JP2002168311A - Planetary transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planetary transmission capable of securing the smooth change of ring gears by separating the timing of reset and the timing of power cut-off and contributing to the maintenance of parts around the ring gears. SOLUTION: The timing of reset is separated from the timing of power cut-off, that is the timing of return of a trigger 21. After the power cut-off, the reset is executed after the energy of rotary motion with the inertia of the ring gears is sufficiently relaxed. Therefore, deformation, breaking, abrasion of related parts caused by the collision of a selective engagement member 15 and the ring gears 8 or such a malfunction as chattering or the like can be securely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary transmission that uses a planetary mechanism to shift gears, and more particularly to a planetary transmission that automatically shifts with an increase in load.

[0002]

2. Description of the Related Art In general, as a planetary transmission, a plurality of planetary mechanisms are arranged in an axial direction and a plurality of members in the planetary mechanism are selectively restrained to rotate, whereby a plurality of speed ratios other than 1: 1 are provided. There is something that can be obtained. With a power tool using such a planetary transmission, when screwing or drilling work, the initial work can be performed with low torque and high speed, and the final work can be performed with high torque and low speed. Result.

For example, Japanese Patent Application Laid-Open No. 63-186054 discloses that the above-mentioned shift according to the magnitude of the load, that is, a low-torque high-speed rotation at a low load, and a high-torque low-speed rotation at a high load is automatically performed. A planetary transmission is shown. This is because a plurality of planetary mechanisms including a sun gear, a planetary gear meshing with the sun gear, and a ring gear concentric with the sun gear and meshing with the sun gear are provided in the axial direction, and among the ring gears that are freely rotatable in each planetary mechanism. A selective locking member for selectively preventing one of the rotations is provided, and the selective locking member moves in accordance with a load applied to the ring gear to switch a ring gear for preventing rotation. I have.

Further, Japanese Patent Laid-Open Publication No. Hei 7-208604 discloses a problem with the planetary transmission described above, such as noise and vibration caused by frequent selective locking in response to a load change during operation, and a shortened life due to consumption of related parts. In order to cope with this, the latch means for latching the selective locking member after the switching operation of the ring gear engaged with the selective locking member by the switching means, and the latch is released when the rotational power is stopped, and By providing reset means for returning the stop member to the initial state, switching of the ring gear with which the selective lock member is engaged due to an increase in load, latching of the selective lock member by latch means, and resetting by stopping rotation power It is proposed that the state be maintained until the latch is released by the means.

[0005]

However, even in the improved example having the above-mentioned reset means, the reset means releases the latch means in conjunction with the trigger handle for the power switch. Since the reset is performed immediately after the power is turned off, at the time of resetting to the initial state, the ring gear related to the reset still continues to rotate due to inertia (FIG. 7: In this case, the trigger reset time is 1.9 msec). On the other hand, the braking time of the ring gear is 120 msec). For this reason, there is a problem in that the possibility of shape change, breakage, wear and the like of the related parts due to the collision of the selective locking member with the ring gear cannot be completely eliminated yet.

Further, since the reset means is formed by an elastic body (coil spring) constantly urged to the slider, the elastic force applied by the elastic body and the force generated by the rotational motion due to the inertia of the reset side ring gear. Due to the mechanical balance on the selective locking member with the axial component force of the above, even if the locking groove of the reset side ring gear and the locking member come into contact with each other, they do not immediately fit, and the chattering is not immediately performed. Inconveniences such as occurrence may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and separates reset timing from power cutoff timing to ensure smooth switching of a ring gear engaged with a selective locking member. It is an object of the present invention to provide a planetary transmission that can contribute to the maintenance of a locking member and parts around a ring gear.

[0008]

According to a first aspect of the present invention, there is provided a planetary transmission apparatus comprising: a sun gear connected to at least a rotary driving means; a planet gear meshing with the sun gear; Among the ring gears having a plurality of planetary mechanisms in the axial direction corresponding to mutually different gear ratios and including a ring gear concentrically meshing with the planetary gears, and being rotatable in the planetary mechanism. A selective locking member capable of selectively preventing one rotation of the ring gear is provided, and the mutually adjacent ring gears engaged with the selective locking member in accordance with the load on the ring gear are moved from a low torque high speed side. In a planetary transmission provided with switching means for switching to a high-torque low-speed side, the switching after the switching operation of the ring gear with which the selective locking member is engaged by the switching means. Latch means for latching a locking member, and rotational kinetic energy due to inertia of the low-torque high-speed side ring gear with which the selective locking member was engaged before the switching operation after the power supply of the rotation driving means was stopped. And a reset means for releasing the latch and returning to an initial state in which the selective locking member is engaged with the low-torque high-speed side ring gear after sufficiently relaxed. .

According to a second aspect of the present invention, in the planetary transmission according to the first aspect, the selective locking member has a slider movable at least in the axial direction, The ring gear is configured to be selectively engageable with only one of the ring gears related to the adjacent switching operation, and the ring gear to be engaged can be changed by axial movement of the slider. is there.

According to a third aspect of the present invention, in the planetary transmission according to the first or second aspect, the ring is related to the switching operation in which the selective locking member is adjacent in the axial direction. One of the gears has a shifting load torque setting and locking function, and the other of the ring gears involved in the switching operation has a locking function.

According to a fourth aspect of the present invention, in the planetary transmission according to any one of the first to third aspects, the latch means is configured to switch the slider after the switching operation. It is characterized in that it prevents movement in the reverse direction.

According to a fifth aspect of the present invention, in the planetary transmission according to any one of the first to fourth aspects, the reset means has at least a trigger handle for a power switch. The latch operation by the latch means is released by the pull-in operation.

According to a sixth aspect of the present invention, in the planetary transmission according to the fifth aspect, the reset means is linked with the trigger handle by a connecting rod connected to the slider. It is characterized by the following.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the planetary transmission of the present invention is not limited to the embodiment described below, and it is needless to say that various changes can be made without departing from the gist of the present invention.

FIGS. 1 to 4 show an embodiment of a planetary transmission used for an electric tool such as an electric drill driver. As shown in FIG. 1, a motor mount for closing one end opening of a gear case 1 is shown. A sun gear 4 having gears having different numbers of teeth is fixed to an output shaft 3 of a motor (not shown) attached to the motor 2, and a plurality of sun gears 4 arranged in the axial direction are provided. Individual planetary gears 5, 6
Are engaged. The two planetary gears 5 and 6 have different numbers of teeth from each other and transmit the output to one carrier 7. The two planetary gears 5 and 6 rotate individually around the carrier 7 while being shifted by 60 ° in the rotational direction. Do
It has the same orbit.

Of the two ring gears 8, 9 arranged concentrically with the carrier 7 and arranged in the axial direction, the ring gear 8 meshes with the planetary gear 5, and the ring gear 9 meshes with the planetary gear 6. ing. The two ring gears 8 and 9 have different inner diameters but the same outer diameter, and a plurality of cam ridges 10 and 11 are formed on each outer peripheral surface at equal intervals in the circumferential direction. The output of the carrier 7 is reduced by another planetary gear 12 and transmitted to the output shaft 13. The final stage ring gear 14 meshing with the planetary gear 12 has a cam ridge (not shown) projecting in the axial direction formed on the outer periphery, and is set so as to change the load in conjunction with a clutch handle (not shown). It functions as a torque limiter (clutch) for setting an engaged state by a coil spring (not shown). A description of this point will be omitted.

FIG. 2 is a bottom view ((a) a high-speed side ring gear locked state, (b) a shifting state, (c) a low-speed side ring gear locked state) showing a change in a locked state before and after a gear shift. 3 and 4 are diagrams showing the relationship between the trigger operation and the speed change mechanism. As shown in FIG. 2, the ring gears 8 and 9 are selectively locked with the selective locking member 15 to switch the gear ratio.
The selective locking member 15 has a slider 16 formed at an outer peripheral opening of the gear case 1 so as to be movable in the axial direction, and locking pieces 18 and 19 described later. That is, the main selection locking member 15
Is configured to selectively obtain a state of engagement with the cam ridge 10 on the outer peripheral surface of the high-speed side ring gear 8 and a state of engagement with the cam ridge 11 of the outer peripheral surface of the low-speed side ring gear 9. .

As means for selectively changing the engagement state, a dynamic balance between the peripheral force of the high-speed ring gear 8 with respect to the torque applied to the output shaft 13 and the elastic force of the latch spring 17 biased by the slider 16 is provided. (Fig. 2
(a), FIG. 3). That is, when the torque applied to the output side increases and the peripheral force of the high-speed side ring gear 8 deviates from the mechanical equilibrium against the elastic force applied thereto (FIG. 2B), it is pushed out of the high-speed side ring gear 8. The locking piece 18 of the selected locking member 15 is released from the engagement state with the high-speed side ring gear 8, and the other locking piece 19 engages with the low-speed side ring gear 9 (FIG. 2 ( c), FIG. 3). At this time, since the slider 16 moves with a speed in the axial direction via the locking piece, it is necessary to set the positioning of the slider 16 itself with a member capable of relaxing the impact. That is, the gear case 1 and the like may be broken by an impact. In the present embodiment, the slider 16 is positioned by an elastic body (NBR rubber) 20 fixed in the Z-axis direction (FIG. 3).

According to the variables shown in FIG. 4, this dynamic balance equation is Tc = PZ (μ ₂ + tan θ ₂ ) (1-μ ₂ tan θ ₂ ) ^-1 (tan ^-1
represented by θ ₁ -2μ ₁₎ ^-1. Here, Tc is the transmission torque, P is the latch spring force, and the reduction ratio of the high speed side ring gear 8 is
When i ₁ and the reduction ratio of the final stage ring gear 14 are i ₃ , Z
= i ₁ × i ₃ , μ ₁ is the friction coefficient between the locking piece 18 and the high-speed ring gear cam ridge 10, μ ₂ is the friction coefficient between the latch spring 17 and the slider 16, θ ₁ is the high-speed ring gear cam ridge 1
The angle 0 and θ ₂ are the inclination angles of the slider 16.

Here, the contact angle (θ ₁ -π / 2) between the high speed side ring gear cam peak 10 and the high speed side ring gear locking piece 18 is the axial component of the force applied to the locking piece 18 by the high speed side ring gear 8. Therefore, the gear ratio needs to be set large enough to smoothly switch the gear ratio by the mechanism described above (FIG. 2). On the other hand, when the low-speed side ring gear 9 is locked, the cam ridges 11 on the outer periphery of the ring gear 9 are arranged at equal intervals in the axial direction, and the force applied to the locking piece 19 from the low-speed side ring gear 9 in the axial direction Since no component is required, the low-speed side ring gear cam peak 1
1 and the contact angle between the low-speed side ring gear locking piece 19 are set sufficiently small (that is, substantially parallel to the axial direction) (FIG. 2). In addition to this, the slider 16 is held at a position where the slider 16 is locked to the low-speed ring gear by the elastic force of the latch spring 17, thereby preventing the slider 16 from moving in the axial direction toward the high-speed ring gear 8. Play a function
(FIG. 3).

As shown in FIGS. 3 and 4, in the reset means of this embodiment, a connecting rod 22 for interlocking with the trigger 21 is provided on the slider 16 and the connecting rod 22 is attached to the trigger 21 from both sides. An elastic body 23 for guiding is provided. When the slider 21 is locked with the low-speed side ring gear 9 and the trigger 21 returns, the elastic body 2
3 is configured so that the cam ridges 24 provided on the base 3 come into contact with the connecting rod 22 (FIG. 3), and a force for axially moving the slider 16 to the initial state when the trigger 21 is retracted is applied (FIG.
). When the slider 16 is in the initial state, the force for moving it in the axial direction increases, comes to oppose the elastic force of the elastic body 23, and the connecting rod 22 rides over the cam peak 24, so that no moving force is applied. , The trigger 21 is retracted to the maximum stroke (FIG. 3). Power supply by pulling in the trigger 21 is performed after resetting the initial state.

As described above, the reset timing is separated from the power shutdown, that is, the return timing of the trigger 21. After the power shutdown, the rotational kinetic energy due to the inertia of the ring gear can be sufficiently reduced and reset. Failures such as shape change, breakage, wear and the like, and chattering and other troubles of related components due to the collision of the member 15 with the ring gear 8 can be reliably prevented. Furthermore, if the resistance applied to the elastic body 23 is set high when the trigger 21 is retracted, and the resistance applied to the elastic body 23 is set low when the trigger 21 returns, the reset can be performed reliably and the workability of the user can be improved. This also makes it possible to reduce the holding force of the slider 16 by the latch spring 17 in a state where the slider 16 is locked with the high-speed side ring gear, thereby reducing the effect on the latch spring 17 for setting the shift torque. That is,
This is because the holding force of the latch spring 17 does not need to be set high, and the effect on the shift torque can be reduced.

As an example of the above-mentioned means, as shown in FIG. 5, by designing the shape of the cam ridge 24 of the elastic body 23 in the trigger 21, the resistance force (F) applied to the elastic body 23 is designed.
The axial component force (F _x ) is high when the trigger 21 is retracted.
(FIG. 5 (a)), it can be set to be low when the trigger 21 returns (FIG. 5 (b)). That is, in FIG. 5, | -F
The shape of the cam ridge 24 is designed so that _x2 | < _Fx1 .

As another embodiment of the speed change mechanism, the locking piece 18 on the speed change torque setting side and the slider 16 may be integrated. That is, the locking piece 18 on the shifting torque setting side is structurally free from collision at the time of shifting or resetting, and there is no need to separate the slider 16 and the locking piece 18 to mitigate the collision.

Further, in order to effectively avoid damage to related parts and the like due to collision between the high-speed side ring gear cam ridge 10 and the high-speed side ring gear locking piece 18 at the time of reset, the high-speed side ring gear cam ridge 10 has a high-speed side. An elastic body 25 for cushioning collision is provided at a contact portion on the side of the ring gear locking piece 18, and is reset when the high-speed ring gear cam peak 10 collides with the high-speed ring gear locking piece 18. Even the elastic body 2
It is also possible to adopt a configuration in which the ring gear 5 is brought into contact with the ring gear cam ridge 10 in advance, and is rotated to a position where the ring gear cam ridge 10 and the locking piece 18 can be securely engaged, and then reset (FIG. 6). However, FIG. 6 is a bottom view ((a) before reset, (b) during reset, and (c) after reset) showing a state change of a portion related to locking before and after reset.

[0026]

As described above, in the invention of the planetary transmission according to the first aspect, at least the sun gear connected to the rotary drive means, the planet gear meshed with the sun gear, and the planet gear coaxial with the sun gear. Has a plurality of planetary mechanisms in the axial direction corresponding to mutually different gear ratios with ring gears meshing with each other, and selects one rotation among the ring gears that are freely rotatable in the planetary mechanism. A selective locking member that can be prevented from moving, and switches the adjacent ring gears engaged with the selective locking member from a low torque high speed side to a high torque low speed side according to a load applied to the ring gear. In a planetary transmission provided with switching means, a latch for latching the selective locking member after a switching operation of the ring gear with which the selective locking member is engaged by the switching means. After the power supply of the rotary driving means is stopped, the rotational kinetic energy due to the inertia of the low-torque high-speed ring gear with which the selective locking member is engaged before the switching operation is sufficiently reduced. Reset means for releasing the latch and returning the selective locking member to an initial state in which the selective locking member is engaged with the low-torque high-speed side ring gear. After stopping, there is an excellent effect that it is possible to eliminate the possibility of shape change, breakage, wear and the like of the related parts due to collision with the low-torque high-speed side ring gear continuing the rotational motion due to inertia.

According to the second aspect of the present invention, in addition to the effect of the first aspect, a smooth change of the ring gear can be surely achieved.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect, the shift operation can be performed automatically and labor-saving by increasing the load. It has an excellent effect.

According to the fourth aspect of the present invention, in addition to the effects of the first to third aspects, after the ring gear is changed, the latch is released by reset means. Until that time,
This provides an excellent effect that an unexpected accident such as breakage or abrasion of related components due to the backward movement of the slider during operation can be prevented.

According to a fifth aspect of the present invention, in addition to the effects of the first to fourth aspects of the present invention, the reset operation is performed without the operator being particularly conscious of the reset operation. It has an excellent effect that it can be performed reliably.

According to the invention of the planetary transmission described in claim 6, in addition to the effect of the invention described in claim 5, the above-mentioned effect can be obtained simply and directly, and the rationalization of the number of parts can be reduced. It has an excellent effect that it can contribute.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment according to the present invention.

FIG. 2 is a bottom view showing a change in a locked state before and after a gear shift according to the embodiment.

FIG. 3 is a diagram showing a relationship between a trigger operation and a transmission mechanism in the embodiment.

FIG. 4 is a diagram showing a relationship between a trigger operation and a speed change mechanism in the embodiment.

FIG. 5 is a diagram illustrating a relationship between a trigger operation and a shape of an elastic body in the trigger according to the embodiment.

FIG. 6 is a bottom view showing a state change of a portion related to locking before and after reset in the embodiment.

FIG. 7 is a diagram showing a relationship between a trigger reset time and a ring gear braking time according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gear case 2 Motor mount 3 Output shaft 4 Sun gear 5 Planetary gear 6 Planetary gear 7 Carrier 8 Ring gear 9 Ring gear 10 Cam mountain 11 Cam mountain 12 Planetary gear 13 Output shaft 14 Ring gear 15 Selection locking member 16 Slider 17 Latch spring DESCRIPTION OF SYMBOLS 18 Locking piece 19 Locking piece 20 Elastic body 21 Trigger 22 Connecting rod 23 Elastic body 24 Cam ridge 25 Elastic body

Continued on the front page F term (reference) 3C036 EE21 3J028 EA01 EA21 EA22 EA28 EB04 EB33 EB35 EB63 FA06 FB03 FC13 FC25 FC62 FD11 GA26

Claims (6)

[Claims] 1. A planetary mechanism having at least a sun gear connected to a rotary driving means, a planetary gear meshing therewith, and a ring gear concentric with the sun gear and meshing with the planetary gear, corresponding to mutually different gear ratios. In the axial direction, a selective locking member that can selectively block one rotation of the ring gear that is freely rotatable in the planetary mechanism is provided, and a load applied to the ring gear is reduced. A planetary gearbox provided with switching means for switching the mutually adjacent ring gears engaged with the selective locking member from a low-torque high-speed side to a high- torque low-speed side. Latch means for latching the selective locking member after the switching operation of the ring gear to be engaged, and switching after the power supply of the rotation driving means is stopped. After the rotational kinetic energy due to the inertia of the low-torque high-speed side ring gear with which the selective locking member was engaged before operation was sufficiently relaxed, the latch was released, and the selective locking member was moved to the low torque. A planetary transmission, comprising: reset means for returning to an initial state engaged with the high-speed side ring gear. 2. The selective locking member has a slider movable at least in the axial direction, and is selectively engageable with only one of the ring gears related to the switching operation adjacent in the axial direction. 2. The planetary transmission according to claim 1, wherein the ring gear to be engaged can be changed by the axial movement of the slider. 3. The switching member according to claim 1, wherein the selective locking member has a shift load torque setting and locking function for one of the ring gears involved in the switching operation adjacent in the axial direction. 3. The ring gear according to claim 1, wherein said ring gear has a locking function.
A planetary transmission as described. 4. The planetary transmission according to claim 1, wherein the latching means prevents the slider from moving in the reverse direction after the switching operation. 5. The resetting means according to claim 1, wherein said resetting means has at least a trigger handle for a power switch, and releases the latch by said latching means by a retracting operation. A planetary transmission according to any of the claims. 6. The planetary transmission according to claim 5, wherein said reset means is linked with said trigger handle by a connecting rod connected to said slider.