Air Tools

Abstract

To provide an air tool that is made compact and has increased output.SOLUTION: A air tool 100 has an air filling space L that includes a rotor 31, a plurality of blades 45 provided on an outer face 37 of the rotor 31, and a cylinder 50 to accommodate the rotor 31 and the blade 45. The air filling space L has: a first space M defined by a virtual cylindrical face C including a rotor outer surface 37, adjacent two blades 45, and virtual planes D and E including an inner face 51a of a cylinder cylindrical member, and the inner faces of end members disposed at both ends of the cylinder cylindrical member; and a second space N in communication with the first space M and closed within the air tool.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an air tool having an air motor that is rotated by high-pressure air. [Background technology]

[0002] Conventionally, a hand-operated air tool has been used that rotates an air motor with high-pressure air. The air tool includes an air motor having a rotor that rotates with high-pressure air and a cylinder that houses the rotor. The rotor has a plurality of grooves that are equally spaced in the circumferential direction on its outer circumferential surface, and a plate-shaped blade is inserted into each groove so as to be slidable inward and outward. An air-filled space is formed by two adjacent blades, the rotor, and the cylinder, and high-pressure air is introduced into the air-filled space from an air inlet to rotate the rotor.

[0003] Air tools for processing materials are equipped with cutting blades, and the cutting blades are rotated by the rotational force of a rotor to process the target object. The target object includes hard materials such as metals, and air tools with higher output are required to easily process hard materials. In addition, for air tools used for tightening and loosening bolts, such as impact wrenches, it is desirable to have a higher torque to make the work easier. Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the size of the air motor is increased in order to obtain high torque and high output, the air tool also becomes large and heavy, making it difficult for the operator to handle.

[0005] The present invention has been made in order to solve the above problems, and has an object to provide an air tool that is compact and has a higher torque and power without increasing its weight. [Means for solving the problem]

[0006] The air tool of the present invention includes a rotor, a plurality of blades provided on an outer peripheral surface of the rotor, and an air-filled space formed by a cylinder that houses the rotor and the blades. The air-filled space includes a first space defined by two imaginary planes including an imaginary cylindrical surface including the outer peripheral surface of the rotor, two adjacent blades, an inner peripheral surface of a cylindrical member of the cylinder, and inner surfaces of end members disposed at both ends of the cylindrical member of the cylinder, and a second space defined by two imaginary planes that communicate with the first space and and is blocked within the air tool. a second space defined by a first groove formed in the rotor and a second space defined by a second groove formed in the rotor; a plurality of blade grooves are formed on the outer periphery of the rotor; a main body piece portion is provided between each of the plurality of blade grooves adjacent to each other in the circumferential direction of the rotor; and a recess is provided on the outer periphery of each main body piece portion, spaced apart in the circumferential direction of the rotor from the blade groove and radially recessed from the outer periphery of the main body piece portion, the recess constituting the second space. In the air tool of the present invention, the recess may have a shape in which both ends in the axial direction of the rotor are closed. In the air tool of the present invention, the recess may extend along the rotation axis of the rotor on the outer circumferential surface of the main body piece, and both ends in the axial direction of the rotor may be semicircular.

[0007] The air tool of the present invention is provided with the second space, which is a buffer space for air, thereby making it possible to reduce compression of the air in the air-filled space and thereby reduce loss of rotational energy.

[0009] In the air tool of the present invention, the recessed portion which is the buffer space for the air is Each body part Since it is formed on the outer peripheral surface, it is possible to provide an air buffer space by only making a relatively small change to the rotor.

[0010] The air tool of the present invention In the above The bottom of the recess is Perpendicular to the axial direction of the rotor cross section In arc Round shape Formed with a shape It's fine.

[0011] When forming recesses with a constant circumferential width in a rotor, the deeper the recesses are, the narrower the interval between the bottoms of adjacent recesses becomes. Since a thinner wall causes strength problems, the interval between the bottoms of adjacent recesses cannot be made too small, and the volume of the recesses is limited by the constraints on the depth of the recesses. In contrast, the recesses of the air tool of the present invention have bottoms that are arc-shaped. Round shape Since the recess is formed to include a rounded shape, it is possible to form a recess of a certain width from the rotor surface to a depth that allows for strength, and further to provide a rounded recess. Therefore, compared with a case in which the bottom of the recess is not rounded, specifically a case in which the cross section of the bottom is substantially rectangular or triangular with corners where a flat surface intersects with a flat surface or a curved surface, the recess volume can be made larger, and as a result, a larger air buffer space can be provided. 。 [Brief description of the drawings]

[0014] [Figure 1] 1 is a side view showing an air tool according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of part A of the air tool of FIG. 1, taken along a cross section passing through the rotation axis of a rotor. [Diagram 3] FIG. 2 is a cross-sectional view of FIG. [Figure 4] FIG. 3 is a perspective view of the rotor of FIG. 2. [Diagram 5] 2 is a characteristic diagram showing a change in volume of an air-filled space of an air motor provided in the air tool of FIG. 1. [Figure 6] 2 is a schematic diagram showing the operation of an air motor provided in the air tool of FIG. 1. FIG. [Figure 7] 2 is a schematic diagram showing the operation of an air motor provided in the air tool of FIG. 1. FIG. [Figure 8] 2 is a schematic diagram showing the operation of an air motor provided in the air tool of FIG. 1. FIG. [Figure 9] 2 is a schematic diagram showing the operation of an air motor provided in the air tool of FIG. 1. FIG. [Figure 10] FIG. 2 is a characteristic diagram showing the rotational torque of the air tool of FIG. [Figure 11]FIG. 2 is a characteristic diagram showing the power of the air tool of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <Embodiment> An air tool according to an embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a side view showing an air tool 100 according to an embodiment of the present invention, which is equipped with an air motor having a structure according to the present invention. FIG. 2 is a cross-sectional view of the section passing through the rotation axis X of the rotor 31 in part A of the air tool in FIG. 1. FIG. 3 is a cross-sectional view taken along line II in FIG. 2. FIG. 4 is a perspective view showing the rotor 31 in FIG. 2, which is a feature of the present invention. In this description, FIG. 3 and FIGS. 6 to 9, which are cross-sectional views of the air motor 30, all show the air tool 100 in cross sections perpendicular to the rotation axis of the rotor, as viewed from the front of the air motor 30, that is, from the left side of FIGS. 1 and 2. The rotation operation of the air tool 100 will be described in the case of left rotation as viewed from the operator, that is, in the direction of loosening a right-threaded bolt.

[0016] An air tool 100 will be described with reference to FIG. 1. The air tool 100 is an impact wrench, and the present invention will be described in the case of being applied to an impact wrench. The air tool 100 includes a housing 10 and an air motor 30. The role of the recess of the air tool of the present invention will be described. In the air tool 100, after air is introduced into the air-filled space L, the volume of the air-filled space L sandwiched between the blades 45 gradually decreases with the rotation of the rotor 31, and the air is exhausted. The inventor of the present invention has found that the amount of exhaust from the exhaust port is saturated at that time, and the air in the air-filled space L is compressed, and when the air in the air-filled space L is compressed, a loss of rotational energy occurs. In the present invention, by providing a second space N, which is a buffer space for air, the compression of the air in the air-filled space L can be reduced, thereby reducing the loss of rotational energy.

[0017] The present invention can be applied to various air tools other than impact wrenches, so long as the air tool is equipped with an air motor 30. For example, the present invention can be applied to drills, grinders, ratchet wrenches, etc. The air tool 100 has the following structure as an impact wrench.

[0018] The housing 10 has an upper housing 11 which houses the air motor 30 therein, a lower housing 12 which is disposed below the upper housing 11, and a front housing 13 which is attached to the front side of the upper housing 11.

[0019] The lower housing 12 is provided with a grip 21, an air inlet 22 provided at the bottom end of the lower housing 12, and a throttle 23 that continuously adjusts the flow rate of high-pressure air introduced into the front end of the lower housing 12 to the air motor 20. The air inlet 22 is a portion to which a hose end is connected, and high-pressure air is supplied to the air tool 100 from the outside via the air inlet 22.

[0020] The inside of the front housing 13 is not shown, but as is well known, the front housing 13 accommodates a pair of hammers (not shown), a hammer frame that rotatably holds the hammers, and anvil 25 to which rotational force is transmitted from rotor 31. From an opening provided at the tip of the front housing 13, the tip of the anvil 25 to which a hexagonal socket can be attached protrudes.

[0021] The internal structure of the upper housing 11 will be described with reference to Figs. 2 to 4. Fig. 2 is a partial cross-sectional view of part A, which includes the rotation axis X of the rotor 31 of the air motor 30 and is parallel to the vertical direction of the air tool 100. Fig. 3 is a cross-sectional view taken along line II in Fig. 2. Fig. 4 is a perspective view of the rotor 31 included in the air tool 100. The air motor 30 housed in the upper housing 11 has the rotor 31, a plurality of blades 45 incorporated in the rotor 31, a plurality of bearings 46 which rotatably hold the rotor 31, and a cylinder 50 which houses the rotor 31 therein.

[0022] As shown in FIG. 2, the cylinder 50 is a member in which a plurality of members are assembled to form a space in which the rotor 31 is housed. The cylinder 50 has a cylindrical member 51 having an approximately cylindrical shape and an inner peripheral surface 51a, a first end member 52 having an approximately disk shape and an inner surface 52a, and a second end member 53 having an approximately disk shape and an inner surface 53a. The cylinder 50 is fixed inside the upper housing 11 with the outer peripheral ends of the first end member 52 and the second end member 53 fitted into the inner surface of the upper housing 11. The cylindrical member 51 has a space therein in which the rotor 31 is housed. The first end member 52 is disposed at the end of the cylindrical member 51 on the anvil 25 side, and the second end member 53 is disposed at the end of the cylindrical member 51 opposite to the anvil 25, so as to close both ends of the cylindrical member 51. In this embodiment, the cylindrical member 51 and the second end member 53 are integrally formed into a bottomed cylindrical shape with the second end member 53 as the bottom portion. A through hole is provided in the central portion of each of the first end member 52 and the second end member 53, and bearings 46, 46 are disposed on the outside of each through hole.

[0023] As shown in FIG. 3, the second end member 53 is provided with a ventilation port for sucking and exhausting air inside the cylinder 50. In the cross-sectional view of FIG. 3, a first communication port 55 is provided in the upper right portion, and a third communication port 57 is provided in the upper left portion. In addition, a second communication port 56 is provided at a substantially intermediate position between the first communication port 55 and the third communication port 57 in the rotation direction of the rotor 31 of the cylindrical member 51. The air tool 100 is configured so that the rotation direction of the rotor 31 can be selected in one direction or the other direction. The air tool 100 is provided with an air flow path switching mechanism (not shown), and can switch between communicating the first communication port 55 and the third communication port 57 with the air inlet 22 or communicating with the exhaust outlet to the outside. The rotation direction of the air tool 100 can be switched as necessary, such as tightening and loosening a bolt.

[0024] 2, the rotor 31 is a member having a shape in which a first rotating shaft support portion 33 and a second rotating shaft support portion 34 protrude from both end faces of a substantially cylindrical member. The rotor 31 has a rotor body 32, a first rotating shaft support portion 33 formed to protrude from the rotor body 32 toward the anvil 25 side, and a second rotating shaft support portion 34 formed to protrude from the rotor body 32 to the side opposite the anvil 25 side. The first rotating shaft support portion 33 and the second rotating shaft support portion 34 are portions held by bearings 46, 46 fixed to a cylinder 50. The rotor body 32, the first rotating shaft support portion 33, and the second rotating shaft support portion 34 are arranged so that their respective rotation axes X are aligned.

[0025] The shape of the rotor 31 will be further described with reference to Figs. 3 and 4. The rotor body 32 has a substantially cylindrical shape and includes a first end face 35 which is an end face on the anvil 25 side, a second end face 36 which is an opposite face to the first end face 35, and an outer circumferential face 37 between the first end face 35 and the second end face 36. The rotor body 32 is provided with a plurality of blade grooves 38 at regular angles in the circumferential direction centered on the rotation axis X. The blade grooves 38 are grooves which slidably hold the blades 45. The blade grooves 38 are formed with a constant groove width from the outer circumferential face 37 toward the rotation axis X of the rotor body 32, and the blade grooves 38 are provided linearly over the entire length of the rotor body 32 in the direction of the rotation axis X from the first end face 35 to the second end face 36. The number of blade grooves 38 is appropriately determined from 4 to 8, and in this embodiment, for example, six blade grooves are provided. The blade grooves 38 are provided in the rotor body 32 at regular angular intervals in the circumferential direction around the rotation axis X, and thus a main body piece portion 39 is formed in a portion sandwiched between two adjacent blade grooves 38. The number of main body piece portions 39 provided is the same as the number of blade grooves 38. For example, when six blade grooves 38 are provided, six main body piece portions 39 are also provided. In addition, in the case of an air tool in which the rotor rotates in only one direction, for example, four blade grooves 38 may be provided.

[0026] A blade 45 is inserted into each blade groove 38. As shown in FIG. 3, the blade 45 is formed in a similar shape to the blade groove 38 and is inserted into the blade groove 38. The blade 45 is a plate-like member of a substantially rectangular shape with a constant thickness, and is formed into a substantially convex curved circle with the central portion of one long side bulging outward. The circumferential width of the blade groove 38 is formed to be 1% to 5% larger than the thickness of the blade 45, and the blade 45 is accommodated in the blade groove 38 with a clearance fit. The blade 45 moves to the outer periphery side in the blade groove 38 due to the centrifugal force caused by the rotation of the rotor 31 to a position where the outer end of the blade 45 comes into contact with the inner periphery surface 51a of the cylindrical member. The distance B between the outer periphery surface 37 of the rotor 31 and the inner periphery surface 51a of the cylindrical member 51 of the cylinder 50 changes periodically from 0 to a maximum value Bmax due to the rotation of the rotor 31. 3, the distance indicated by B is the maximum value Bmax of distance B, and the distance B at a position rotated 180° circumferentially from that position is 0. Therefore, the amount of protrusion of blade 45 from blade groove 38 periodically changes from 0 to the maximum value Bmax in response to the periodic change in distance B accompanying the rotation of rotor 31.

[0027] The main body piece portion 39 has a recess 40. The recess 40 is formed with a constant circumferential width from the outer peripheral surface 37 of the main body piece portion 39 toward the rotation axis X of the rotor body 32. The recess 40 has both recess end portions 42 and an intermediate portion 41 formed between both recess end portions 42. Regarding the shape of the opening of the recess 40 on the outer peripheral surface 37, the intermediate portion 41 is defined by two straight portions parallel to each other, and the recess end portion 42 is formed so that a semicircular shape connects the two straight portions. As shown in FIG. 3, the shape of the bottom portion 43 of the recess 40 in a cross section perpendicular to the rotation axis X of the rotor body 32 is formed into a semicircular round portion. Moreover, the shape of the bottom portion 43 of the recess end portion 42 of the recess 40 is formed into a semicircular round portion in a cross section parallel to the rotation axis X of the rotor body 32. That is, the bottom portion 43 of the recess 40 does not have a corner formed by the intersection of a flat surface with a flat surface or a curved surface, and is formed only in a round shape. This allows the circumferential width of the recess 40 to be increased, thereby expanding the settable dimensional range of the recess 40. As a result, stress concentration at the bottom 43 of the recess 40 is reduced compared to when a corner is formed at the bottom 43 of the recess 40 by intersecting a flat surface with a flat surface or a curved surface.

[0028] The dimensions of the recess 40 will be described. The circumferential width of the recess 40 is 20% to 80%, preferably 30% to 70%, and more preferably 40% to 60% of the circumferential width of the main body piece portion 39. The depth of the recess 40 is 20% to 80%, preferably 30% to 70%, and more preferably 40% to 60% of the radius of the rotor body 32. Since the recess 40 is formed by cutting the main body piece portion 39, the dimensions of the recess 40 are determined by comprehensively taking into account the dimensional range possible in terms of strength, the required volume of the recess 40, and the like.

[0029] The air-filled space L will be described with reference to FIG. 2 and FIG. 3. The first space M is a space surrounded by the imaginary cylindrical surface C, the cylindrical member inner peripheral surface 51a, the imaginary plane D including the inner surface 52a of the first end member 52, and the imaginary plane E including the inner surface 53a of the second end member 53. The second space N is an internal space of the recess 40 provided in the main body small piece portion 39 of the rotor main body 32, that is, a space surrounded by the imaginary cylindrical surface C including the outer peripheral surface 37 of the rotor main body 32 and the inner surface of the recess 40. Therefore, the air-filled space L filled with high-pressure air is the sum of the first space M and the second space N. As shown in FIG. 3, the volume of the first space M changes with the rotation of the rotor 31. Specifically, the volume of the air-filled space L is minimum when the air-filled space L is at the upper right position in FIG. 3 and adjacent to the first communication port 55, and the volume of the air-filled space L increases as the rotor 31 rotates rightward in FIG. 3 until it reaches the position directly below in FIG. 3. Thereafter, with further rotation, the air filled space L decreases, and the volume of the air filled space L becomes minimum when the air filled space L reaches the upper left position in Fig. 3 adjacent to the third communication port 57. Note that the first space M communicates with the first communication port 55, the second communication port 56, or the third communication port 57, which are always in communication with the outside, depending on the rotational position of the rotor 31, but the first space M does not include the spaces of the above communication ports and is defined as above.

[0030] With reference to FIG. 5, the change in the volume of the air-filled space L caused by the rotation of the rotor 31 will be described. FIGS. 6 to 9 show the movement of one air-filled space L, indicated by a dot pattern, from the introduction of high-pressure air to the exhaust thereof, caused by the rotation of the rotor 31. FIG. 6 shows the introduction process of high-pressure air, in which one air-filled space L is in communication with the first communication port 55. FIG. 7 shows the expansion process, after FIG. 6, in which the air-filled space L expands as the rotor rotates. FIG. 8 shows the compression process, after FIG. 7, in which the air-filled space L starts to compress as the rotor rotates and communicates with the second communication port 56. FIG. 9 shows the exhaust process, after FIG. 8, in which the air-filled space L communicates with the third communication port 57 as the rotor rotates.

[0031] The present invention reduces energy loss that occurs when the air filling space L becomes saturated with the exhaust amount during the compression process to the exhaust process, compressing the air in the air filling space L. FIG. 5 shows theoretical values ​​of changes in the air filling space L in the range of rotor rotation angles of 120° from the compression process shown in FIG. 8 to the exhaust process shown in FIG. 9. Diagram 1 in FIG. 5 is a diagram of specification 1 in which the rotor 31 does not have a recess 40. Diagrams 2 to 4 are diagrams of specifications 2 to 4 in which the rotor 31 is provided with a recess 40. Specifications 2 to 4 are specifications in which the main body small piece 39 is provided with recesses 40 of volumes equivalent to 10%, 20%, and 30% of the volume of the main body small piece 39 in the absence of the recess 40, respectively. FIG. 5 shows the volume ratio of the air filling space L due to the change in rotation angle thereafter, with the air filling space L at the compression process point in FIG. 8 being set to 1.

[0032] In the specification 1, the volume ratio is about 0.43 when rotated 60° from FIG. 8, and 0.05 when rotated 120° from FIG. 9. In contrast, in the specification 2, the volume ratio is about 0.45 when rotated 60° from FIG. 8, and 0.15 when rotated 120° from FIG. 9. In the specification 3, the volume ratio is about 0.48 when rotated 60° from FIG. 8, and 0.21 when rotated 120° from FIG. 9. In the specification 4, the volume ratio is about 0.49 when rotated 60° from FIG. 8, and 0.29 when rotated 120° from FIG. 9. As can be seen from the graph in FIG. 5, the larger the volume of the recess 40 provided in the main body small piece portion 39, the smaller the volume change from the compression stroke point in FIG. 8. Also, the closer the rotor 31 is to the exhaust stroke shown in FIG. 9, the smaller the degree of volume change. It is believed that it has been theoretically confirmed that in conventional air motors, by providing a recess 40 in the main body piece portion 39 in addition to the second communication port 56 provided prior to the third communication port 57, it is possible to reduce the energy loss generated by compressing the air in the air-filled space L.

[0033] The graphs in Figures 10 and 11 respectively show the rotational torque and power measured for a prototype air motor 30 having a main body piece 39 with a recess 40. The volume of the recess 40 in the prototype air motor 30 is equivalent to 22% of the volume of the main body piece 39 without the recess 40. The measurement results were compared between an air motor 30 with a recess 40 of the above size and an air motor without a recess 40. The table below shows the rate of increase in rotational torque and power at representative rotation speeds. [Table 1]

[0034] 10 and 11, it was confirmed that the rotational torque and power of the product of the present invention are increased compared to the conventional air motor 30 without the recess 40. At 4,000 rpm, the rotational torque and power are increased by 5%. At 6,000 rpm and above, the rotational torque and power are increased by more than 10%, and the product of the present invention was able to improve the rotational torque and power in both low and high rotational speed ranges.

[0035] <Modification> In the above embodiment, the recess 40 serving as an air buffer to reduce energy loss is provided on the outer circumferential surface 37 of the rotor 31. Alternatively, the second space serving as an air buffer may be provided in the cylinder 50. The recess serving as the second space may be provided on the inner circumferential surface 51a of the cylindrical member 51 of the cylinder 50. Alternatively, the second space may be provided on the inner surface 52a, 53a of the first end member 52 or the second end member 53 of the cylinder 50. The second space provided in the cylinder 50 is provided at a position communicating with the air filling space L when the air filling space L is in the compression stroke. Also, the second space provided in the cylinder 50 is provided as a closed space not communicating with the outside. That is, the second space may be provided in one or more of the inner circumferential surface 51 a of the cylindrical member 51, the inner surface 52 a of the first end member 52 of the cylinder 50, and the inner surface 53 a of the second end member 53, which communicate with the first space and do not communicate with either the second communication port 56 or the third communication port 57 in a rotation angle range in which the rotor 31 is located behind the second communication port 56 and before the third communication port 57.

[0036] According to the present invention, it is possible to provide an air tool that can be made smaller and has increased output. [Explanation of symbols]

[0037] 30 air motor, 31 rotor, 37 rotor outer peripheral surface, 40 recess, 45 blade, 50 cylinder, 51 cylindrical member, 52, 53 end members, 100 air tool, L air filling space.

Claims

[Claim 1] 1. An air tool comprising: a rotor; a plurality of blades provided on an outer peripheral surface of the rotor; and an air-filled space formed by a cylinder that houses the rotor and the blades, the air-filled space is a first space defined by two imaginary planes including an imaginary cylindrical surface including the rotor outer peripheral surface, two adjacent blades, an inner peripheral surface of a cylindrical member of the cylinder, and inner surfaces of end members disposed at both ends of the cylindrical member of the cylinder; a second space communicating with the first space and closed within the air tool; A plurality of blade grooves are formed on an outer periphery of the rotor, and a main body piece portion is provided between each of the plurality of blade grooves adjacent to each other in a circumferential direction of the rotor, An air tool characterized in that a recess is provided on the outer peripheral surface of each main body piece portion, spaced circumferentially from the blade groove in the circumferential direction of the rotor and recessed radially from the outer peripheral surface of the main body piece portion, and the recess constitutes the second space.

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