Power tool comprising a hydraulic impulse unit

Abstract

The present specification relates to an impact tool comprising a hydraulic impulse unit arranged to intermittently deliver torque impulses to a tool output shaft, the impact tool comprising an inertia drive member comprising a hydraulic fluid chamber and being intermittently coupled to the output shaft via a hydraulic impulse generating device dividing the hydraulic fluid chamber into a low pressure chamber and a high pressure chamber. A bypass channel is provided to fluidly communicate between the high pressure chamber and the low pressure chamber, wherein the hydraulic impulse generating mechanism further comprises a first check valve arranged to allow a first flow from the low pressure side to the high pressure side and a second check valve arranged to allow a second flow from the low pressure side to the high pressure side. The present specification also relates to a combined valve unit and bushing for use in an impulse unit of an impulse tool.

Description

Technical Field

[0001] The present invention generally relates to power tools for tightening threaded fasteners, and more specifically, to impact power tools having a hydraulic pulse unit. Background Technology

[0002] Power tools used for tightening are known to be used in a variety of industries. For example, pulse power wrenches, which include hydraulic pulse units, are commonly used in continuous, large-scale production.

[0003] The hydraulic unit of this tool is filled with oil. In this pulse tool, torque pulses can be transmitted to the output shaft via a pulse generating mechanism that divides the fluid chamber into a low-pressure side and a high-pressure side, allowing fluid to flow between the two sides during operation.

[0004] However, such fluid flow is usually associated with losses, and therefore has a significant impact on the efficiency of pulse tools.

[0005] To mitigate these issues, several solutions have been proposed, including the design and combination of various fluid paths and / or valves configured to allow fluid to flow between low-pressure and high-pressure sides. However, pulse tools with such designs suffer from known problems, including increased complexity and reduced durability.

[0006] Therefore, there is a need for improvement in the field of power tools, including those with hydraulic pulse units. Summary of the Invention

[0007] Therefore, it is desirable to provide a pulse tool that keeps losses due to flow limitations low. In particular, it is desirable to provide such an improved pulse tool in a less complex and more durable manner. To better address one or more of these problems, pulse tools and valve units according to the independent claims are provided. Preferred embodiments are defined in the dependent claims.

[0008] According to a first aspect of the invention, a pulse tool is provided, comprising: a motor; an output shaft; and a hydraulic pulse unit coupled to the motor and arranged to intermittently transmit torque pulses to the output shaft. The hydraulic pulse unit includes an inertial drive member connected to the motor, wherein the drive member includes a hydraulic fluid chamber; wherein an impact receiving portion of the output shaft extends coaxially into the hydraulic fluid chamber, and an impact receiving output portion is intermittently coupled to the drive member via a hydraulic pulse generating mechanism dividing the hydraulic fluid chamber into at least one low-pressure chamber and at least one high-pressure chamber; wherein a bypass passage is provided to allow fluid communication between the high-pressure chamber and the low-pressure chamber; and wherein the hydraulic pulse generating mechanism further includes: a first check valve arranged to allow a first flow from the low-pressure side to the high-pressure side, and a second check valve arranged to allow a second flow from the low-pressure side to the high-pressure side.

[0009] According to the first aspect, the impact tool (or pulse tool, power wrench, power tool or tightening tool, these terms are used interchangeably in this specification) provides an ingenious solution to the above problem by incorporating a fluid path design that ensures the required flow between the low-pressure side and the high-pressure side.

[0010] More specifically, the design with two check valves allows for greater flow from the low-pressure side to the high-pressure side, thereby reducing losses in the pulse unit. As a result, the performance of the power tool can be significantly improved.

[0011] The pulse tool mentioned can be an electric pulse tool or a pneumatic pulse tool. The pulse tool may further include a housing with a front end and a rear end, wherein an output shaft may be arranged at the front end of the housing. Furthermore, the high-pressure chamber and low-pressure chamber may also be referred to as a high-pressure chamber and a low-pressure chamber, a high-pressure side and a low-pressure side, or a high-pressure area and a low-pressure area.

[0012] The first and second check valves can be arranged in a manner that facilitates sufficient flow from the low-pressure side. For example, in one embodiment, the valves can be arranged on opposite sides of the chamber, i.e., at an angular distance of 180 degrees.

[0013] In one embodiment, the impact receiving portion may be integral with the output shaft and extend into the fluid chamber via a central opening in the front wall of the inertial drive member. Furthermore, the output member may include a transverse cylinder bore in which a movably guided piston is arranged. The piston may reciprocate within the cylinder bore via a cam comprising two cam lobes formed on the inner wall of the fluid chamber, acting on the piston via, for example, rollers to drive the piston inward, thereby generating a pressure peak. A central camshaft may be rotatably supported in the output member to allow the piston and rollers to return to their external positions.

[0014] According to one embodiment, the bypass channel is separately located from the first and second flows. For example, the bypass channel or leakage flow may be located separately from the first and second check valves. In some embodiments, the leakage flow is provided by a separate component.

[0015] According to one embodiment, the bypass passage and at least a portion of one of the first and second check valves are formed as a single component. For example, the first and / or second valves may be valve units, and the bypass passage may be formed in one of these units (or extend through one of these units). Therefore, sufficient flow can be ensured in a particularly compact manner.

[0016] According to one embodiment, a single component includes a body, wherein a central orifice is disposed in the body to allow the flow of hydraulic fluid, wherein a valve body is arranged to selectively close the central orifice, and wherein a bypass passage is configured to provide fluid communication between a high-pressure chamber and a low-pressure chamber through the single component.

[0017] In one implementation, the body has a cylindrical shape.

[0018] According to one embodiment, at least one bypass channel extends axially through the body. For example, the bypass channel may extend along the axis of the cylindrical body.

[0019] In one implementation, the flow through the bypass channel can be substantially parallel to the flow through the check valve.

[0020] According to one embodiment, the bypass channel is arranged radially outside the central aperture. Radial refers to the radius of the central aperture.

[0021] According to one embodiment, at least two bypass channels are arranged equidistantly along the circumference C1 of the central hole. "Along" should be understood as along a portion of the body adjacent to the circumference C1.

[0022] According to one embodiment, at least one central hole forms part of a conical valve seat, and wherein the at least one bypass passage is arranged along a portion of the conical valve seat adjacent to the outer circumference C2 of the conical valve seat. That is, along a portion of the body adjacent to the circumference C2.

[0023] According to one embodiment, the bypass channel is formed by at least one leakage orifice for allowing leakage flow through the individual component. The leakage orifice should be understood as a small orifice that allows a small flow rate from the high-pressure side to the low-pressure side during a pulse.

[0024] According to one implementation, a single component is a combined bushing and valve unit with a cylindrical shape.

[0025] According to one embodiment, the body is a cylindrical bushing body having a central bore for allowing the flow of hydraulic fluid, wherein at least one leakage bore is a bore for allowing leakage flow through the bushing body forming a bypass passage. In one embodiment, the body can therefore be described as a combined valve unit and leakage bore bushing comprising a check valve assembly and one or more leakage bores.

[0026] According to one embodiment, the components are detachably arranged within the pulse unit. This is advantageous because it allows for modularity and facilitates unit maintenance / replacement.

[0027] Such bushings may further include means for engaging screwdrivers or the like to facilitate assembly and / or repair and replacement. Such means may be adapted to engage any tool tip shape, such as Torx, hexagonal, etc.

[0028] According to one embodiment, a bypass channel is disposed in a separate element having a central aperture for allowing leakage flow through the element, the central aperture forming part of the bypass channel. The element may include a body, such as a cylindrical bushing body in which the central aperture is formed. In one embodiment, the separate element has substantially the same dimensions as the first valve unit and the second valve unit.

[0029] According to one embodiment, the first check valve and the second check valve are ball check valves comprising a corresponding ball and a seat. The seat may be formed in the valve body, forming a valve unit together with the ball. The first check valve and / or the second check valve may be formed in a first valve unit and a second valve unit that can be detachably arranged in the pulse unit.

[0030] According to another aspect of the invention, a combined valve unit and bushing for a pulse tool is provided, the combined valve unit and bushing comprising a body having a central bore therein to allow flow of hydraulic fluid, a sphere arranged to selectively close the central bore / fluid flow, and at least one leakage orifice for allowing leakage flow through a single component to form a bypass passage. From the above discussion with reference to the first aspect of the invention, the objectives, advantages, and features of the valve unit conceivable within the scope of the second aspect of the invention can be readily understood.

[0031] Further objects, features, and advantages of the invention will become apparent upon studying the following detailed disclosure, drawings, and appended claims. Those skilled in the art will understand that different features of the invention can be combined to create embodiments other than those described below. Attached Figure Description

[0032] The invention will be described in an illustrative and non-limiting detailed description of the following exemplary embodiments with reference to the accompanying drawings, in which...

[0033] Figure 1 This is a three-dimensional view of an exemplary pulse tool.

[0034] Figure 2a This is a cross-sectional view of an exemplary pulse unit of a power tool according to one embodiment.

[0035] Figure 2b This is a cross-sectional view of an exemplary pulse unit of a power tool according to another embodiment.

[0036] Figure 3aThis is a cross-sectional view of an exemplary pulse unit according to one embodiment.

[0037] Figure 3b This is a cross-sectional view of an exemplary pulse unit according to one embodiment.

[0038] Figure 4a and Figure 4b These are different perspective views of the combined bushing and valve unit according to an exemplary embodiment.

[0039] All accompanying drawings are schematic and not necessarily drawn to scale, and generally only show the parts necessary to illustrate the invention, wherein other parts may be omitted or only suggested. Detailed Implementation

[0040] Figure 1 An exemplary pulse tool 1 according to one embodiment is shown, in which the pistol-type tool includes a housing 100 having a front end 100a and a rear end 100b, in which a motor and a hydraulic pulse unit are arranged, and the housing 100 further has an output shaft 10 extending at a square end at the front end of the housing.

[0041] Figure 2 illustrates an exemplary hydraulic pulse unit 20 according to one embodiment. The pulse unit or impact unit is adapted to be coupled to a motor and arranged to intermittently transmit torque pulses to the output shaft.

[0042] The hydraulic pulse unit includes an inertial drive component comprising a cylindrical front part 25 and an end part 24. The rear part 24 or end part 24 has a connecting portion for connection to a motor. The inertial drive component further includes a hydraulic fluid chamber, in this case an oil chamber, surrounded by the front and end parts, into which an impact receiving portion 11 of the output shaft extends. In the illustrated embodiment, the impact receiving portion is integral with the output shaft 10 and extends into the fluid chamber via a central opening in the front end wall of the inertial drive component.

[0043] During use, the impact receiving output section is intermittently connected to the drive component via a hydraulic pulse generating mechanism 30, which divides the hydraulic fluid chamber into at least one low-pressure chamber 31 and at least one high-pressure chamber 32 (e.g., Figure 2b (As shown in the cross-sectional view).

[0044] To achieve the pressure pulse, the output shaft in this embodiment includes a transverse cylinder bore in which a movably guided piston is arranged. The piston reciprocates within the cylinder bore via a cam, which includes two cam lobes formed on the inner wall of a fluid chamber, acting on the piston via rollers to drive the piston inward, thereby generating a pressure peak. However, the operation of the impact mechanism itself is known in the art and will not be described in further detail; similar mechanisms have previously been described, for example, in U.S. Patent 6,110,045 and U.S. Patent 13,697,107.

[0045] Several fluid flows are provided to allow fluid communication between the high-pressure chamber and the low-pressure chamber. Figure 3a and Figure 3b Two exemplary embodiments illustrating these fluid flows are shown. For example, a bypass passage 40 is provided to allow flow between chambers, and the hydraulic pulse generating mechanism further includes a first check valve 51 and a second check valve 52, the first check valve 51 being arranged to allow a first flow from the low-pressure side to the high-pressure side, and the second check valve 52 being arranged to allow a second flow from the low-pressure side to the high-pressure side. Both valves or valve units have a cylindrical shape and are detachably arranged within the pulse unit.

[0046] During operation of the impact unit, the inertial drive component rotates via a motor, and a torque impact is achieved in the output shaft 10, as described above, by the reciprocating motion of a piston via a cam, resulting in increased pressure. As the pressure increases, oil flows from the high-pressure side to the low-pressure side via the aforementioned bypass channel 40, allowing the piston to move inward and thus causing the cam to pass over the rollers, thereby allowing acceleration of the shaft. To return the piston and rollers to their external positions, a central camshaft is rotatably supported in the output component (not shown). When the central camshaft rotates to return the piston and rollers, oil is drawn back into the high-pressure chamber via the first check valve 51 and the second check valve 52, thereby allowing a high oil backflow rate.

[0047] exist Figure 3a In the illustrated embodiment, the bypass channel 40 is separated from the first and second flows via a first valve 51 and a second valve 52. More specifically, the bypass channel 40 is disposed in a separate cylindrical bushing body 60 having a central aperture 61 for allowing bypass or leakage flow through the bushing body, thereby forming the bypass channel.

[0048] The first check valve 51 and the second check valve 52 are ball check valves. Each check valve includes a valve body 54, and a valve seat 55 is arranged inside the valve body 54 to interact with the corresponding ball 56. Figure 3a As shown, the individual cylindrical bushing body 60 in the illustrated embodiment has substantially the same dimensions as the first valve body 51 and the second valve body 52.

[0049] exist Figure 3b Another embodiment of the pulse unit is shown. In this embodiment, the bypass channel 40 and, in this case, the second check valve 52 are formed as a single component 70. In the illustrated embodiment, it is in the form of a combined bushing and valve unit or a leak hole bushing unit, having a cylindrical shape and being detachably arranged within the pulse unit.

[0050] Figures 4a to 4b The bushing unit shown in detail includes a bushing body having a central bore 72 to allow the flow of hydraulic fluid and forming part of a conical valve seat 73 that interacts with the ball. In this case, a bypass passage is formed by three leakage holes 41, 42, and 43, which are equidistantly arranged along or relative to the circumference C1 of the central bore (i.e., along the portion of the conical valve seat 73 adjacent to the outer circumference C2 of the conical valve seat, and thus located radially outside the central bore 72).

[0051] Therefore, the bypass or leakage flow and the first-order fluid path are all located in the same bushing body to enable fluid communication between the high-pressure chamber and the low-pressure chamber through a single component.

[0052] Figure 4b A device 74 for engaging a screwdriver or similar object is shown, provided in the bushing body, in which case the device is adapted to engage a Torx screwdriver.

[0053] Similar to the above implementation scheme, the first check valve 51 is also a ball check valve including a ball and a valve seat.

[0054] Although the invention has been shown and described in detail in the accompanying drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or exemplary, not restrictive; the invention is not limited to the disclosed embodiments. Those skilled in the art will understand that many changes, modifications, and substitutions will occur within the scope defined in the appended claims. Furthermore, those skilled in the art will understand and implement various modifications to the disclosed embodiments upon practice of the claimed invention, study of the drawings, disclosure, and appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude multiple. The fact that certain measures are stated in mutually different dependent claims does not mean that a combination of these measures cannot be used advantageously. Any reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

1. A pulse tool, comprising: motor, Output shaft (10); as well as A hydraulic pulse unit (20), which is connected to the motor and arranged to intermittently transmit torque pulses to the output shaft, The hydraulic pulse unit includes an inertial drive component connected to the motor. The inertial drive component includes a hydraulic fluid chamber; The impact receiving portion (11) of the output shaft extends coaxially into the hydraulic fluid chamber. The impact receiving portion is intermittently connected to the inertial drive member via a hydraulic pulse generating mechanism (30). The hydraulic pulse generating mechanism (30) divides the hydraulic fluid chamber into at least one low-pressure chamber (31) and at least one high-pressure chamber (32). A bypass channel (40) is provided to allow fluid communication between the high-pressure chamber and the low-pressure chamber, and The hydraulic pulse generating mechanism further includes: A first check valve (51) is arranged to allow a first flow from the low-pressure side to the high-pressure side, and A second check valve (52) is arranged to allow a second flow from the low-pressure side to the high-pressure side.

2. The pulse tool according to claim 1, wherein, The bypass channel is separately configured from the first flow and the second flow.

3. The pulse tool according to claim 1, wherein, The bypass channel and at least a portion of one of the first check valve and the second check valve are formed as a single component (70).

4. The pulse tool according to claim 3, wherein, The single component includes a cylindrical body, wherein a central hole (72) is axially disposed in the body to allow the flow of hydraulic fluid, wherein a valve body (54) is arranged to selectively close the central hole, and wherein the bypass passage is configured to provide fluid communication between a high-pressure chamber and a low-pressure chamber through the single component.

5. The pulse tool according to claim 2, wherein, The bypass channel is disposed in the cylindrical body (60) and extends axially through the body.

6. The pulse tool according to claim 4, wherein, The bypass channel is arranged radially outside the central hole.

7. The pulse tool according to claim 4 or 6, comprising at least two bypass channels equidistantly arranged along the circumference (C1) of the central hole.

8. The pulse tool according to claim 4 or 6, wherein, The central hole forms part of a conical valve seat (73), and at least one bypass passage is arranged along a portion of the conical valve seat adjacent to the outer circumference (C2) of the conical valve seat.

9. The pulse tool according to claim 3, wherein, The bypass channel is formed by at least one leakage hole (41; 42; 43) for allowing leakage flow through the individual component.

10. The pulse tool according to claim 3, wherein, The individual component is a combined bushing and valve unit with a cylindrical shape.

11. The pulse tool according to claim 10, wherein, The bypass channel is formed by at least one leakage hole (41; 42; 43) for allowing leakage flow through the single component, the single component including a cylindrical bushing body having a central hole for allowing hydraulic fluid flow, and wherein the at least one leakage hole is a hole for allowing leakage flow through the bushing body forming the bypass channel.

12. The pulse tool according to claim 3, wherein, The individual components are detachably arranged in the hydraulic pulse unit.

13. The pulse tool according to claim 2, wherein, The bypass channel is disposed in a separate element having a central hole for allowing leakage flow through the element, the central hole forming part of the bypass channel.

14. The pulse tool according to claim 1, wherein, The first check valve and the second check valve are ball check valves, each including a ball and a seat.

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