can be attached and detached.

[0100] Furthermore, in view of the spirit of this disclosure and the embodiments described above, the following embodiments can be constructed. At least one of the following embodiments may be adopted in combination with the embodiments and their modifications described above, and at least one of the configurations (features) described in each claim. [Aspect 1] The rotating shaft of the motor extends below the drive shaft and parallel to the drive shaft, The gripping portion is positioned below the rotation axis. [Aspect 2] The rotating shaft of the motor extends below the drive shaft and parallel to the drive shaft, The gripping portion is positioned below the motor. [Aspect 3] The cover portion at least partially surrounds the motor housing in the circumferential direction around the rotation axis. [Aspect 4] The motor housing comprises a plurality of guide portions configured to guide the handle so that the handle moves relative to the tool body along the drive shaft, The cover portion includes a plurality of guide receiving portions positioned corresponding to the guide portion. [Aspect 5] The plurality of guide sections comprises a left-side guide section to the left of the virtual plane and a right-side guide section to the right of the virtual plane. The plurality of guide receiving portions include a left-side guide receiving portion located to the left of the virtual plane and a right-side guide receiving portion located to the right of the virtual plane. [Aspect 6] The handle comprises a left portion and a right portion connected to each other in a left-right direction perpendicular to the front-rear direction and the up-down direction, The at least one second biasing member includes a left spring and a right spring, The left-side spring is positioned between the left-side portion and the tool body. The right-side spring is positioned between the right-side portion and the tool body. [Aspect 7] The striking tool further comprises a left spring holder connected to one of the tool body and the left portion, and a right spring holder connected to one of the tool body and the right portion. The left spring is positioned between the other side of the tool body and the left portion and the left spring holder. The right-side spring is positioned between the other side of the tool body and the right-side portion and the right-side spring holder. [Explanation of symbols]

[0101] 1A, 1B, 1C: Hammer drill, 2A: Tool body, 21: Gear housing, 22: Rear end, 221, 222, 223, 224: First connecting part, 23: Motor housing, 24: Front part, 241, 242, 243, 244: Second connecting part, 24s: Outer surface, 28: Guide part, 29: Guide plate, 26: Rear part, 261: Corner part, 263: Top wall, 265: Front wall, 266: Rear wall, 27: First spring retaining part, 271: Contact surface, 272: Retaining wall, 3A: Handle, 30: Gripping part, 30L: Left side part, 30R: Right part, 31: Cover part, 311: Opening, 33: First spring holding part, 331: Contact surface, 332: Retaining wall, 34: Guy 35, 35B, 35C: 2nd spring holding part, 351: Contact surface, 352: Holding wall, 36B: 2nd spring holding part, 361: Contact surface, 39: Grip part, 391: Upper end, 392: Lower end, 4L, 4R: Spring holder , 41: First locking part, 42: Outer wall, 42s: Outer surface, 43: Support part, 431: First surface, 44: Rear wall, 441: Front surface, 442: Rear surface, 45: Engaging part, 46: Protruding part, 51: First biasing spring, 511: Front end, 512: Rear end, 52L, 52R, 52B, 52C: Second biasing spring, 521: Front end, 522: Rear end, 61, 62: Hole, 622: Opening, 63L, 63R: Holder receiving part, 621: Second locking part, 631: First surface, 6 32: Second surface, 71: Motor, 711: Motor shaft, 72: Fan, 75: Drive mechanism, 751: Motion conversion mechanism, 752: Impact mechanism, 753: Rotation transmission mechanism, 79: Tool holder, 91: Bellows member, 92: Trigger, 93: Switch, 94: Power cord, 95: Screw, 952: Rear end, 96: Lever, 101: Tip tool, A1: Drive shaft, A2: Rotation shaft, L1: Distance, L2: Distance, P1: Virtual plane, P2: Virtual plane

Claims

1. A striking tool configured to drive the tip tool in a linear direction, Motor and, A drive mechanism configured to drive the tip tool along a drive shaft that defines the front-to-back direction of the striking tool using the power of the motor, A tool body that houses the motor and the drive mechanism and extends in the front-rear direction, A handle, including a gripping portion, extends vertically perpendicular to the front-to-back direction at the rear of the tool body, with its lower end being a free end, and is positioned below the drive shaft. The tool body and the handle are elastically connected, and a plurality of biasing members are configured to bias the tool body and the handle so that they move away from each other in the front-rear direction, The aforementioned multiple biasing members are At least one first biasing member is positioned above the drive shaft in the vertical direction, The system comprises at least one second biasing member positioned below the drive shaft in the vertical direction, The biasing force provided by the at least one second biasing member is greater than the biasing force provided by the at least one first biasing member. The at least one first biasing member and the at least one second biasing member are all of the same specifications. The number of the at least one second biasing member is greater than the number of the at least one first biasing member. Striking tools.

2. A striking tool according to claim 1, The number of the at least one first biasing member is 1. A striking tool wherein the number of the at least one second biasing member is two.

3. The striking tool according to claim 2, The two second biasing members are arranged symmetrically with respect to a virtual plane that includes the drive shaft and extends in the vertical direction, in the striking tool.

4. A striking tool configured to drive the tip tool in a linear direction, Motor and, A drive mechanism configured to drive the tip tool along a drive shaft that defines the front-to-back direction of the striking tool using the power of the motor, A tool body that houses the motor and the drive mechanism and extends in the front-rear direction, A handle, including a gripping portion, extends vertically perpendicular to the front-to-back direction at the rear of the tool body, with its lower end being a free end, and is positioned below the drive shaft. The tool body and the handle are elastically connected, and a plurality of biasing members are configured to bias the tool body and the handle so that they move away from each other in the front-rear direction, The aforementioned multiple biasing members are At least one first biasing member is positioned above the drive shaft in the vertical direction, The system comprises at least one second biasing member positioned below the drive shaft in the vertical direction, The biasing force provided by the at least one second biasing member is greater than the biasing force provided by the at least one first biasing member. The spring constant of the at least one second biasing member is greater than the spring constant of the at least one first biasing member. The number of the at least one first biasing member and the at least one second biasing member are the same. Striking tools.

5. A striking tool configured to drive the tip tool in a linear direction, Motor and, A drive mechanism configured to drive the tip tool along a drive shaft that defines the front-to-back direction of the striking tool using the power of the motor, A tool body that houses the motor and the drive mechanism and extends in the front-rear direction, A handle, including a gripping portion, extends vertically perpendicular to the front-to-back direction at the rear of the tool body, with its lower end being a free end, and is positioned below the drive shaft. The tool body and the handle are elastically connected, and a plurality of biasing members are configured to bias the tool body and the handle so that they move away from each other in the front-rear direction, The aforementioned multiple biasing members are At least one first biasing member is positioned above the drive shaft in the vertical direction, The system comprises at least one second biasing member positioned below the drive shaft in the vertical direction, The biasing force provided by the at least one second biasing member is greater than the biasing force provided by the at least one first biasing member. The at least one second biasing member is positioned between the tool body and the handle with a larger initial load applied to it than the at least one first biasing member. The number of the at least one first biasing member and the at least one second biasing member are the same. The at least one first biasing member and the at least one second biasing member are all of the same specifications. Striking tools.

6. A striking tool according to any one of claims 1 to 5, A striking tool wherein the at least one second biasing member is provided in front of the at least one first biasing member.

7. A striking tool according to any one of claims 1 to 5, The tool body includes a motor housing located at the rear of the tool body that houses the motor. The handle includes a cover portion that at least partially surrounds the motor housing, A striking tool in which the upper end of the gripping portion is connected to the cover portion.

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