WO2010134296A1 - Impact tool - Google Patents

Abstract

Disclosed is an impact tool which is a power tool that is designed to be connected to the ground under a given condition and provides a rotational motion with an angular speed and/or torque which changes periodically. The impact tool is configured such that when gears (1, 2, 3, 4) respectively have pitch circle radii r₁(Θ), r₂(Θ), r₃(Θ) and r₄(Θ), Θ represents the angular position of a planet shaft (7) which connects the gear (2) and the gear (3), and the radii of the gears (1, 2, 3, 4) fall within the angular range of at least 0≤Θ≤2π, a drive train is configured so as to satisfy the following inequality: r₁(Θ)·r₃(Θ)/ r₂(Θ)·r₄(Θ)>1, and thereby the direction of the rotation of an output shaft is reversed during at least some part of a drive cycle. The impact tool which resolves conventional problems including high noise, high vibration, high loss, and high abrasion can be provided by the abovementioned configuration.

Description

Impact tools

The present invention relates to a power tool, and more particularly to an improved impact tool that applies impact torque.

¡General power tools that apply torque to fasteners such as nuts, bolts, and screws use either continuous drive or intermittent drive means. Compared to continuous drive, impact tools that provide intermittent output rotation based on intermittent drive can apply higher peak torque to the fastener, while at the same time providing relatively low torque (rebound) to the user. be able to. In addition, this type of impact tool has the advantage that the tool size is compact, and the configuration that realizes intermittent drive is generally used in applications such as screwing screws into wood. It helps to maintain the engagement between the part (bit) and the driven part (screw head). This is because the drive portion (bit) and the driven portion (screw head) are re-engaged during the non-drive period of the drive portion (bit).

As a means for realizing intermittent driving, a rotation mechanism (see FIG. 16) including a hammer 10 and an anvil 11 is generally used. The hammer 10 is connected to the input shaft via a cam mechanism, and is rotated by a motor until it collides with an anvil 11 connected to a fastener to be tightened. When subjected to an impact, the output shaft rotates by a predetermined amount due to the transmission of angular momentum. When the hammer 10 decelerates due to the collision with the anvil 11, the hammer 10 is separated from the anvil 11 by the cam mechanism, whereby the hammer 10 is accelerated again and can repeat the collision operation.

In addition, as a prior art document disclosing the conventional impact tool provided with the above-described hammer 10 or the like, for example, there is the following Patent Document 1 or the like.

JP 2000-42936 A US Pat. No. 3,342,021

However, the problem with impact tools that use the intermittent drive means described above is that they are typically accompanied by high noise, high vibration, high loss and high wear.

The present invention has been made in view of the above-mentioned problems, and its purpose is to enable a variable output rotational motion including intermittent motion and forward / reverse motion for a constant input rotational motion. The object is to address these problems by using a constantly meshing gearbox including non-circular gears.

Hereinafter, the present invention will be described. In addition, in order to make an understanding of this invention easy, the reference number of an accompanying drawing is attached in parenthesis writing, However, This invention is not limited to the form of illustration by it.

An impact tool according to the present invention is an impact tool that provides a rotational motion having a periodically changing angular velocity and / or torque designed to be connected to a ground at a given condition, wherein the angular velocity and / or Or an input shaft providing a rotational motion in which the torque is substantially constant during one revolution, an output shaft in which the angular velocity varies as a function of the angle of the input shaft, and the rotational motion of the input shaft as the output shaft. Two pairs including a first gear pair (1, 2) associated with the input shaft and a second gear pair (3, 4) associated with the output shaft. A gear box including the above gears (1, 2, 3, 4), and the gears (1, 2, 3, 4) have radiuses r ₁ (Θ) and r ₂ (Θ) of pitch circles, respectively. , r (Theta), and _{r 4} have a (theta), the theta is represents the angular position of the planetary shaft (7) connecting the gear (2) and a wheel (3), the gears (1, 2, 3, When the radius of 4) is at least an angle range of 0 ≦ Θ ≦ 2π, the following inequality:
r ₁ (Θ) · r ₃ (Θ) / r ₂ (Θ) · r ₄ (Θ)> 1
By configuring the drive train so as to satisfy the above, the rotational direction of the output shaft is reversed during at least a part of the drive cycle.

In the impact tool according to the present invention, when ζ is the damping ratio and wn is the rotational natural frequency of the system including the impact tool and connection to the ground, the output cycle frequency is
sqrt (2 × (1-2ζ)) wn
Is preferably set to be larger than the calculation cycle frequency defined by Note that “sqrt” in the above equation indicates a square root (the same applies hereinafter).

The impact tool according to the present invention is an impact tool that provides a rotational motion having a periodically changing angular velocity and / or torque designed to be connected to a ground under a given condition, And / or an input shaft that provides a rotational motion in which the torque is substantially constant during one revolution, an output shaft in which the angular velocity varies as a function of the angle of the input shaft, and the rotational motion of the input shaft A drive train for transmitting to the output shaft, comprising: a first gear pair (1, 2) associated with the input shaft; and a second gear pair (3, 4) associated with the output shaft. And a gear box having two or more pairs of gears (1, 2, 3, 4), a rotational natural vibration of a system including a damping ratio ζ and a connection wn to an impact tool and ground When the number, the output cycle frequency,
sqrt (2 × (1-2ζ)) wn
It is set so that it may become larger than the calculation cycle frequency defined by.

In the impact tool according to the present invention, it is preferable that the connection to the ground is provided by a user, and the output cycle frequency is a frequency greater than 14 Hz.

In the impact tool according to the present invention, the impact tool is used for tightening a screw, and the forward rotation motion (rotational motion in the tightening direction of the screw) of the output shaft is caused by the tool member and the screw. Can be configured such that subsequent reverse movement causes re-engagement of the tool member with the screw.

Furthermore, it is preferable that the impact tool according to the present invention is configured such that, when in use, the cycle frequency is substantially larger than the natural frequency of the entire system.

Furthermore, in the impact tool according to the present invention, the time during which the output shaft is rotating and the time during which the output shaft is stopped in order to reduce the torque acting on the ground (for example, the user who is gripping). The ratio can be set freely.

Furthermore, in the impact tool according to the present invention, the output torque for sensing the torque on the input side and calculating the torque on the output side using the known gear ratio and information on the angular position of the system therefrom. There may be further provided means for indirectly sensing.

Further, in the impact tool according to the present invention, the impact tool is used for tightening a screw, and avoids separating the tool member from the screw during a driving period between non-driving periods. In order to achieve this, the rotation angle of the output shaft can be configured to be sufficiently small.

Further, in the impact tool according to the present invention, the impact tool is used for tightening a screw, and a reverse rotation angle of the output shaft is slightly separated between the tool member and the screw during a driving period. Thereafter, the tool member and the screw can be re-engaged.

Further, in the impact tool according to the present invention, the rotating body (186) included in the gear box has a planetary shaft (7 (174)) connecting the gear (2 (173)) and the gear (3 (172)). The balance weight part (186a) for balancing with can be provided.

According to the present invention, it is possible to provide an impact tool that has solved the conventional problems such as high noise, high vibration, high loss and high wear.

FIG. 1 is a conceptual diagram for explaining the configuration of a non-circular gearbox according to the present embodiment. FIG. 2 is a graph showing the gear ratio as a function of the input angle Θ. FIG. 3 is a diagram illustrating a form in which the non-circular gears of the present embodiment are arranged in a planetary gear box configuration. FIG. 4 is a diagram showing a general screw head and an end face of a screw driving bit. FIG. 5 is a block diagram illustrating the configuration of the impact tool according to this embodiment. FIG. 6 is a graph showing the relationship between the natural frequency and the cycle frequency of the entire system according to this embodiment. FIG. 7 is a diagram showing another example embodiment that can be taken by the present invention. FIG. 8 is a diagram showing still another embodiment example that the present invention can take. FIG. 9 is a diagram showing an example of a non-circular planetary gear / non-circular sun gear pair for realizing the present invention. FIG. 10 is a vertical cross-sectional right side view showing the overall configuration of the impact tool according to the present embodiment. FIG. 11 is an exploded exploded perspective view of a main part for explaining a main part configuration of the impact tool according to the present embodiment. FIG. 12 is a diagram showing a non-circular planetary gear according to the present embodiment, where (a) in the drawing shows a rear side surface, and (b) in the drawing shows a cross section. FIG. 13 is a view showing a non-circular sun gear with an output shaft according to the present embodiment, in which (a) in the drawing shows a rear side surface and (b) in the drawing shows a cross section. FIG. 14 is a diagram for explaining a noise measurement method. FIG. 15 is a diagram showing still another embodiment example that can be taken by the present invention. FIG. 16 is a diagram illustrating a rotation mechanism composed of a hammer and an anvil generally used as means for realizing intermittent drive.

Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. The following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

FIG. 5 is a block diagram illustrating the configuration of the impact tool according to the present embodiment. The impact tool according to this embodiment uses, for example, a motor (electromagnetic, pneumatic, or other power) coupled to a conventional gear box 25 by a motor shaft 16 to achieve desired average torque characteristics and average speed characteristics. Motor 14).

The input shaft 26 installed in the gear box 25 provides driving force to the non-circular gear box 18 including non-circular gears, and then the non-circular gear box 18 drives the output shaft 17. The ratio between the input angular velocity and the output angular velocity of the non-circular gear box 18 can be expressed as a function of the angle of the input shaft 26. The output shaft 17 is generally separably connected to a mechanical fastener such as a nut or screw that is a target for transmitting impact torque.

FIG. 1 is a conceptual diagram for explaining a configuration of a non-circular gear box 18 according to the present embodiment. As shown in FIG. 1, the non-circular gearbox 18 includes an input gear 23 and an output gear 24, each of which has a radius that varies over their entire circumference. Here, the gear ratio is defined as follows.
ω ₂ = Rω ₁

Where ω ₁ is the input angular velocity provided by the input shaft 26 installed in the conventional gearbox 25, R is the gear ratio, and ω ₂ is the output angular velocity of the output shaft 17. In the two-gear drive train as shown in FIG. 1, the gear ratio can be known as follows from the ratio of the radii at the current contact points of the two gears 23 and 24 that are mated.
R = r ₁ / r ₂

In the above equation, r ₁ is the radius of the pitch circle of the input gear 23, and r ₂ is the radius of the pitch circle of the output gear 24. By having a pair of non-circular gears that vary in radius as a function of angle Θ, it is possible to achieve a gear ratio (see FIG. 2) that varies as a function of input angle Θ, and therefore R, Let r ₁ and r ₂ be replaced with R (Θ), r ₁ (Θ) and r ₂ (Θ).

In the arrangement described here, a constant speed input provides an output speed that varies with both the angle and time of the input shaft 26. The torque is T ₁ as input torque and T ₂ as output torque.
T ₂ = T ₁ / R (Θ)
This varying gear ratio makes it possible to provide a varying torque output.

In order to ensure that the torque transmitted to the ground 21 is lower than the torque applied by the output, the output cycle frequency is
sqrt (2 × (1-2ζ)) wn
("Calculated cycle frequency range (Calculated
Cycle Frequency Range) ”)
Is set to be larger than In the above equation, ζ is the damping ratio, and wn is the rotational natural frequency of the system including the impact tool and the connection to the ground 21. In the case of a user of an impact tool according to the present embodiment, this calculation cycle frequency range can be shown to be a frequency greater than 14 Hz.

A further improvement of this embodiment is that the above-described non-circular gears 23 and 24 are arranged in a planetary gear box configuration. As shown in FIG. 3, the pair of circular gears 1 and 2 can be combined with a pair of non-circular gears 3 and 4. As a modification, the configuration shown in FIG. 3 is reversed so that the pair of gears indicated by reference numerals 1 and 2 are non-circular gears and the pair of gears indicated by reference numerals 3 and 4 are circular gears. You can also. Further, all the gears can be non-circular gears.

The input shaft 5 is rigidly connected to the drive arm 6. As a result, when the input shaft 5 rotates, the drive arm 6 rotates by the same amount. As a result, the planetary shaft 7 circulates around the axis of the input shaft 5 with a constant radius. Planetary shaft 7 rotates freely about its own axis when driven by drive arm 6. The driven planetary gear 2 is rigidly connected to the planetary shaft 7. The angle of the planetary shaft 7 is called Θ. As the driven planetary gear 2 moves around the stationary sun gear 1, the driven planetary gear 2 thereby rotates about its axis, thereby driving the rotation of the planetary shaft 7. This rotation drives the drive planetary gear 3 rigidly connected to the planetary shaft 7. The drive planetary gear 3 then rotates the output sun gear 4 thereby driving the rotation of the output shaft 27.

The gear arrangement as shown in FIG. 3 is known from the prior art, for example, Patent Document 2 listed above.

The gear ratio of such a system is as follows.
R (Θ) = 1−r ₁ (Θ) · r ₃ (Θ) / r ₂ (Θ) · r ₄ (Θ)

Where Θ is the angle of the planetary shaft 7. If the gears 1, 2, 3 and 4 are circular, r ₁ (Θ) = r ₁ = constant, r ₂ (Θ) = r ₂ = constant, r ₃ (Θ) = r ₃ = constant, r ₄ ( Θ) = r ₄ = constant, and therefore the gear ratio R (Θ) = R = constant. However, when the pair of gears is non-circular as described above, R (Θ) generally varies as a function of Θ. Also, during a certain time range, if r ₁ (Θ) = r ₄ (Θ) and r ₂ (Θ) = r ₃ (Θ), then R (Θ) = 0 and the output stops. On the other hand, the input continues to rotate. As a result, intermittent driving is obtained.

The inertia associated with the input shaft 5 accelerates during the non-driving period and decelerates during the driving period. Thus, the torque at the output shaft 27 is a combination of, for example, a drive torque provided by a motor and a reaction to inertia deceleration. Therefore, such a configuration makes it possible to apply a higher torque than direct driving by a motor.

It is also possible to realize a similar system having an internal gear type on the stationary sun gear 1 and / or an internal gear type on the output sun gear 4.

Furthermore, the dependent form r _n (Θ) (n = 1, 2, 3, 4) of the gear pitch circle radius affects the rate of change of the output speed. In order to avoid sudden changes in speed, the dependent form of the gear pitch circle radius can be chosen so that the speed increases slowly enough. By increasing the speed relatively slowly, very high accelerations are avoided, resulting in a reduction in noise and vibration.

Other possible modifications are the angle r ₁ (Θ) · r ₃ (within an angle or range of angles from Θ = Θ _rev1 to Θ = Θ _rev2 (0 ≦ Θ _rev1 , Θ _rev2 ≦ 2π) during the cycle. Θ)> r ₂ (Θ) · r ₄ (Θ), and at some point, r ₁ (Θ) · r ₃ (Θ) <r ₂ (Θ) · r ₄ (Θ), Including selecting a pitch circle radius (ie, r ₁ (Θ) · r ₃ (Θ) / r ₂ (Θ) · r ₄ (Θ)> 1 when the angle range is 0 ≦ Θ ≦ 2π) And r ₁ (Θ) · r ₃ (Θ) / r ₂ (Θ) · r ₄ (Θ) <1. In this way, when Θ _rev1 <Θ <Θ _rev2 , an output that always reverses the rotation direction is obtained. This can be used for applications such as screwing screws into wood. During screwing, the continuous drive of screwing may cause a disconnection of the connection between the output shaft interface (often referred to as “bit”) and the driven part (screw head), This is a phenomenon known in the art as “cam-out”. In the present invention, the bit and screw head separation in a given cycle is avoided by first advancing by a small amount during each drive cycle. In addition, by reversing over an angle during non-drive, the bit and screw head re-engage, limiting or preventing camout over multiple cycles. This is shown in FIG. FIG. 4 shows an end view of a typical screw head 8 and screw drive bit 9. They are initially well aligned and during drive they begin to separate, and after the drive period, reverse rotation facilitates re-engagement.

Consider a configuration in which the motor 14 can transmit torque to the case 15 by a certain method, for example, electromagnetic field or air pressure. The motor 14 drives a non-circular gearbox 18 of one of the types described above via a connecting shaft (motor shaft 16). This non-circular gearbox 18 is mechanically or otherwise connected to the case 15 and the output shaft 17 and from there to a certain tool member 22.

Considering the total time taken from the start of one drive period to the next drive period, the “cycle period” of the output shaft 17 at the peak torque transmitted to the ground 21 (the reciprocal of this is the “cycle frequency”). ) Can be achieved. When this system is considered to be fixed to the ground 21 by a system approximate to the torsion spring 12 and the torsion damper 13, for example, a human arm, and has a certain rotational inertia, the natural frequency and cycle frequency of the entire system Determines the peak torque applied to ground 21. In the extreme case where the cycle frequency is infinite, the ground 21 receives the same peak torque that the tool member 22 receives. When the cycle frequency and the natural frequency of the system converge, the peak torque received by the ground 21 further increases. However, when the cycle frequency increases beyond the natural frequency of the entire system, the torque received by the ground 21 becomes lower than the peak torque.

FIG. 6 shows this effect at a natural frequency of 14 Hz, and the y-axis shows the “transmission rate” defined as the ratio of the output force to the input force, and is shown in dB. Therefore, by appropriately selecting the gear type, the cycle frequency can be selected to achieve this advantageous behavior. Further, the magnitude of the transmitted torque is determined by the ratio of the time during which the output shaft 17 is rotating and the time during which the output shaft 17 is stopped. Since the entire impact must be stored between the ground 21 and the tool member 22, if a high torque is applied to the tool member 22 for a short time, this is applied to the ground 21 for a longer time. Can be balanced with the much lower torques that are available. That is, the impact tool according to the present embodiment has means for allowing the ratio of the time during which the output shaft 17 is rotating and the time during which the output shaft 17 is stopped to be freely set in order to reduce the torque acting on the ground. By providing, the torque on the output side can be controlled.

Another advantage of the above-described embodiment is that a constant mesh between the input and output is achieved. Unlike the conventional impact tool in which there is no correlation between input torque and output torque, the configuration based on this embodiment has a correlation between input torque and output torque. Thereby, the input side torque can be sensed and the output side torque can be calculated therefrom using the known gear ratio and information about the angular position of the system. That is, the impact tool according to the present embodiment further includes means for indirectly sensing the output torque, whereby the output side torque can be calculated.

These means described above are useful, for example, in controlling the torque applied to the fastener. When an electromagnetic motor is used, the motor torque can be derived from information about current and voltage. Therefore, as an example of this embodiment, the present invention includes electronic torque sensing.

One advantage of this embodiment described above is that it is less noisy than existing impact tools due to the removal of the impact mechanism and more gradual acceleration of the output shaft. Similarly, this embodiment reduces vibrations created by the device. Furthermore, this embodiment has a low loss by replacing the highly impaired collision and sliding contact with the rolling contact of the gear. This further provides the advantage of low wear and even longer life.

Those skilled in the art will appreciate that the impact tool according to this embodiment described above can provide benefits to power tools in general including a driver drill and an impact driver. Furthermore, such a system can be used when a rotary reciprocation is required, for example in the case of a hedge trimming machine.

Also, for example, the present embodiment can be applied to other devices, particularly a reciprocating saw device, by using a rack and pinion to realize a simple “rotation-linear” conversion.

In addition, another advantage of this embodiment is that the characteristics of the device based on this embodiment allow higher output torque than a prior art direct drive device such as a driver drill for a given combination of motor and gearbox. Thus, the device size can be reduced when the torques are equal. The use of the impact mechanism of this embodiment further reduces the torque applied by the device to the mechanical “ground (eg user)” for a given output torque when compared to a direct drive device such as a driver drill. Can be made. Still further, in applications where contact may be lost (such as threading a screw using a bit), this causes loss of engagement because reversal allows re-engagement between the bit and the screw head. Can be avoided.

The preferred embodiments of the present invention have been described above, but the technical scope of the present invention is not limited to the scope described in the above embodiments. Various modifications or improvements can be added to the embodiment.

A specific embodiment suitable for many applications including, for example, use as a replacement tool for a type of power tool known as an impact driver is shown in FIG. The input shaft 71 drives a rotator 78 in which the planetary shaft 74 is mounted, and the planetary shaft 74 is free to rotate about its own axis. A circular planetary gear 73 and a non-circular planetary gear 72 are mounted on the planetary shaft 74. These gears 72 and 73 are connected to each other. When a considerable torque capacity from the gear box is required, the gears 72 and 73 are preferably connected by being integrally formed. The circular planetary gear 73 is rotated by the action of a circular sun gear 76 connected to the mechanical ground. Therefore, the non-circular planetary gear 72 is driven by the circular planetary gear 73. As a result, the non-circular planetary gear 72 drives the non-circular sun gear 75. The non-circular sun gear 75 is connected to the output shaft 77 and drives the output shaft 77.

The embodiment shown in FIG. 7 has considerable advantages over the configuration shown in FIG. Connecting the circular sun gear 76 to ground at the output shaft 77 end, rather than the input shaft 71 end of the mechanism, allows the planetary shaft 74 to be supported at both ends in the rotator 78. By supporting the planetary shaft 74 at both ends in the rotator 78, the vertical load at both ends of the planetary shaft 74 is reduced for a given moment applied to the planetary shaft 74, forming a higher strength gearbox, and more Enables a lighter and more compact gearbox structure. Furthermore, this configuration allows the circular planetary gear 73 and the non-circular planetary gear 72 to be formed as a single part without having to accommodate a bearing between these gears 72,73. Since a considerable torque is transmitted between the gears 72 and 73, the strength of the unit is increased by this configuration.

¡If an additional reduction gearbox is required on the input shaft, the overall system size may be reduced. Yet another embodiment shown in FIG. 8 shows an additional reduction gearbox constructed directly on the rotating body 86. The input shaft 85 drives a sun gear 81, which acts on one or more planetary gears 82, which travel in a circular internal gear 84 connected to ground. A shaft 83 of the planetary gear 82 provides rotational drive about the axis of the rotator 86. Further, the shaft 83 can be conveniently installed on the rotating body 86. This achieves considerable simplification and size reduction compared to installing an additional separate reduction gearbox at the input of the configuration shown in FIG.

When a 4.5 x 90 mm screw is screwed into a dried pine with a prior art impact driver, it is generally a hammer at the midpoint of the screwing (when approximately 45 mm of the screw is screwed into wood). It is known that the screw rotates 90 degrees with a single collision. Since the time required for one collision is 15 ms, the frequency of this pulse train is 67 Hz. This is much higher than the natural frequency of the tool / user system. Further, the torque transmitted to the user is a time average of the torque applied to the screw. Thus, the user is not subjected to high torque pulses applied to the screw. In addition, a general impact driver analysis has found that a 10 degree reversal of the bit to the screw is common under the worst case camout condition.

By selecting the appropriate non-circular gear type and circular gear size, the behavior of the prior art impact driver described above can be used to create a gear box with teeth always engaged (no collision) using the present invention. It is possible to have a similar behavior within. An example of a non-circular planetary gear 91 / non-circular sun gear 92 pair that accomplishes this is shown in FIG. Each gear 91, 92 has 14 teeth of a substantially similar module. These gears 91 and 92 are arranged in a gear box of the type shown in FIG. 7 or FIG. 8 in a circular gear having a planetary-sun ratio = 0.765 (for example, a circular planetary gear having a pitch circle diameter of 13 mm and a pitch circle diameter). 17 mm circular sun gear). In this configuration, the output shaft (reference numeral 77 in FIG. 7 and reference numeral 87 in FIG. 8) is rotated forward by 95 degrees, and thereafter, the output shafts 77 and 87 are reversed by 10 degrees.

Note that the forward rotation angle and the reverse rotation angle of the output shafts 77 and 87 described above vary depending on the configuration conditions of the gear group constituting the present invention. For example, the fact that the reverse angle of the output shafts 77 and 87 is generally about 10 degrees is merely an example of representative numerical values. By appropriately changing the constituent members of the present invention within the scope of the inventive idea, the behavior of the impact tool according to the present invention can be changed to various settings.

When these types are used in the configuration shown in FIG. 7, when the input shaft 71 is driven at 1,556 rpm, the drive / reverse cycle of the output shaft 77 occurs at 34 Hz. This configuration achieved this lower noise level during operation as this can be achieved without collision of prior art devices.

Alternatively, the configuration shown in FIG. 8 can be used. When the pitch circle diameter of the circular sun gear 81 is 5 mm, the pitch circle diameter of the circular planetary gear 82 is 17.5 mm, and the pitch circle diameter of the circular internal gear 84 is 40 mm, the speed is reduced between the input shaft 85 and the rotating body 86. A ratio of 9: 1 is achieved. Thus, when the input shaft 85 is rotated at 14,000 rpm (a non-anomalous speed of a prior art motor used with similar power tools), the drive / reverse cycle occurs at 34 Hz.

Therefore, it is possible to achieve the beneficial characteristics of an impact driver when compared to a driver drill. These beneficial properties include similar screw threading times, less camout, high peak torque applied to the screw and lower peak torque applied to the user, and size reduction for a given torque output Is included. Furthermore, significantly lower noise, lower vibration, higher efficiency and lower wear are achieved compared to impact drivers.

In the above-described embodiment, the mechanism for limiting and preventing the cam-out phenomenon over a plurality of cycles has been described with reference to FIG. That is, in this embodiment, the bit and screw head separation in a given cycle is avoided by first rotating it forward by a small amount during each driving cycle. Furthermore, even if they begin to separate during driving, re-engagement can be facilitated by reverse rotation after the driving period. Further, it has been described that these operations are realized by a two-gear drive train or the like that is always meshed and installed in the non-circular gear box 18. However, further suitable improvements can be made to the above-described embodiments, for example, the output shaft between non-drive periods to avoid separating the tool member from the screw during the drive period. It is preferable that the rotation angle is sufficiently small. As another improvement, it is also preferable that the reverse angle of the output shaft is configured to re-engage the tool member and the screw after a slight separation between the tool member and the screw during the driving period. is there. Such improvement makes it possible to reliably prevent the cam-out phenomenon.

Further, the configuration illustrated in FIG. 7 and FIG. 8 and the like merely exemplifies one form that the present invention can take. The present invention has the above-described basic configuration, and various modifications can be employed within the scope of exhibiting the same operational effects. For example, FIG. 15 is shown as a modification of the embodiment shown in FIG. In the embodiment shown in FIG. 15, the non-circular planetary gear 72 and the non-circular sun gear 75 are arranged on the output shaft 77 side, and the circular planetary gear 73 and the circular sun gear 76 are arranged on the input shaft 71 side. It is different from FIG. In the embodiment shown in FIG. 15, a rotating body 78 is installed at the tip of the input shaft 71. When the input shaft 71 drives the rotating body 78, the planetary shaft 74 attached to the rotating body 78 performs planetary motion. This planetary shaft 74 rotates freely about its own axis. A non-circular planetary gear 72 and a circular planetary gear 73 are mounted on the planetary shaft 74. These gears 72 and 73 are connected and fixed to each other with respect to the planetary shaft 74. The circular planetary gear 73 is rotated by the action of a circular sun gear 76 connected to the mechanical ground. Therefore, the non-circular planetary gear 72 is rotationally driven as the circular planetary gear 73 rotates. As a result, the non-circular planetary gear 72 drives the non-circular sun gear 75. Since the output shaft 77 is connected to the non-circular sun gear 75, the output shaft 77 is rotationally driven as the non-circular sun gear 75 is rotationally driven. Note that the embodiment shown in FIG. 15 has the advantage that the balance of rotational motion is good because a plurality of non-circular planetary gears 72 are arranged so as to be symmetrical with respect to the non-circular sun gear 75. Yes.

It is apparent from the scope of the claims that the embodiment added with such changes or improvements can also be included in the technical scope of the present invention.

Next, an example in which the embodiment illustrated with reference to FIGS. 7 and 8 is specifically applied to an impact tool will be described with reference to FIGS. Here, FIG. 10 is a vertical cross-sectional right side view showing the overall configuration of the impact tool according to the present embodiment. FIG. 11 is an exploded exploded perspective view of a main part for explaining a main part configuration of the impact tool according to the present embodiment. Further, FIG. 12 is a diagram showing a non-circular planetary gear according to the present embodiment, and FIG. 13 is a diagram showing a non-circular sun gear with an output shaft according to the present embodiment. (B) in a figure has shown the cross section.

As shown in FIGS. 10 and 11, the impact tool 100 according to the present embodiment is a battery-type impact tool 100, and is detachably attached to a housing 110 that houses a drive source such as a motor 111 and a lower end portion of the housing 110. And a battery pack 130 for supplying driving power to the motor 111.

The housing 110 includes a housing upper body 110a that houses the drive mechanism 115 corresponding to the motor 111 and the non-circular gear box 18 according to the above-described embodiment, a housing central body 110b that receives a grip from the user, and a battery pack 130. And a housing lower body 110c having a connection mechanism. Power wiring is provided from the housing lower body 110 c to the housing upper body 110 a via the housing central body 110 b, so that driving power charged in the battery pack 130 can be supplied to the motor 111. Further, an operation switch 112 is provided on the upper front side of the housing central body 110b, and a user who holds the housing central body 110b can operate the operation switch 112 suitably.

The drive mechanism 115 installed in front of the motor 111 is a specific implementation of the mechanism of the present invention described with reference to FIGS. That is, the drive mechanism 115 according to the present embodiment includes a sun gear 181 connected to a motor shaft 111a included in the motor 111, two planetary gears 182 and 182 meshingly connected around the sun gear 181 and two planetary gears. The gears 182 and 182 further include a circular internal gear 184 that surrounds the outer periphery. When the motor shaft 111a rotates by supplying electric power to the motor 111, the motor shaft 111a drives the sun gear 181. The sun gear 181 acts on the two planetary gears 182 and 182, and the planetary gears 182 and 182 It moves in the circular internal gear 184 connected to the housing upper body 110a.

A rotating body 186 is installed in front of the two planetary gears 182 and 182. The shaft 183 of the planetary gear 182 is connected to this rotating body 186 and provides rotational drive about the axis of the rotating body 186.

A planetary shaft 174 is installed at a position eccentric from the rotation center of the rotating body 186. The planetary shaft 174 is installed in a form that is accommodated inside the rotating body 186, and both shaft ends of the planetary shaft 174 are bearings 174 a and 174 b such as needle bearings installed in the rotating body 186. It is pivotally supported by.

Further, the planetary shaft 174 is provided with a circular planetary gear 173 at the front shaft end and a non-circular planetary gear 172 at the rear shaft end. These gears 172 and 173 are rigidly connected to each other, and can rotate freely around the axis of the planetary shaft 174.

The circular planetary gear 173 meshes with a circular sun gear 176 fixedly connected to the housing upper body 110a as a mechanical ground. That is, when the rotating body 186 is driven to rotate by the rotation of the two planetary gears 182 and 182, the planetary shaft 174 circulates around the circular sun gear 176, and as a result, the circular sun gear 176 that is fixedly installed. The circular planetary gear 173 rotates and revolves around.

As the circular planetary gear 173 is rotated, the non-circular planetary gear 172 is also rotated in the same manner. Since the non-circular planetary gear 172 meshes with the non-circular sun gear 175 connected to the output shaft 177, the non-circular sun gear 175 is rotationally driven in accordance with the rotational drive of the non-circular planetary gear 172, and as a result As a result, the output shaft 177 is rotationally driven. Note that the rotation axis center of the output shaft 177 connected to the non-circular sun gear 175 overlaps the rotation center axis of the rotating body 186. The shaft end on the rear side of the output shaft 177 is supported by a bearing installed in the rotating body 186, and the shaft end on the front side is connected to the bit holder 179. Therefore, a tool such as a driver installed in the bit holder 179 rotates in accordance with the rotational drive of the output shaft 177 so that the work can be performed on the outside.

Note that, as described above, the rotating body 186 is rotationally driven in accordance with the planetary movement of the planetary gear 182, but the planetary shaft 174 installed therein is eccentrically installed. Further, the planetary shaft 174 is provided with weight members such as a non-circular planetary gear 172 and a circular planetary gear 173. Therefore, in order for the rotator 186 to preferably rotate, it is necessary to provide a balance weight for balancing with a weight member such as the planetary shaft 174. Therefore, in the rotating body 186 according to the present embodiment, as shown in FIG. 11, the balance body portion having a half structure at the center of the body of the rotating body and having a half structure at a position facing the installation position of the planetary shaft 174. The structure which provides 186a was employ | adopted. By installing the balance weight portion 186a, the rotating body 186 can perform a stable rotational movement, and the impact tool 100 having stable operability can be realized.

Next, the operation of the impact tool 100 according to the present embodiment will be described with reference to FIG.

In the impact tool 100 according to the present embodiment, the motor shaft 111a is rotationally driven by the drive of the motor 111, and the rotational force of the motor shaft 111a rotates the sun gear 181. When the sun gear 181 rotates, the two planetary gears 182 and 182 installed between the sun gear 181 and the circular internal gear 184 perform planetary motion. Since the shaft 183 of the planetary gear 182 is connected to the rotating body 186, the rotating body 186 is rotationally driven by the planetary gears 182 and 182 performing planetary motion.

When the rotating body 186 is driven to rotate, the circular planetary gear 173 is rotated by the action of the circular sun gear 176 fixedly connected to the housing upper body 110a. It is rotationally driven in the same manner as the planetary gear 173. Since the non-circular planetary gear 172 and the circular planetary gear 173 are installed with respect to the planetary shaft 174 installed inside the rotating body 186, the two gears 172 and 173 move around the axis of the planetary shaft 174. While rotating freely, the rotary body 186 rotates around the rotation center axis.

As described above, the non-circular planetary gear 172 that performs planetary movement is engaged with the non-circular sun gear 175, and the output shaft 177 is connected to the non-circular sun gear 175. Then, since the non-circular sun gear 175 rotates in accordance with the planetary motion of the non-circular planet gear 172, the rotational driving force is transmitted to the output shaft 177, and a predetermined torque can be applied to the outside. ing.

As described in the above-described embodiment, in the impact tool 100 according to the present example, the output shaft 177 is caused by the action of the non-circular planetary gear 172 and the non-circular sun gear 175 which are two non-circular gears. In addition to normal rotation, reverse operation is performed in a predetermined cycle period. By such an operation, a suitable effect such as prevention of come-out can be obtained.

Further, unlike the conventional impact tool including the hammer 10 and the like, the impact tool 100 according to the present embodiment has a configuration in which a mechanism as an impact tool is realized by a plurality of non-circular gears. It has the favorable advantage of low noise at times. This advantage is made clear by the analysis result of the comparative measurement of noise using the conventional impact tool and the impact tool 100 of the present embodiment shown in FIG. 14 and Table 1. Here, FIG. 14 is a diagram for explaining a noise measurement method.

The noise measurement method implemented this time is to measure the noise generated when a wood screw of φ4.5 × 90 mm is fastened to a test piece 190 made of dry rice pine (Dry Pine). The measurement position of the noise was set to a position 1 m away from the impact tool with respect to the rear direction, left direction, upper direction, and lower direction of the impact tool. In the noise measurement, an A characteristic frequency weighted sound pressure level (A weighted sound pressure level) is added. Moreover, the impact tool used for the noise measurement is an impact tool including the impact tool 100 according to the present embodiment described with reference to FIG. 10 and the like, the conventional hammer 10 represented by the above-mentioned Patent Document 1, and the like. Table 1 shows the measurement results of noise measured based on the above conditions. Table 1 is a table comparing noise measurement results under load.

As is clear from Table 1, it was confirmed that the impact tool 100 according to the present example had a lower noise level at all measurement positions than the impact tool (impact driver) according to the prior art. Further, even when the average values of the measured noise results are compared, the impact tool 100 according to the present embodiment achieves lower noise with a difference of 5.0 dB (A), and the superiority of the present invention is achieved. confirmed.

1 stationary sun gear, 2 driven planetary gear, 3 driving planetary gear, 4 output sun gear, 5 input shaft, 6 driving arm, 7 planetary shaft, 8 screw head, 9 screw drive bit, 10 hammer, 11 anvil, 12 twist Spring, 13 Torsional damper, 14 Motor, 15 Case, 16 Motor shaft, 17 Output shaft, 18 Non-circular gearbox, 21 Ground, 22 Tool member, 23 Input gear, 24 Output gear, 25 (Conventional) gearbox, 26 Input shaft, 27 output shaft, 71 input shaft, 72 non-circular planetary gear, 73 circular planetary gear, 74 planetary shaft, 75 non-circular sun gear, 76 circular sun gear, 77 output shaft, 78 rotating body, 81 sun gear, 82 Planetary gear, 83 shaft, 4 circular internal gear, 85 input shaft, 86 rotating body, 87 output shaft, 91 non-circular planetary gear, 92 non-circular sun gear, 100 impact tool, 110 housing, 110a housing upper body, 110b housing central body, 110c housing lower body , 111 motor, 111a motor shaft, 112 operation switch, 115 drive mechanism, 130 battery pack, 172 non-circular planetary gear, 173 circular planetary gear, 174 planetary shaft, 174a, 174b bearing, 175 non-circular sun gear, 176 circular sun Gear, 177 output shaft, 179 bit holder, 181 sun gear, 182 planetary gear, 183 shaft, 184 circular internal gear, 186 rotor, 186a balance weight part, 190 test piece.

Claims (11)

1. An impact tool that provides a rotational motion with a periodically varying angular velocity and / or torque designed to be connected to a ground at a given condition,
   An input shaft providing a rotational motion in which the angular velocity and / or torque is substantially constant during one revolution;
   An output shaft in which the angular velocity varies as a function of the angle of the input shaft;
   A drive train for transmitting rotational movement of the input shaft to the output shaft, the first gear pair (1, 2) associated with the input shaft and the second gear pair associated with the output shaft A gear box comprising two or more pairs of gears (1, 2, 3, 4) including (3, 4);
   Including
   The gears (1, 2, 3, 4) have pitch circle radii r ₁ (Θ), r ₂ (Θ), r ₃ (Θ) and r ₄ (Θ), respectively;
   Θ represents the angular position of the planetary shaft (7) connecting the gear (2) and the gear (3);
   When the radius of the gear (1, 2, 3, 4) is at least an angle range of 0 ≦ Θ ≦ 2π, the following inequality:
   r ₁ (Θ) · r ₃ (Θ) / r ₂ (Θ) · r ₄ (Θ)> 1
   An impact tool characterized in that the rotation direction of the output shaft is reversed during at least a part of a drive cycle by configuring the drive train to satisfy the above.
2. The impact tool according to claim 1,
   When ζ is the damping ratio and wn is the natural rotational frequency of the system including the impact tool and connection to the ground,
   The output cycle frequency is
   sqrt (2 × (1-2ζ)) wn
   An impact tool characterized by being set to be larger than a calculation cycle frequency defined by
3. An impact tool that provides a rotational motion with a periodically varying angular velocity and / or torque designed to be connected to a ground at a given condition,
   An input shaft providing a rotational motion in which the angular velocity and / or torque is substantially constant during one revolution;
   An output shaft in which the angular velocity varies as a function of the angle of the input shaft;
   A drive train for transmitting rotational movement of the input shaft to the output shaft, the first gear pair (1, 2) associated with the input shaft and the second gear pair associated with the output shaft A gear box comprising two or more pairs of gears (1, 2, 3, 4) including (3, 4);
   Including
   When ζ is the damping ratio and wn is the natural rotational frequency of the system including the impact tool and connection to the ground,
   The output cycle frequency is
   sqrt (2 × (1-2ζ)) wn
   An impact tool characterized by being set to be larger than a calculation cycle frequency defined by
4. In the impact tool according to claim 2 or 3,
   A connection to the ground is provided by the user;
   The impact tool, wherein the output cycle frequency is a frequency greater than 14 Hz.
5. The impact tool according to any one of claims 1 to 4,
   The impact tool is used to tighten screws,
   An impact tool characterized in that forward rotation of the output shaft causes separation of the tool member and the screw, and subsequent reverse movement causes re-engagement of the tool member and the screw.
6. The impact tool according to any one of claims 1 to 5,
   An impact tool characterized in that, when in use, the cycle frequency is substantially larger than the natural frequency of the entire system.
7. The impact tool according to any one of claims 1 to 6,
   An impact tool, wherein a ratio of a time during which the output shaft is rotating and a time during which the output shaft is stopped can be set in order to reduce torque acting on the ground.
8. The impact tool according to any one of claims 1 to 7,
   Means for indirectly sensing the output torque for sensing the input side torque and calculating the output side torque therefrom using a known gear ratio and information about the angular position of the system therefrom; Impact tool characterized by
9. In the impact tool according to claim 5,
   The impact tool is used to tighten screws,
   The impact is characterized in that the rotation angle of the output shaft is configured to be sufficiently small in order to avoid separating the tool member from the screw during a driving period between non-driving periods. tool.
10. In the impact tool according to claim 5,
    The impact tool is used to tighten screws,
    Impact tool characterized in that the reverse angle of the output shaft is configured to re-engage the tool member and the screw after a slight separation of the tool member and the screw during the drive period .
11. In the impact tool according to claim 1 or 2,
    The balance weight part for the rotating body (186) included in the gearbox to balance the planetary shaft (7 (174)) connecting the gear (2 (173)) and the gear (3 (172)). An impact tool comprising (186a).

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