Impact torque generator for hydraulic torque wrench

Abstract

To provide an impact torque generator for a hydraulic torque wrench which eliminates a need for blades that are constantly urged by a spring in a direction of an outer periphery of a main shaft, has low sliding resistance, is excellent in energy efficiency, has a small temperature rise of hydraulic oil to obtain stable output, and is small, simple in structure, and durable.SOLUTION: Two seal surfaces 31a, 31b of a liner 31 are formed at positions of 180° rotational symmetry of a hollow part. When the seal surfaces 31a, 31b of the liner 31 and one seal surface of each of driving blades 34a, 34b coincide with each other, the other seal surface comes into slide contact with an inner peripheral surface of the hollow part to seal, and thereby the inside of the liner 31 is divided into a high pressure chamber H and a low pressure chamber L by the driving blades 34a, 34b so that a main shaft 9 generates impact torque.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to an impact torque generating device for a hydraulic torque wrench. [Background technology]

[0002] Hydraulic torque wrenches that use hydraulic impact torque generators that produce less noise and vibration as impact torque generators for torque wrenches have been developed and are now in practical use. Figure 19 shows an example of such a hydraulic torque wrench. The hydraulic torque wrench's body 1 includes a main valve 2 that switches the supply and stop of high-pressure air and a forward / reverse rotation switching valve 3 that selectively generates forward and reverse impact torque. The high-pressure air supplied through these valves 2 and 3 drives a rotor 4, which generates rotational torque. A hydraulic impact torque generator 5 that converts the rotational torque of the rotor 4 into impact torque is housed in a front case 6 protruding from the tip of the hydraulic torque wrench's body 1. This hydraulic impact torque generator 5 includes a liner 8 housed in a liner case 7, which is filled and sealed with hydraulic oil. A main shaft 9 coaxially inserted within the liner 8 has one or more blade insertion grooves, into which blades B are inserted. The blades B are constantly biased toward the outer periphery of the main shaft by a spring S, abutting against the inner circumferential surface of the liner 8 and forming one or more sealing surfaces on the outer periphery of the main shaft 9. The liner 8 is also equipped with an output adjustment mechanism 10 that adjusts the magnitude of the impact torque. Then, by rotating the liner 8 with the rotor 4, when the multiple seal surfaces formed on the inner surface of the liner 8 come into contact with the seal surfaces formed on the outer surface of the main shaft 9 and the blades B, an impact torque is generated on the main shaft 9.

[0003] Incidentally, in the case of the impact torque generator of a conventional hydraulic torque wrench, one or more blade insertion grooves are provided in the main shaft 9, and blades B are inserted into these blade insertion grooves, and these blades B are constantly urged toward the outer periphery of the main shaft by springs S to abut against the inner circumferential surface of the liner 8. This has resulted in large energy loss due to sliding resistance between the tips of the blades B and the inner circumferential surface of the liner 8, and has also caused problems such as a rise in the temperature of the hydraulic oil due to frictional heat generated by this sliding, and changes in the viscosity of the hydraulic oil causing fluctuations in the output of the torque wrench. Furthermore, since it is necessary to provide holes in the main shaft 9 for inserting the blade insertion grooves and springs S, the diameter of the main shaft 9 must be increased in order to maintain the strength of the main shaft 9, which results in an increase in the size and complexity of the device itself, as well as problems with the durability of the device, such as damage to the springs S.

[0004] In order to address this problem, the applicant of the present invention previously proposed an impact torque generator for a hydraulic torque wrench that eliminates the blade B that is constantly biased toward the outer periphery of the spindle by a spring S, thereby reducing sliding resistance and improving energy efficiency, minimizing the temperature rise of the hydraulic oil, providing stable output, and being compact, simple in structure, and durable (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-328944 [Patent Document 2] Japanese Patent Application Publication No. 2019-42919 Summary of the Invention [Problem to be solved by the invention]

[0006] The basic structure of this hydraulic torque wrench is the same as that of the conventional hydraulic torque wrench shown in Figure 19. The hydraulic torque wrench has a main valve 2 that supplies and stops high-pressure air and a forward / reverse rotation switching valve 3 that selectively generates forward / reverse rotation impact torque. A rotor 4 that generates rotational torque is driven by high-pressure air sent from 2 and 3. A hydraulic impact torque generator 5 that converts the rotational torque of the rotor 4 into impact torque is provided inside a front case 6 that protrudes from the tip of the main body 1 of the hydraulic torque wrench.

[0007] As shown in FIGS. 1 to 6, the hydraulic impact torque generator 5 has a liner 11 provided in a liner case 7, the liner 11 filled with hydraulic oil and sealed, and the main shaft 9 inserted coaxially into the liner 11.

[0008] The liner 11, into which the main shaft 9 is inserted, has a generally elliptical cavity formed therein, and four pairs of seal surfaces 11a, 11b are formed in a mountain-like shape on its inner circumferential surface. These pairs of seal surfaces, i.e., seal surfaces 11a and 11b, are positioned at 180° rotational symmetry. The outer periphery of the cylindrical liner 11 is supported by the liner case 7, and an upper liner cover 12 and a lower liner cover 13 are disposed on both ends of the liner 11. The liner 11, the upper liner cover 12, and the lower liner cover 13 are configured to rotate integrally by inserting knock pins 17 into pin holes formed in the liner 11 and pin holes 12a, 13a formed in the upper liner cover 12 and the lower liner cover 13, respectively. The upper liner cover 12 is further fixed in the axial direction by the liner case cover 7a, sealing the hydraulic oil filled inside the liner 11.

[0009] The main shaft 9, which is coaxially disposed inside the liner 11, has two projections 15a and 15b, each having a smooth surface, formed at positions that are rotationally symmetrical by 180°. The two protrusions 15a, 15b of this main shaft 9 are configured so that their axial and circumferential lengths are both shorter than the hollow portion inside the liner 11, thereby forming passages through which hydraulic oil flows at both axial ends and the circumferential tip.

[0010] Two driving blades 14a, 14b of the same size and with a smooth surface and a roughly triangular cross section are inserted into a hollow formed inside liner 11 and partitioned by protrusions 15a, 15b of main shaft 9. The two driving blades 14a, 14b are formed with axial lengths that are approximately the same as the hollow inside liner 11 so that the side surfaces of driving blades 14a, 14b come into sliding contact with the inner surfaces of liner upper cover 12 and liner lower cover 13, and are formed with sealing surfaces near both ends that correspond to sealing surfaces 11a, 11b of liner 11, so that sealing surfaces 11a, 11b of liner 11 and the sealing surfaces of driving blades 14a, 14b come into contact twice per rotation of liner 11.

[0011] The outer peripheral surface of the liner 11 is provided with a communication groove 16 that interconnects the hollow portions that become the low-pressure chamber L inside the liner 11 defined by the driving blades 14a, 14b and the sealing surfaces 11a, 11b of the liner 11.

[0012] The liner 11 is also provided with an output adjustment mechanism 10 that adjusts the magnitude of the impact torque parallel to the axis of the liner 11. This output adjustment mechanism 10 is a conventionally known mechanism, and is composed of ports 10a and 10b that communicate between a cavity that becomes a high-pressure chamber H and a cavity that becomes a low-pressure chamber L inside the liner 11, which are partitioned by driving blades 14a and 14b and sealing surfaces 11a and 11b of the liner 11, and an output adjustment valve 10c that is adjustably screwed into a screw hole 13b provided in the liner bottom cover 13.

[0013] To explain the operation of the impact torque generator 5 of this hydraulic torque wrench, first, the main valve 2 and the switching valve 3 are operated to introduce high-pressure air into the rotor chamber in the main body 1, causing the rotor 4 to rotate at high speed. The rotational force of this rotor is transmitted to the liner 11.

[0014] As the liner 11 rotates, the inside of the liner case 7 flows in the order of FIG. 6(a)→(b)→(c). 6(a) shows a state in which no impact torque is generated in the main shaft 9, and (b), (c), and (d) show states in which the liner 11 rotates approximately 90° from this state.

[0015] Impact torque is generated in the main shaft 9 when, as shown in Figures 6(b) and (d), the sealing surfaces 11a and 11b of the liner 11 and the sealing surfaces of the driving blades 14a and 14b meet, and the cavity inside the liner 11 is divided into four chambers. Due to the shape of the cavity inside the liner 11, the moment impact torque is generated in the main shaft 9, the volume of the high-pressure chamber H side decreases and the volume of the low-pressure chamber L side increases, and each chamber becomes the high-pressure chamber H and the low-pressure chamber L. That is, when the rotor 4 rotates the liner 11 and the seal surfaces 11a, 11b of the liner 11 come into alignment with the seal surfaces of the driving blades 14a, 14b, the chambers become high-pressure chamber H and low-pressure chamber L, respectively, and the driving blades 14a, 14b are pushed toward the low-pressure chamber L, causing the seal surfaces 11a, 11b of the liner 11 to come into alignment with the seal surfaces of the driving blades 14a, 14b, completely sealing the cavity inside the liner 11, and the rotational force of the liner 11 acts on the protrusions 15a, 15b of the main shaft 9 via the driving blades 14a, 14b, generating an impact torque on the main shaft 9. The impact torque generated intermittently twice per rotation of the liner 11 rotates the main shaft 9, allowing the desired operation, such as tightening or loosening of bolts and nuts, to be performed.

[0016] On the other hand, as shown in Figures 6(a) and (c), when the sealing surfaces 11a, 11b of the liner 11 and the sealing surfaces of the driving blades 14a, 14b reach a position where they meet, the respective chambers instantly become a high-pressure chamber H and a low-pressure chamber L. However, because the driving blades 14a, 14b are pushed toward the low-pressure chamber L, the sealing surfaces 11a, 11b of the liner 11 and the sealing surfaces of the driving blades 14a, 14b do not meet, and the internal cavity of the liner 11 does not become sealed, so the hydraulic oil on the high-pressure chamber H side flows through the gap between the two sealing surfaces to the low-pressure chamber L side, and therefore no impact torque is generated in the main shaft 9.

[0017] Furthermore, when the rotor 4 is rotated in the reverse direction, the interior of the liner case 7 changes as shown in Figure 6(d) → (c) → (b) → (a) → (d) ..., and an impact torque can be generated in the main shaft 9 in the opposite direction to the previous one.

[0018] Here, although the basic structure is the same as the above example, the hydraulic impact torque generating device 5 can also be configured as shown in FIGS.

[0019] In this hydraulic impact torque generating device 5, a liner 21 is provided in a liner case 7, and the liner 21 is filled with hydraulic oil and sealed.

[0020] The liner 21, into which the main shaft 9 is inserted, has a generally elliptical cavity formed therein, and four pairs of seal surfaces 21a, 21b are formed in a mountain-like shape on its inner circumferential surface. These pairs of seal surfaces, i.e., seal surfaces 21a and 21b, are positioned at 180-degree rotational symmetry. The outer periphery of the cylindrical liner 21 is supported by the liner case 7, and an upper liner lid 22 and a lower liner lid 23 are disposed on both ends of the liner 21. The liner 21, the upper liner lid 22, and the lower liner lid 23 are configured to rotate integrally by inserting knock pins (not shown) into pin holes formed in the liner 21 and pin holes 22a, 23a formed in the upper liner lid 22 and the lower liner lid 23, respectively. The upper liner lid 22 is further fixed in the axial direction by the liner case lid 7a, sealing the hydraulic oil filled inside the liner 21. Furthermore, guide grooves 22c, 23c are formed on the inner surfaces of the liner upper cover 22 and the liner lower cover 23, eccentric to the rotation axis O of the liner 21, so that the eccentric directions are rotationally symmetrical by 180 degrees. Furthermore, a pin hole 23e and a hydraulic oil injection hole 23f are formed in the liner lower cover 23. The pin hole 23e is provided with a pin that penetrates the liner case 7. By fitting the bolt 28, the liner case 7 and the liner bottom cover 23 are prevented from rotating.

[0021] Two projections 25a, 25b with smooth surfaces are formed at positions that are 180 degrees rotationally symmetrical on the main shaft 9 that is coaxially disposed inside the liner 21. The two projections 25a, 25b on the main shaft 9 are formed so that their axial and circumferential lengths are both shorter than the hollow portion inside the liner 21, thereby forming passages through which the hydraulic oil flows at both ends in the axial direction and at the ends in the circumferential direction.

[0022] Two driving blades 24a, 24b of the same size and with a smooth surface and a roughly triangular cross section are inserted into a hollow formed inside the liner 21 and partitioned by the protrusions 25a, 25b of the main shaft 9. The two driving blades 24a, 24b are formed with axial lengths that are approximately the same as the hollow inside the liner 21 so that the side surfaces of the driving blades 24a, 24b come into sliding contact with the inner surfaces of the upper liner cover 22 and the lower liner cover 23. Sealing surfaces that correspond to the sealing surfaces 21a, 21b of the liner 21 are formed near both ends of the driving blades. Pins 27a, 27b that fit into guide grooves 22c, 23c formed on the inner surfaces of the upper liner cover 22 and the lower liner cover 23 are formed on one side of the driving blades 24a, 24b. The pin 27b of the driving blade 24b is inserted into the guide groove 22c of the upper liner cover 22, and the pin 27b of the driving blade 24b is inserted into the guide groove 22c of the lower liner cover 23. The pins 27a of the driving blade 24a are inserted into the guide grooves 22c, 23c formed on the inner surfaces of the liner upper cover 22 and the liner lower cover 23 eccentrically to the rotation axis O of the liner 21, and when the sealing surfaces 21a, 21b of the liner 21 and the sealing surfaces of the driving blades 24a, 24b attempt to mate twice per rotation of the liner 21, the movement of the driving blades 24a, 24b is restricted by the pins 27a, 27b of the driving blades 24a, 24b inserted into the guide grooves 22c, 23c formed on the inner surfaces of the liner upper cover 22 and the liner lower cover 23, respectively, to prevent the mating, thereby generating an impact torque on the main shaft 9 once per rotation of the liner 21.

[0023] The outer peripheral surface of the liner 21 is provided with a communication groove 26 that interconnects the hollow portions that become the low-pressure chamber L inside the liner 21 defined by the driving blades 24a, 24b and the sealing surfaces 21a, 21b of the liner 21.

[0024] The liner 21 is also provided with an output adjustment mechanism 10 that adjusts the magnitude of the impact torque parallel to the axis of the liner 21. This output adjustment mechanism 10 is a conventionally known mechanism, and is comprised of ports 10a and 10b that communicate between a cavity that becomes a high-pressure chamber H and a cavity that becomes a low-pressure chamber L inside the liner 21, which are partitioned by the driving blades 24a and 24b and the sealing surfaces 21a and 21b of the liner 21, and an output adjustment valve 10c that is adjusted through an operation hole 23b provided in the liner bottom cover 23.

[0025] Additionally, an accumulator 29 for absorbing thermal expansion of the hydraulic oil is provided in the liner 21 parallel to the axis of the liner 21. This accumulator 29 is composed of a piston 29a and a vent member 29b, and one end face of the piston 29a is connected to the hollow inside the liner 21 via a small accumulator hole 23d drilled in the liner bottom lid 23, while the other end face is connected to the atmosphere via the vent member 29b, the small accumulator hole 22b drilled in the liner top lid 22, and the gap between the liner top lid 22 and the liner case lid 7a.

[0026] To explain the operation of the impact torque generator 5 of this hydraulic torque wrench, first, the main valve 2 and the switching valve 3 are operated to introduce high-pressure air into the rotor chamber in the main body 1, causing the rotor 4 to rotate at high speed. The rotational force of this rotor is transmitted to the liner 21.

[0027] As the liner 21 rotates, the inside of the liner case 7 flows in the order of (a) → (b) → (c) of FIG. 12(a) shows a state in which no impact torque is generated in the main shaft 9, and (b), (c), and (d) show states in which the liner 21 rotates approximately 90 degrees from this state.

[0028] An impact torque is generated in the main shaft 9 when, as shown in Figure 12(b), the sealing surfaces 21a, 21b of the liner 21 and the sealing surfaces of the driving blades 24a, 24b meet, and the cavity inside the liner 21 is divided into four chambers. Due to the shape of the cavity inside the liner 21, the moment an impact torque is generated in the main shaft 9, the volume of the high-pressure chamber H side decreases and the volume of the low-pressure chamber L side increases, and each chamber becomes the high-pressure chamber H and the low-pressure chamber L, respectively. That is, when the rotor 4 rotates the liner 21 and the seal surfaces 21a, 21b of the liner 21 come into alignment with the seal surfaces of the driving blades 24a, 24b, the chambers become high-pressure chamber H and low-pressure chamber L, respectively, and the driving blades 24a, 24b are pushed toward the low-pressure chamber L, causing the seal surfaces 21a, 21b of the liner 21 to come into alignment with the seal surfaces of the driving blades 24a, 24b, completely sealing the cavity inside the liner 21, and the rotational force of the liner 21 acts on the protrusions 25a, 25b of the main shaft 9 via the driving blades 24a, 24b, generating an impact torque on the main shaft 9. The impact torque generated intermittently once per rotation of the liner 21 rotates the main shaft 9, allowing the desired operation, such as tightening or loosening of bolts and nuts, to be performed.

[0029] On the other hand, as shown in Figure 12(d), the sealing surfaces 21a, 21b of the liner 21 and the sealing surfaces of the driving blades 24a, 24b attempt to mate, but at this time the movement of the driving blades 24a, 24b is restricted by the pins 27a, 27b of the driving blades 24a, 24b inserted into the guide grooves 22c, 23c formed eccentrically with the rotation axis O of the liner 21 on the inner surfaces of the liner upper cover 22 and the liner lower cover 23. As a result, the hollow portion inside the liner 21 is not sealed, and no impact torque is generated in the main shaft 9.

[0030] 12(a) and 12(c), when the sealing surfaces 21a, 21b of the liner 21 and the sealing surfaces of the driving blades 24a, 24b reach a position where they meet, the respective chambers instantaneously become a high-pressure chamber H and a low-pressure chamber L, but because the driving blades 24a, 24b are pushed toward the low-pressure chamber L, the sealing surfaces 21a, 21b of the liner 21 and the sealing surfaces of the driving blades 24a, 24b do not meet, and the internal cavity of the liner 21 does not become sealed, so the hydraulic oil on the high-pressure chamber H side flows through the gap between the two sealing surfaces to the low-pressure chamber L side, and therefore no impact torque is generated in the main shaft 9.

[0031] Furthermore, when the rotor 4 is rotated in the reverse direction, the interior of the liner case 7 changes as shown in Figure 12(d) → (c) → (b) → (a) → (d) ..., and an impact torque can be generated in the main shaft 9 in the opposite direction to the previous one.

[0032] The hydraulic impact torque generator 5 shown in Figures 1 to 6 and Figures 7 to 12 does not require the blades that are constantly biased toward the outer periphery of the spindle by a spring, which was essential in the impact torque generator of the conventional hydraulic torque wrench shown in Figure 19, and has the advantages of being able to provide an impact torque generator for a hydraulic torque wrench that has low sliding resistance, good energy efficiency, little temperature rise in the hydraulic oil, stable output, is small, has a simple structure, and is durable.

[0033] The present invention aims to provide an impact torque generator for a hydraulic torque wrench that is a further improvement on the hydraulic impact torque generator 5 shown in Figures 1 to 6 and 7 to 12, and that has a simpler structure, is more durable, has less sliding resistance, and is more energy efficient. [Means for solving the problem]

[0034] In order to achieve the above object, the impact torque generating device of the hydraulic torque wrench of the present invention comprises: a liner that is rotated by the rotor and has a cavity filled with hydraulic oil and a seal surface that protrudes from the inner circumferential surface of the cavity; a main shaft having two protrusions and coaxially disposed inside the liner; and two driving blades having sealing surfaces at both ends and inserted into a cavity of the liner filled with hydraulic oil, In a hydraulic torque wrench impact torque generating device, the inside of the liner is divided into a high-pressure chamber and a low-pressure chamber by a driving blade, and impact torque is generated in the main shaft. The two sealing surfaces of the liner are formed at positions 180° apart in the cavity, and The cross-sectional shapes of the two protrusions on the main shaft are asymmetrical across the minor axis, When the seal surface of the liner and one of the seal surfaces of each driving blade are aligned, the other seal surface slides against the inner surface of the hollow portion to form a seal. This allows the driving blade to divide the inside of the liner into a high-pressure chamber and a low-pressure chamber, generating one impact torque on the main shaft per rotation of the liner.

[0035] In this case, a guide groove for restricting the movement of the driving blade can be provided on the inner surface of either the upper liner cover or the lower liner cover of the liner. [Effects of the Invention]

[0036] According to the impact torque generating device of the hydraulic torque wrench of the present invention, the two sealing surfaces of the liner are formed at positions asymmetrical with respect to 180° rotation of the hollow portion, and the cross-sectional shapes of the two protrusions of the main shaft are formed asymmetrical with respect to the minor axis. This allows one impact torque to be generated in the main shaft per rotation of the liner, in both forward and reverse rotation, making it possible to generate a large impact torque with a small device.

[0037] In this case, a guide groove for regulating the movement of the driving blade can be provided on the inner surface of either the upper liner lid or the lower liner lid of the liner, simplifying the structure. In particular, if a guide groove for regulating the movement of the driving blade is provided only on the inner surface of the upper liner lid of the liner, the guide groove on the lower liner lid becomes unnecessary, the shaft diameter of the main shaft can be increased, and durability can be improved. [Brief explanation of the drawings]

[0038] [Figure 1] An example of an impact torque generating device for a hydraulic torque wrench is shown, where (a) is a front cross-sectional view and (b) is a cross-sectional view taken along line II. [Figure 2] FIG. 2 is a diagram showing a driving blade of the impact torque generating device of the same example. [Figure 3] FIG. 2 is a diagram showing a main shaft of the impact torque generating device of the same example. [Figure 4] FIG. 2 is a view showing a liner upper cover of the impact torque generating device of the same example. [Figure 5] FIG. 2 is a view showing a liner lower cover of the impact torque generating device of the same example. [Figure 6] 4A to 4C are diagrams illustrating the operation of the impact torque generating device of the same example. [Figure 7] 1 shows another example of an impact torque generating device for a hydraulic torque wrench, where (a) is a front cross-sectional view and (b) is a cross-sectional view taken along line II-II. [Figure 8] FIG. 2 is a diagram showing a driving blade of the impact torque generating device of the same example. [Figure 9] FIG. 2 is a diagram showing a main shaft of the impact torque generating device of the same example. [Figure 10] FIG. 2 is a view showing a liner upper cover of the impact torque generating device of the same example. [Figure 11] FIG. 2 is a view showing a liner lower cover of the impact torque generating device of the same example. [Figure 12] 4A to 4C are diagrams illustrating the operation of the impact torque generating device of the same example. [Figure 13]1A and 1B show an embodiment of an impact torque generating device for a hydraulic torque wrench according to the present invention, in which FIG. 1A shows a liner, and FIG. 1B shows a liner lower cover. [Figure 14] 1A and 1B show the main shaft of the impact torque generating device of the same embodiment, where (a) is a front view, (b) is a cross-sectional view of the protrusion as seen from the tip end of the main shaft, and (c) is a cross-sectional view of the protrusion as seen from the tip end of the main shaft (comparative example). [Figure 15] 4A and 4B are diagrams illustrating the operation of the impact torque generating device of the embodiment during forward rotation. [Figure 16] FIG. 4 is an enlarged view showing the operation of the impact torque generating device of the embodiment during forward rotation. [Figure 17] 10A and 10B are diagrams illustrating the operation of the impact torque generating device of the embodiment during reverse rotation. [Figure 18] FIG. 4 is an enlarged view showing the operation of the impact torque generating device of the embodiment during reverse rotation. [Figure 19] 1 is a diagram showing the entire hydraulic impact wrench incorporating a conventional impact torque generating device. DETAILED DESCRIPTION OF THE INVENTION

[0039] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an impact torque generating device for a hydraulic torque wrench according to the present invention will now be described with reference to the accompanying drawings.

[0040] 13 to 18 show an embodiment of an impact torque generating device for a hydraulic torque wrench according to the present invention.

[0041] This hydraulic impact torque generator 5 is a further improvement of the hydraulic impact torque generator 5 shown in Figures 1 to 6 and 7 to 12, and has a simpler structure, is more durable, has less sliding resistance, and is more energy efficient.

[0042] The basic structure is the same as that of the hydraulic impact torque generating device 5 shown in Figures 1 to 6 and 7 to 12, with a liner 31 provided inside the liner case 7, which is filled with hydraulic oil and sealed, and the main shaft 9 being inserted coaxially into the liner 31.

[0043] A liner 31 into which the main shaft 9 is fitted is formed with a substantially elliptical cavity therein, and two mountain-shaped seal surfaces 31a, 31b are formed on the inner circumferential surface thereof at positions asymmetrical with respect to 180° rotation. Specifically, the seal surface 31b is formed at a position shifted by θ1 (5 to 10°, approximately 7° in this embodiment) from a position rotationally symmetrical by 180° to the seal surface 31a. The outer periphery of this cylindrical liner 31 is supported by the liner case 7, and an upper liner lid 32 and a lower liner lid 33 are disposed on both ends of the liner 31. The liner 31, upper liner lid 32, and lower liner lid 33 are configured to rotate integrally by inserting knock pins (not shown) into pin holes provided in the liner 31 and pin holes provided respectively in the upper liner lid 32 and lower liner lid 33. The upper liner lid 32 is further fixed in the axial direction by the liner case lid 7a, so as to seal the hydraulic oil filled inside the liner 31. Further, guide grooves 32c, 33c concentric with the rotation axis O of the liner 31 are formed on the inner surface of the liner upper cover 32 or the liner lower cover 33. The guide grooves 32c, 33c may be provided on the inner surface of either the liner upper lid 32 or the liner lower lid 33. In particular, by providing the guide groove 32c only on the inner surface of the liner upper lid 32, the guide groove 33c of the liner lower lid 33 is unnecessary, the shaft diameter of the main shaft 9 can be increased, and, combined with the fact that the guide groove 32c is concentric with the rotation axis O of the liner 31, the structure can be simplified and durability can be improved. Furthermore, grooves for releasing hydraulic oil are formed at predetermined positions on the inner surfaces of the liner upper cover 32 and the liner lower cover 33.

[0044] Here, the hydraulic impact torque generator 5 of this embodiment differs from the hydraulic impact torque generator 5 shown in FIGS. 1 to 6 and 7 to 12 in that the other seal surfaces 31a' and 31b' of the pair of seal surfaces 31a and 31b, i.e., the seal surfaces of the liner 31 corresponding to the seal surfaces of the driving blades 34a and 34b described later, are configured by the inner circumferential surface of the cavity. It is set to. The inner peripheral surface of the hollow portion of the liner 31 that forms the sealing surfaces 31a' and 31b' has an approximately cylindrical shape, with an angle θ2 of 30° to 70°, preferably 40° to 60° (50° in this embodiment). As a result, by providing two mountain-shaped seal surfaces 31a, 31b, it is possible to substantially omit the process of machining the hollow portion of the liner 31 that forms these seal surfaces 31a', 31b', thereby providing an impact torque generating device for a hydraulic torque wrench that has a simple structure and is durable.

[0045] The main shaft 9, which is coaxially disposed inside the liner 31, is formed with two protrusions 35a, 35b such that the cross-sectional shapes thereof are asymmetrical across the minor axis. Specifically, as shown in Figure 14(b), the two protrusions 35a and 35b each have an approximately triangular shape, with one protrusion 35a having two equal base angles α (75° in this embodiment), and the other protrusion 35b having two different base angles α1 and α2 (α1: 68°, α2: 82° in this embodiment). In this way, by forming the cross-sectional shapes of the two protrusions 35a, 35b of the main shaft 9 asymmetrically on either side of the short axis, coupled with the fact that the two sealing surfaces 31a, 31b of the liner 31 are formed in positions asymmetrical at 180° rotation, it is possible to generate one impact torque in the main shaft per rotation of the liner, in both forward and reverse rotation. The two protrusions 35a, 35b of the main shaft 9 are formed so that their axial and circumferential lengths are both shorter than the hollow portion inside the liner 31, thereby forming passages through which the hydraulic oil flows at both ends in the axial direction and at the tip in the circumferential direction.

[0046] Two driving blades 34a, 34b of the same size and with a smooth surface and a roughly triangular cross section are inserted into a hollow formed inside liner 31 and partitioned by protrusions 35a, 35b of main shaft 9. The two driving blades 34a, 34b are formed with axial lengths that are approximately the same as the hollow inside liner 31 so that the side surfaces of driving blades 34a, 34b come into sliding contact with the inner surfaces of liner upper cover 32 and liner lower cover 33, and seal surfaces corresponding to seal surfaces 31a, 31a', 31b, 31b' of liner 31 are formed near both ends. Steel balls 37a, 37b are arranged on one side of the driving blades 34a, 34b and fitted into guide grooves 32c, 33c formed on the inner surface of either the liner upper lid 32 or the liner lower lid 33, and are fitted into the guide groove 32c of the liner upper lid 32 (or the guide groove 33c of the liner lower lid 33) to regulate the movement of the driving blades 34a, 34b.

[0047] Here, instead of the steel balls 37a, 37b used in this embodiment that are inserted into guide groove 32c (or guide groove 33c) to guide and regulate the movement of driving blades 34a, 34b, it is also possible to apply pins 27a, 27b that are inserted into guide grooves 22c, 23c used in hydraulic impact torque generator 5 shown in Figures 7 to 12 to guide and regulate the movement of driving blades 34a, 34b.

[0048] The outer peripheral surface of the liner 31 is provided with a communicating groove (not shown) that interconnects the hollow portions that form the low-pressure chamber L inside the liner 31, which are partitioned by the driving blades 34a, 34b and the sealing surfaces 31a, 31a', 31b, 31b' of the liner 31.

[0049] The liner 31 is provided with an output adjustment mechanism 10 for adjusting the magnitude of the impact torque parallel to the axis of the liner 31. This output adjustment mechanism 10 is a conventionally known mechanism, and is configured to adjust the magnitude of the impact torque parallel to the axis of the liner 31. The output adjustment mechanism 10 is configured to adjust the magnitude of the impact torque parallel to the axis of the liner 31. The output adjustment mechanism 10 is configured to adjust the magnitude of the impact torque parallel to the axis of the liner 31. The output adjustment mechanism 10 is configured to adjust the magnitude of the impact torque parallel to the axis of the liner 31. and an output adjustment valve 10c that is adjustably screwed into a screw hole provided in the liner lower cover 33.

[0050] The liner 31 is provided with an accumulator 39 parallel to the axis of the liner 31 for absorbing thermal expansion of the hydraulic oil.

[0051] To explain the operation of the impact torque generator 5 of this hydraulic torque wrench, first, the main valve 2 and the switching valve 3 are operated to introduce high-pressure air into the rotor chamber in the main body 1, causing the rotor 4 to rotate at high speed. The rotational force of this rotor is transmitted to the liner 31.

[0052] As the liner 31 rotates, the interior of the liner case 7 changes as shown in FIG. 15(a)→(a')→(b)→(c)→(c')→(d)→(a)→···.

[0053] An impact torque is generated in the main shaft 9 when, as shown in Figure 15(c) (Figure 16(c)), the sealing surfaces 31a, 31a', 31b, 31b' of the liner 31 mate with the sealing surfaces of the driving blades 34a, 34b, and the cavity inside the liner 31 is divided into four chambers. Due to the shape of the cavity inside the liner 31, the moment an impact torque is generated in the main shaft 9, the volume on the high-pressure chamber H side decreases and the volume on the low-pressure chamber L side increases, and each chamber becomes the high-pressure chamber H and the low-pressure chamber L, respectively. That is, when liner 31 is rotated by rotor 4 and reaches a position where sealing surfaces 31a, 31a', 31b, and 31b' of liner 31 align with the sealing surfaces of driving blades 34a and 34b, the respective chambers become high-pressure chamber H and low-pressure chamber L, and driving blades 34a and 34b are pushed toward low-pressure chamber L, causing sealing surfaces 31a, 31a', 31b, and 31b' of liner 31 to align with the sealing surfaces of driving blades 34a and 34b, completely sealing the internal cavity of liner 31. The rotational force of liner 31 acts on protrusions 35a and 35b of main shaft 9 via driving blades 34a and 34b, generating an impact torque on main shaft 9. The impact torque generated intermittently once per rotation of liner 31 rotates main shaft 9, thereby performing the desired operation, such as tightening or loosening bolts and nuts.

[0054] On the other hand, in any state other than Figure 15(c) (Figure 16(c)), the sealing surfaces 31a, 31a', 31b, 31b' of the liner 31 do not match the sealing surfaces of the driving blades 34a, 34b, and the hollow portion inside the liner 31 is not sealed, so no impact torque is generated in the main shaft 9.

[0055] Furthermore, when the rotor 4 is rotated in the reverse direction, the rotation of the liner 31 causes the interior of the liner case 7 to change as shown in Figure 17(a) → (a') → (b) → (c) → (c') → (d) → (a) → ...

[0056] An impact torque is generated in the main shaft 9 when shown in Figure 17(c) (Figure 18(c)), and an impact torque in the opposite direction can be generated in the main shaft 9, while no impact torque is generated in the main shaft 9 when not shown in Figure 17(c) (Figure 18(c)).

[0057] Other configurations and operations of this hydraulic impact torque generating device 5 are the same as those of the hydraulic impact torque generating device 5 shown in FIGS. 1 to 6 and 7 to 12.

[0058] The impact torque generating device for a hydraulic torque wrench of the present invention has been described above based on its embodiments, but the present invention is not limited to the configuration described in the above embodiments. For example, the configuration can be changed as appropriate within the scope of the invention, such as using an electric motor instead of an air motor as the driving motor. [Industrial Applicability]

[0059] The impact torque generating device for the hydraulic torque wrench of the present invention does not require blades that are constantly biased toward the outer periphery of the spindle by a spring, has low sliding resistance and good energy efficiency, produces stable output with little temperature rise of the hydraulic oil, is small in size, has a simple structure, and is durable. Therefore, it can be suitably used for hydraulic torque wrenches that use electric motors that cannot expect the air-cooling effect of high-pressure air as a power source, and hydraulic torque wrenches that require high tightening accuracy, and can also be used for hydraulic torque wrenches that use air motors, for example. [Explanation of symbols]

[0060] 1 Main unit 2 Main Valve 3 Forward / reverse rotation switching valve 4 rotors 5. Impact torque generator 6 Front case 7 Liner Case 8 Liner 9 Main axis 10 Output adjustment mechanism 11 Liner 11a Sealing surface of liner 11b Sealing surface of liner 12 Liner top cover 13 Liner bottom cover 14a driving blade 14b Driving Blade 15a Protrusion of the main shaft 15b Protrusion of the main shaft 16 Communication groove 17 Knock pin 21 Liner 21a Sealing surface of liner 21b Sealing surface of liner 22 Liner top cover 22c Guide groove 23 Liner bottom cover 23c Guide groove 24a driving blade 24b driving blade 25a Protrusion of the main shaft 25b Protrusion of the main shaft 26 Communication groove 27a pin 27b pin 29 Accumulator 31 Liner 31a Sealing surface of liner 31a' Sealing surface of liner 31b Sealing surface of liner 31b' Sealing surface of liner 32 Liner top cover 32c Guide groove 33 Liner bottom cover 33c Guide groove 34a driving blade 34b Driving Blade 35a Protrusion of the main shaft 35b Protrusion of the main shaft 37a steel ball 37b steel ball 39 Accumulator H Hyperbaric chamber L Low pressure chamber S spring

Claims

1. a liner that is rotated by the rotor and has a cavity filled with hydraulic oil and a seal surface that protrudes from the inner circumferential surface of the cavity; a main shaft having two protrusions and coaxially disposed inside the liner; two driving blades having sealing surfaces at both ends and inserted into a cavity of the liner filled with hydraulic oil; In a hydraulic torque wrench impact torque generating device, the inside of the liner is divided into a high-pressure chamber and a low-pressure chamber by a driving blade, and impact torque is generated in the main shaft. The two sealing surfaces of the liner are formed at positions asymmetrical with respect to 180° rotation of the cavity, The cross-sectional shapes of the two protrusions of the main shaft are asymmetrical across the minor axis, An impact torque generating device for a hydraulic torque wrench, characterized in that when the sealing surface of the liner and one of the sealing surfaces of each driving blade are aligned, the other sealing surface slides against the inner surface of the hollow portion to form a seal, thereby dividing the inside of the liner into a high-pressure chamber and a low-pressure chamber by the driving blade, and generating one impact torque on the main shaft per rotation of the liner.

2. 2. The impact torque generating device for a hydraulic torque wrench according to claim 1, wherein a guide groove for regulating the movement of the driving blade is provided on the inner surface of either the upper liner cover or the lower liner cover of the liner.

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