Oil units and power tools

Abstract

To prevent a tube in a case from blocking a lubrication port effectively.SOLUTION: An oil unit 5 includes: a unit case 9 which may contain an oil; a blade 73 disposed inside the unit case 9; a spindle 37 which holds the blade 73 and protrudes from the unit case 9; a screw hole 44 formed at the unit case 9; and a hollow tube 48 disposed on a front inner surface 47a of a front chamber 47 in which the screw hole 44 is open in the unit case 9. A periphery of an opening 44a of the screw hole 44 on the front inner surface 47a is provided with a rib 52 which positions the tube 48 at a predetermined position to secure a passage of the oil flowing from the opening 44a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an oil unit used for outputting impact torque in a power tool such as a soft impact driver, and to a power tool using the oil unit. [Background technology]

[0002] In power tools such as soft impact drivers that use an oil unit, the rotation of the motor is output from the spindle as intermittent impulse torque (impact) by the oil unit. A known example of this oil unit is the structure disclosed in Patent Document 1. In this structure, the rear portion of the spindle is rotatably housed in a case filled with oil and through which the rotation of the motor is transmitted. A cam that rotates integrally with the case is inserted into the rear portion of the spindle, and a pair of balls and blades are housed outside the cam in the rear portion so that they can move radially. In this oil unit, when the case rotates, the cam integrated with it also rotates, pushing the blade radially outward via balls within the rear section. When the cam seals the rear section at a specified phase of the case, the oil pressure causes the blade to remain in the pushed-out position. A protrusion within the case collides with the blade, generating an impact torque. As the cam continues to rotate along with the case, the oil within the rear flows out, reducing the oil pressure, causing the blade to retreat to the rear and overcome the protrusion relatively. This repeated pushing of the blade, collision with the protrusion, and retreat generates intermittent impacts. There are also known oil units that do not use balls or other devices, but instead generate impacts by swinging the blade within the case due to the relative rotation of the case and spindle, changing the oil pressure.

[0003] In addition, in this oil unit, multiple screw holes are formed through the front part of the case, etc., in order to fill the inside of the case with oil, and a screw is screwed into each screw hole to serve as a stopper. When filling with oil, the screws are removed to open the screw holes, and the oil unit is immersed in oil, etc. Then, oil enters through some of the screw holes and air escapes through the other screw holes, and oil is poured into the case. Meanwhile, in an oil unit, continuous operation causes the oil temperature to rise and expand, increasing the internal pressure of the case. To prevent oil leakage due to this increase in internal pressure, a hollow tube made of rubber or other material is provided inside the case. This tube contracts as the internal pressure of the case increases and returns to its original shape as the internal pressure decreases, thereby absorbing the change in oil volume. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-122906 Summary of the Invention [Problem to be solved by the invention]

[0005] This tube is located behind the threaded hole (oil filler port) in the case. Therefore, depending on the position of the tube, it can block the oil filler port from the inside or narrow the flow area, reducing oil filling performance. This can make it impossible to use high-viscosity oils or restrict the tube's structure. Measures that have been taken include gluing both ends of the tube together and arranging it in a ring shape inside the oil filler port, or creating a groove on the inside of the case into which the tube fits, but these are not sufficient to prevent the tube from shifting, and there is still a risk of it blocking the oil filler port.

[0006] Therefore, an object of the present disclosure is to provide an oil unit and a power tool that can effectively prevent the tube inside the case from blocking the oil filler port. [Means for solving the problem]

[0007] In order to achieve the above object, a first configuration of the present disclosure is an oil unit, comprising: a case capable of sealing oil therein; a blade disposed inside the case; an output shaft that holds the blade and protrudes from the case; At least one oil inlet formed in the case; The oil supply port may include a hollow tube disposed on the inner surface of the case where the oil supply port opens. The oil unit is provided with a flow path forming means around the opening on the inner surface for positioning the tube at a predetermined position to ensure a flow path for oil flowing in from the opening. And, The flow path forming means is a plurality of protrusions provided on the inner surface. may be. To achieve the above object, a second configuration of the present disclosure may be a power tool that includes the oil unit of the first configuration. [Effects of the Invention]

[0008] According to the present disclosure, a flow path forming means The protrusion that becomes By adopting this, it is possible to effectively prevent the tube inside the case from blocking the oil inlet from the inside or narrowing the flow area, and there are no restrictions on the viscosity of the oil or the structure of the tube. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a central vertical cross-sectional view of the soft impact driver. [Figure 2] FIG. 2 is an enlarged vertical cross-sectional view of the center of the oil unit. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] 4A is a perspective view of the front case from the rear, and FIG. 4B is a central vertical cross-sectional view of the front case at the position of the screw holes. [Figure 5]FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. [Figure 6] FIG. 3 is a cross-sectional view taken along line CC in FIG. 2. [Figure 7] FIG. 7A is a perspective view of the front case in the modified example from the rear, and FIG. 7B is a central vertical cross-sectional view of the front case at the position of the screw holes. [Figure 8] FIG. 10 is a central vertical cross-sectional view of an oil unit according to a modified example. [Figure 9] FIG. 9A is a perspective view from the rear of a front case in another modified example, and FIG. 9B is a central vertical cross-sectional view of the front case at the position of the screw holes. [Figure 10] FIG. 10 is a central vertical cross-sectional view of an oil unit according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] In one embodiment of the present disclosure, the flow path forming means may be a protrusion provided on the inner surface of the case. According to this configuration, the flow path forming means can be easily formed by the protrusion. In an embodiment of the present disclosure, a plurality of protrusions may be provided upright. This configuration allows the tube to be positioned reliably. In one embodiment of the present disclosure, the protrusion may position the tube on the inner surface in a position that does not block the opening. With this configuration, a flow path can be ensured even if a tube is present on the inner surface. In one embodiment of the present disclosure, the protrusion may position the tube at a distance from the inner surface. This configuration can reliably prevent the opening from being blocked by the tube. In one embodiment of the present disclosure, the oil inlet is formed on a disk-shaped front portion of the case from which the output shaft protrudes, and the protrusion may extend on the inner surface of the front portion parallel to the radial direction of the front portion. According to this configuration, the flow of oil can be regulated by the protrusion. In an embodiment of the present disclosure, a pair of protrusions may be provided on either side of the opening in the circumferential direction of the front surface portion. This configuration can more effectively prevent the oil inlet from being blocked by the tube, and also improves the oil flow regulation effect. In an embodiment of the present disclosure, the protrusion may have a notch formed therein. This configuration makes it possible to ensure a large flow passage area. In one embodiment of the present disclosure, the inner surface may be formed with a recess communicating with the flow path. This configuration promotes the flow of oil toward the recessed portion. In one embodiment of the present disclosure, the oil inlet may be a threaded hole that is closed by a screw. With this configuration, an oil filling port that can be opened and closed can be easily obtained. [Example]

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a central vertical cross-sectional view of a rechargeable soft impact driver 1, which is an example of a power tool according to the second configuration, and Fig. 2 is an enlarged central vertical cross-sectional view of an oil unit. The term "soft impact driver" is a term defined by the applicant, and other power tool manufacturers may refer to it as an oil pulse driver or an impulse driver. In short, any tool that has an oil unit filled with oil is included in the power tool of this disclosure.

[0012] The soft impact driver 1 has a main body 2 and a grip 3. The main body 2 extends with its central axis in the front-to-rear direction, and houses a motor 4 in the rear and an oil unit 5 in the front. The grip 3 protrudes downward from the main body 2. A battery attachment section 6 is provided at the bottom end of the grip 3. A battery pack 7, which serves as a power source, can be attached to the battery attachment section 6 from the front. The housing of the soft impact driver 1 includes a main body housing 8, a unit case 9, and a unit case cover 10. The main body housing 8 integrates the rear part of the main body 2, the grip part 3, and the battery mounting part 6.

[0013] The unit case 9 has a tapered cylindrical shape, with its rear portion held by the main body housing 8 and protruding forward from the main body housing 8. A unit case cover 10 is placed over the unit case 9 from the front, in front of the main body housing 8. A rubber bumper 11 is provided at the front end of the unit case cover 10. A switch 12 is housed in the upper part of the grip portion 3. The switch 12 has a trigger 13 protruding forward. A forward / reverse switch button 14 for switching the rotation of the motor 4 is provided above the switch 12. A light 15 for illuminating the front is provided in front of the forward / reverse switch button 14. A terminal block 16 is housed within the battery mounting section 6. The terminal block 16 is electrically connected to the battery pack 7. A controller 17 is disposed above the terminal block 16. The controller 17 includes a control circuit board 18 and is disposed parallel to the terminal block 16. A switch panel 19 is disposed above the controller 17. The switch panel 19 is provided with a striking force switching button and the like.

[0014] The motor 4 is a brushless motor having a stator 20 and a rotor 21. A rotary shaft 22 provided at the axis of the rotor 21 extends in the front-rear direction. A disk-shaped gear case 23 is held in front of the motor 4 within the main housing 8. The rotating shaft 22 passes through the center of the gear case 23, with a pinion 24 provided at the front end protruding forward. The gear case 23 holds a bearing 25 that supports the rotating shaft 22. A reduction mechanism 26 is provided on the front side of the gear case 23. The reduction mechanism 26 includes an internal gear 27, three planetary gears 28, 28 . . . , and a carrier 29. The internal gear 27 is fixed integrally to the front side of the gear case 23. A cylindrical portion 30 extending forward is formed at the front end of the internal gear 27. The cylindrical portion 30 is inserted into the rear portion of the unit case 9 and connected to the unit case 9. Each planetary gear 28 is supported by a carrier 29 via a pin 31 that passes through the center. The carrier 29 is fixed to the rear surface of a rear case 36 of the oil unit 5. Each planetary gear 28 is disposed within the internal gear 27 with the pinion 24 at its center and meshes with the pinion 24.

[0015] 2, the oil unit 5 according to the first configuration includes a front case 35, a rear case 36, and a spindle 37. The oil unit 5 is coaxially rotatably supported within the unit case 9 by front and rear bearings 38, 39. The front bearing 38 is disposed between the front part of the unit case 9 and the spindle 37. The rear bearing 39 is disposed between the cylindrical portion 30 and the rear case 36. The front case 35 is cylindrical and tapers gradually toward the front. A central tube 42 extending rearward and having an axial hole 41 through which the spindle 37 passes is formed in a disk-shaped front portion 40 that forms the front surface of the front case 35. A sealing O-ring 43 is provided between the axial hole 41 and the spindle 37. A pair of threaded holes 44, 44 serving as oil inlets are formed through the front surface portion 40 radially outward of the axial hole 41. A pair of screws 45, 45 serving as plugs are screwed into the threaded holes 44, 44 from the front via O-rings 46. The center tube 42 protrudes rearward beyond the threaded holes 44, 44, and forms a ring-shaped front chamber 47 behind the front surface portion 40.

[0016] A tube 48 is housed within the front chamber 47. The tube 48 is a hollow body with both ends closed and filled with air, and as shown in FIG. 3, is housed in a C-shape in rear view surrounding the central tube 42. A partition plate 49 is provided behind the tube 48. The partition plate 49 has a plurality of notches 50, 50... on its outer periphery. A rear chamber 51 is formed behind the partition plate 49. The rear chamber 51 communicates with the front chamber 47 via the notches 50. In the front case 35, four ribs 52, 52... are erected on the front inner surface 47a of the front chamber 47. As shown in FIG. 4, the ribs 52 are arranged in pairs at a predetermined interval in the circumferential direction of the front surface portion 40, sandwiching the opening 44a of each screw hole 44. The pair of ribs 52, 52 extend parallel to the radial direction of the front surface portion 40 passing through the center of the screw hole 44. The radially inner end faces of the pair of ribs 52, 52 are located in front of and behind the approximate center of the screw hole 44 in the circumferential direction. Each rib 52 protrudes rearward to a height exceeding half the distance in the front-to-rear direction between the front inner surface 47a of the front chamber 47 and the front surface of the partition plate 49.

[0017] The tube 48 is disposed in a state where it is wound around the central tube 42 radially inside each rib 52. Therefore, the tube 48 is positioned within the front chamber 47 by abutting against the front inner surface 47a of the front chamber 47 and the front surface of the partition plate 49 in the front-rear direction, and by abutting against each rib 52 and the outer peripheral surface of the central tube 42 in the radial direction. In this state, as shown in Fig. 3, the inner portion of each opening 44a of the screw holes 44, 44 in the radial direction of the front surface portion 40 overlaps with the tube 48 in rear view, but the outer portion of each opening 44a in the radial direction does not overlap with the tube 48. Therefore, as shown by the two-dot chain arrow in Fig. 2, flow paths R are secured within the front chamber 47 so that oil can flow from each screw hole 44 into the front chamber 47 via the openings 44a.

[0018] The rear case 36 has a rear surface portion 55 and a side wall portion 56. The rear surface portion 55 is disk-shaped. The side wall portion 56 is cylindrical and protrudes forward from the periphery of the rear surface portion 55. The side wall portion 56 is screwed into the front case 35 from the rear and coupled to the front case 35. A sealing O-ring 57 is provided between the side wall portion 56 and the front case 35. The front end of the side wall 56 abuts against the partition plate 49. A step 58 against which the front surface of the partition plate 49 abuts is provided on the inner surface of the front case 35. The partition plate 49 is sandwiched and fixed between the side wall 56 and the step 58. 5, a pair of protrusions 59, 59 are formed on the inner peripheral surface of the side wall portion 56. The protrusions 59, 59 are arranged in point symmetry about the axis of the rear case 36 and protrude toward the center. The protrusions 59, 59 have a tapered cross-sectional shape whose circumferential width narrows toward the center. A receiving recess 60 is formed in the center of the rear surface 55 of the rear case 36. A cam 61 is fixed facing forward in the center of the receiving recess 60. The rear portion of the cam 61 forms a two-face width portion 62. The front portion of the cam 61 forms a flat portion 63 that gradually becomes thinner from the thickest center toward the outside in the radial direction. The two-face width portion 62 and the flat portion 63 are oriented perpendicular to the line connecting the centers of the protrusions 59, 59 in a front view.

[0019] The spindle 37 has a through hole 65 at its axis. The rear part of the through hole 65 forms an internal pressure chamber 66 located within the rear chamber 51. The internal pressure chamber 66 has a circular cross section, and a cam 61 is inserted therein so as to be able to rotate relative to the internal pressure chamber 66. The rear end of the spindle 37 is supported outside the cam 61 by a receiving recess 60 in the rear case 36. The rear portion 67 of the spindle 37 has a flat cross-sectional shape extending in the radial direction of the rear case 36. However, the longitudinal dimension of the cross-section of the rear portion 67 is shorter than the dimension between the opposing surfaces of the protrusions 59, 59 of the rear case 36. The rear portion 67 is located between the partition plate 49 and the rear surface 55 of the rear case 36. As shown in FIG. 6 , a front communication hole 68 and a rear communication hole 69 are formed at the front and rear of the rear portion 67 in the radial direction of the spindle 37, respectively. This direction is perpendicular to the radial direction in which the rear portion 67 extends. The front communication hole 68 communicates between a pressure adjustment hole 77 (described later) of the through-hole 65 and the rear chamber 51 when the rear portion 67 is in contact with the partition plate 49. The rear communication hole 69 communicates between the internal pressure chamber 66 and the rear chamber 51 when the rear portion 67 is in contact with the rear surface 55.

[0020] A pair of holes 70, 70 are formed in the rear portion 67 radially outward of the flat portion 63 of the cam 61. The holes 70, 70 are formed in the radial direction of the spindle 37 and communicate with the internal pressure chamber 66. This direction is the same as the extension direction of the rear portion 67. Balls 71, 71 are disposed in the holes 70, 70. Each ball 71 is movable radially within the hole 70 and can come into contact with the flat portion 63 of the cam 61 when it moves toward the center. A pair of retaining grooves 72, 72 are formed at both longitudinal ends of the rear portion 67. The retaining grooves 72, 72 communicate with the holes 70, 70. The retaining grooves 72, 72 are formed to penetrate the rear portion 67 in the front-to-rear direction so as to open at both longitudinal ends of the rear portion 67 and at the front and rear. A blade 73 is disposed in each retaining groove 72. Each blade 73 has a width that fits approximately within the circumferential width of the retaining groove 72 and a length that fits over the entire length of the retaining groove 72 in the front-to-rear direction. Each blade 73 is held within the retaining groove 72 so as to be movable in the radial direction of the spindle 37. When each blade 73 moves toward the center, it can come into contact with the ball 71. The radially outer end of each blade 73 is tapered, with the width decreasing as it goes radially outward.

[0021] The front end of the spindle 37 protrudes forward through the unit case 9 and the unit case cover 10. A sleeve 75 for attaching and detaching a bit B (FIG. 1) such as a driver bit is provided at the front end. The front part of the through-hole 65 is formed with a front bit insertion hole 76 into which a bit B is inserted, and a rear pressure adjustment hole 77 which has a smaller diameter than the bit insertion hole 76. A bit piece 78 which receives the rear end of the bit B is inserted into the rear end of the bit insertion hole 76. A pressure adjustment valve 79 is inserted into the pressure adjustment hole 77 behind the bit piece 78. The pressure adjustment valve 79 is screwed into the pressure adjustment hole 77 in a sealed state. The pressure adjustment valve 79 is provided to adjust the oil pressure (output) by moving axially with the screw feed that accompanies rotation operation from the front. The pressure adjustment valve 79, the front case 35, the rear case 36, the screws 45, 45, the spindle 37, etc. assembled in this manner form a sealed space S (FIG. 6) including a front chamber 47 and a rear chamber 51. Oil is sealed in this sealed space S.

[0022] When filling the oil unit 5 configured as described above, the screws 45, 45 on the front surface 40 are removed to open the screw holes 44, 44. Then, the spindle 37 is turned upward, and the oil unit 5, except for the front portion of the spindle 37, is immersed in oil. At this time, the spindle 37 is tilted slightly from the vertical. As a result, oil enters through one of the screw holes 44, which is on the lower side due to the tilt, and at the same time, air escapes through the other screw hole 44, and the oil fills the oil unit 5. At this time, the tube 48 is positioned by the rib 52 within the front chamber 47, so the oil flowing in from the screw hole 44 passes through the flow path R and enters the front chamber 47 without being obstructed by the tube 48, and is then injected into the rear chamber 51 through the notch 50 in the partition plate 49.

[0023] In the soft impact driver 1, with the bit B attached to the bit insertion hole 76 of the spindle 37, the user grasps the grip portion 3 and pulls the trigger 13. This turns on the switch 12, causing a three-phase current to be supplied from the battery pack 7 to the motor 4 via the control circuit board 18, causing the rotor 21 to rotate. This causes the rotating shaft 22 to rotate together with the rotor 21. The rotation of the rotary shaft 22 is transmitted to the planetary gears 28, 28... via the pinion 24. Then, the rotation is reduced by the planetary gears 28, 28... that revolve within the internal gear 27, and is transmitted from the carrier 29 to the rear case 36 of the oil unit 5. Therefore, the rear case 36 and the front case 35 rotate together. In the oil unit 5, the cam 61 rotates together with the rear case 36 in the direction of the arrow in Figure 5. As a result, the flat portion 63 of the cam 61 pushes the blades 73, 73 in the direction of protrusion from the rear portion 67 via the balls 71, 71. As the rotation progresses and the flat portion 63 becomes parallel to the rear portion 67, as shown in the phase in Figure 5, the flat portion 63 pushes the balls 71, 71 and the blades 73, 73 to the outermost positions.

[0024] As the rear case 36 and the cam 61 further rotate, the protrusions 59 come into contact with the blades 73. In this phase, the flat portion 63 blocks the space between the rear communicating hole 69 and the internal pressure chamber 66, increasing the oil pressure in the internal pressure chamber 66. As a result, the blades 73 are held in the pushed-out position. As a result, the protrusions 59 collide with the blades 73, generating an impact torque on the spindle 37. After the impact torque is generated, each blade 73 retreats toward the center due to the guide of the tapered portions of the protrusions 59 and the blades 73. At this time, oil in the internal pressure chamber 66 flows into the rear chamber 51 through the gaps between the components, allowing the blades 73 to retreat. As a result, the retreating blades 73 move relatively over the protrusions 59. When the protrusions 59, 59 pass the blades 73, 73, the rotation of the rear case 36 and cam 61 opens the space between the rear communicating hole 69 and the internal pressure chamber 66. Therefore, the cam 61 again pushes out the blades 73, 73 via the balls 71, 71. This repetition generates two impact torques per rotation of the rear case 36. In this way, work such as screw tightening can be performed using the bit B attached to the bit insertion hole 76 of the spindle 37.

[0025] The oil unit 5 and soft impact driver 1 of the above embodiment include a unit case 9 (an example of a case) capable of sealing oil inside, a blade 73 arranged inside the unit case 9, a spindle 37 (an example of an output shaft) that holds the blade 73 and protrudes from the unit case 9, a screw hole 44 (an example of an oil inlet) formed in the unit case 9, and a hollow tube 48 arranged on the front inner surface 47a (an example of an inner surface) of a front chamber 47 into which the screw hole 44 opens within the unit case 9. A rib 52 (an example of a flow path forming means) is provided around the opening 44a of the screw hole 44 on the front inner surface 47a to position the tube 48 at a predetermined position and ensure a flow path R for oil flowing in from the opening 44a. This configuration effectively prevents the tube 48 inside the unit case 9 from blocking the screw hole 44 from the inside or narrowing the flow path area. Therefore, there are no restrictions imposed by the viscosity of the oil or the structure of the tube.

[0026] The flow path forming means is a rib 52 (an example of a protrusion) erected on the front inner surface 47a. Therefore, the flow path forming means can be easily formed by the rib 52. A plurality of ribs 52 are provided upright. Therefore, the tube 48 can be positioned reliably. The rib 52 positions the tube 48 on the front inner surface 47a so as not to block the opening 44a. Therefore, even if the tube 48 is present on the front inner surface 47a, the flow path R can be secured. The screw hole 44 is formed in the disk-shaped front portion 40 of the unit case 9 from which the spindle 37 protrudes, and the rib 52 extends parallel to the radial direction of the front portion 40 on the front inner surface 47a of the front portion 40. Therefore, the ribs 52 can regulate the flow of oil. A pair of ribs 52 are provided on the front surface 40 in the circumferential direction thereof, with the opening 44a sandwiched between them. Therefore, it is possible to more effectively prevent the tube 48 from clogging the screw hole 44, and also to improve the oil rectification effect. The oil inlet is a threaded hole 44 that is closed by a screw 45 . Therefore, an oil filling port that can be opened and closed can be easily obtained.

[0027] In the above embodiment, the radial length of the rib is set so that the inner end face is located approximately in front of or behind the center of the screw hole in the circumferential direction, but the radial length of the rib is not limited to this. The rib may be formed so that the end face extends to a position beyond the center of the screw hole or beyond the screw hole itself.

[0028] However, the structure of the ribs that form the flow passages is not limited to the above example. 7, each rib 52A sandwiching the opening 44a is L-shaped and made up of a radial portion 90 and an axial portion 91. The radial portion 90 extends parallel to the radial direction of the front surface portion 40 on the front inner surface 47a of the front chamber 47. The axial portion 91 extends rearward on the inner peripheral surface of the front case 35 from the radially outer end of the radial portion 90. A recess 92 is formed in the front inner surface 47a of the front chamber 47 between the radially inner ends of the radial portions 90, 90 and the central tube 42. The recess 92 is formed linearly in the tangential direction to the central tube 42 so as to connect the ends of the radial portions 90, 90.

[0029] Therefore, in the oil unit 5 using this front case 35, as shown in Fig. 8, the tube 48 is positioned in the front-to-rear direction by abutting against the rear surfaces of the radial portions 90, 90 of the ribs 52A and the front surface of the partition plate 49, and in the radial direction by abutting against the axial portions 91, 91 of the ribs 52A. In this state, a gap equal to the thickness of the radial portions 90, 90 in the front-to-rear direction is formed between the opening 44a and the tube 48. This gap communicates with the recess 92. Furthermore, a gap equal to the radial thickness of the axial portions 91, 91 is formed between the inner circumferential surface of the front case 35 and the tube 48. 8, a flow path R1 is defined within the front chamber 47, through which oil flowing in from the opening 44a passes between the radial portions 90, 90, between the tube 48 and the center tube 42, and flows from the inner peripheral side of the tube 48 into the front chamber 47. Here, the recess 92 allows the oil passing through flow path R1 to also flow into the recess 92, making it easier for the oil to flow into the inner peripheral side of the tube 48. In addition, a flow path R2 is defined within the front chamber 47, through which oil flowing in from the opening 44a passes between the axial portions 91, 91, and between the tube 48 and the inner peripheral surface of the front case 35, and flows from the outer peripheral side of the tube 48 into the front chamber 47.

[0030] In this modified example, the tube 48 is also positioned by the rib 52A within the front chamber 47, so the oil flowing in from the screw hole 44 passes through the flow paths R1 and R2 without being obstructed by the tube 48, enters the front chamber 47, and is then injected into the rear chamber 51. This effectively prevents the tube 48 from blocking the screw hole 44. In particular, rib 52A positions tube 48 away from front inner surface 47a. Therefore, blocking of the opening 44a by the tube 48 can be reliably prevented. The front inner surface 47a is formed with a recess 92 that communicates with the flow path R1. Therefore, the flow of oil toward the inner periphery where the recessed portion 92 is located is promoted. In this modified example, the recess may be formed to a length such that both ends protrude beyond both ribs.

[0031] In the front case 35 shown in Fig. 9, the radial portion 90 of each rib 52A shown in Fig. 7 is shortened, and a notch 93 is provided between the radial portion 90 and the axial portion 91. The notch 93 allows communication between the ribs 52A, 52A in the circumferential direction with the front chamber 47. Therefore, as shown by the two-dot chain arrow in Fig. 10, in addition to the flow paths R1 and R2 similar to those in Fig. 7, a flow path R3 is secured between the radial portion 90 and the axial portion 91, through which oil flowing in from the opening 44a passes through the notch 93, flows circumferentially outward from between the ribs 52A, 52A, and flows into the front chamber 47. In this modified example, the tube 48 is also positioned by the rib 52A within the front chamber 47, so the oil flowing in from the screw hole 44 passes through the flow paths R1, R2, and R3 without being obstructed by the tube 48, enters the front chamber 47, and is then injected into the rear chamber 51. This effectively prevents the tube 48 from blocking the screw hole 44. In particular, since the notch 93 is formed in the rib 52A, a large flow passage area can be ensured. In this modified example, the width of the notches may be different between the ribs, and the notches may be provided in only one of the ribs, rather than both ribs.

[0032] In each of the above examples, the number of ribs provided in each screw hole is not limited to a pair, and only one of the ribs may be provided. The width and height of the ribs can be changed as needed. The ribs are not limited to being linear, but may be curved. The flow path forming means is not limited to ribs, and one or more cylindrical or prismatic protrusions may be erected around the screw holes. Multiple protrusions of different shapes may be combined. The position and number of recesses may also be changed as appropriate. The combination of protrusions and recesses may also be changed as appropriate. The positions and number of screw holes are not limited to those in the above example. For example, the screw holes may be located radially inward from those in the above example, and there may be three or more screw holes instead of one pair. However, the oil inlet is not limited to a screw hole, but may be a simple through hole, in which case a plug other than a screw may be used. The shape of the tube is not limited to the above example. The tube may be a ring that is connected all around. Furthermore, the flow passage forming means may not use ribs or protrusions, but may be configured to avoid the oil inlet by using the shape of the tube itself.

[0033] The case is not limited to a unit case consisting of a front case and a rear case as in the above example. The case may be composed of three or more parts. The case may be divided into left and right or top and bottom instead of front and back. It is not necessary to eliminate the partition and divide it into a front chamber and a rear chamber. An oil unit that does not use balls or coil springs but instead controls hydraulic pressure by swinging a blade within the case due to the relative rotation of the case and spindle can also be used. For example, one oil unit has one or more blades that are biased radially outward on the spindle, and high fluid pressure is applied intermittently to one side of the blade due to the rotation of the case that forms the oil chamber. In this structure, the blade tilts in the direction of rotation and is pressed against the spindle by being sealed by a seal provided in the case and a groove provided in the spindle, causing the spindle to rotate impulsively. The motor is not limited to a brushless motor, and a commutator motor, etc. The present disclosure is also applicable to AC tools that do not use a battery pack as a power source. The power tool is not limited to a soft impact driver, and the present disclosure can be applied to other power tools having an oil unit, since it allows oil to be easily poured into the interior of the oil unit. [Explanation of symbols]

[0034] 1 soft impact driver, 2 main body, 3 grip, 4 motor, 5 oil unit, 8 main body housing, 9 unit case, 22 rotating shaft, 26 reduction mechanism, 35 front case, 36 rear case, 37 spindle, 40 front surface, 41 shaft center hole, 42 center tube, 44 screw hole, 44a opening, 45 screw, 47 front chamber, 47a front inner surface, 48 tube, 49 partition plate, 51 rear chamber, 52, 52A rib, 61 cam, 73 blade, 90 radial portion, 91 axial portion, 92 recess, 93 notch, R, R1 to R3 flow path, B bit.

Claims

1. A case that can be filled with oil inside, a blade disposed inside the case; an output shaft that holds the blade and protrudes from the case; At least one oil inlet formed in the case; a hollow tube disposed on an inner surface of the case where the oil filling port opens, a flow path forming means is provided around the opening on the inner surface to position the tube at a predetermined position and ensure a flow path for oil flowing through the opening, The flow path forming means is an oil unit that is a plurality of protrusions provided upright on the inner surface.

2. The oil unit according to claim 1 , wherein the protrusion positions the tube on the inner surface at a position that does not block the opening.

3. The oil unit according to claim 1 or 2, wherein the protrusion positions the tube at a position spaced apart from the inner surface.

4. A case capable of sealing oil inside; a blade disposed inside the case; an output shaft that holds the blade and protrudes from the case; At least one oil inlet formed in the case; a hollow tube disposed on an inner surface of the case where the oil filling port opens, a protrusion is provided around the opening on the inner surface to position the tube at a predetermined position and ensure a flow path for oil flowing through the opening, The oil inlet is formed on the disk-shaped front portion of the case from which the output shaft protrudes, and the protrusion extends on the inner surface of the front portion parallel to the radial direction of the front portion.

5. The oil unit according to claim 4, wherein a pair of the protrusions are provided on either side of the opening in the circumferential direction of the front surface.

6. A case capable of sealing oil inside; a blade disposed inside the case; an output shaft that holds the blade and protrudes from the case; At least one oil inlet formed in the case; a hollow tube disposed on an inner surface of the case where the oil filling port opens, a protrusion is provided around the opening on the inner surface to position the tube at a predetermined position and ensure a flow path for oil flowing through the opening, The oil unit has a notch formed in the protrusion.

7. A case capable of sealing oil inside; a blade disposed inside the case; an output shaft that holds the blade and protrudes from the case; At least one oil inlet formed in the case; a hollow tube disposed on an inner surface of the case where the oil filling port opens, a protrusion is provided around the opening on the inner surface to position the tube at a predetermined position and ensure a flow path for oil flowing through the opening, The oil unit has a recess formed on the inner surface thereof, the recess communicating with the flow path.

8. 8. The oil unit according to claim 6, wherein the protrusion comprises a plurality of protrusions.

9. An oil unit described in any of claims 1, 4, 6, or 7, wherein the oil inlet is a screw hole that is blocked by a screw.

10. A power tool comprising the oil unit according to any one of claims 1, 4, 6 and 7.

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