Patent ID: 12196290

BEST MODE

The above and other objectives and new features of the present disclosure will become clearer with the description and accompanying drawings of the present specification.

Hereinafter, an embodiment according to the present disclosure will be described according to the accompanying drawings.

FIG.1is a perspective view of a speed reducer having a self-locking function without a ring gear according to the present disclosure, andFIG.2is a perspective view illustrating the configuration of the number of n sets of planetary gears having a straight toothed portion according to the embodiment of the present disclosure.

The speed reducer according to the present disclosure is a speed reducer realized from a high ratio to a low ratio without a ring gear, and as illustrated inFIGS.1and2, includes a carrier200rotated as an input side, a first sun gear300provided concentrically with the carrier200, a first planetary gear500engaged with the first sun gear300, a second planetary gear600engaged with the first planetary gear500, a third planetary gear700engaged with the second planetary gear600, and a second sun gear400concentric with the carrier200, provided in parallel to the first sun gear300, and engaged with the third planetary gear700.

Difference between the number of teeth of the first sun gear300and the number of teeth of the second sun gear400is at least one, the first, second, and third planetary gears500,600, and700are supported at different locations on one side of the carrier200so as to be able to rotate and revolve and be disposed in n sets, and the circumference of teeth of the second planetary gear600is separated from the circumference of each of the first sun gear300and the second sun gear400. Meanwhile, inFIG.2, three sets of the first, second, and third planetary gears500,600, and700are illustrated to be provided, but the configuration of the planetary gears is not limited thereto, and two or at least four sets of planetary gears may be provided.

In the speed reducer according to the present disclosure, as a first type, the carrier200may function as an input side, the first sun gear300may be fixed, and the second sun gear400may function as an output side. In addition, in a planetary gear device according to the present disclosure, as a second type, the carrier200may be the input side, the second sun gear400may be fixed, and the first sun gear300may function as an output side.

In addition, in the speed reducer according to the present disclosure, the first and second sun gears300and400, and the first, second, and third planetary gears500,600, and700may be provided in the same module.

Meanwhile, in the speed reducer according to the present disclosure, the first and second sun gears300and400, and the first, second, and third planetary gears500,600, and700may be provided in the form of any one of an involute tooth, a cycloidal tooth, a straight tooth, and a spiral tooth.

Next, in the speed reducer according to the present disclosure, a gear speed ratio and a self-locking function will be described with reference toFIGS.3and4.

FIG.3ais a cross-sectional view illustrating the gear speed ratio of a first type and a self-locking function according to the embodiment of the present disclosure,FIG.3bis a cross-sectional view taken line V-V according toFIG.3a, andFIG.4ais a cross-sectional view illustrating the gear speed ratio of a second type and a self-locking function according to the embodiment of the present disclosure, andFIG.4bis a cross-sectional view taken line I-I according toFIG.4a.

As illustrated inFIGS.3a,3b,4a, and4b, the speed reducer according to the present disclosure includes the carrier200, the first sun gear300, the second sun gear400, the first planetary gear500, the second planetary gear600, and the third planetary gear700. According to the positions of the input, output, and fixing of the carrier200, the first sun gear300, and the second sun gear400, the gear speed ratio is divided into the gear speed ratios of the first type800illustrated inFIG.3and the second type900illustrated inFIG.4, and according to the number of the teeth of the first sun gear300and the number of the teeth of the second sun gear400, different directions and speeds are output.

As illustrated inFIGS.3aand3b, in the gear speed ratio of the first type800, when the carrier200connected to an input gear190rotates, the first planetary gear500supported on the carrier200rotates the second planetary gear600engaged with the first planetary gear500while rotating and revolving around the first sun gear300coupled to a fixed housing101by a bolt950, the second planetary gear600rotates the third planetary gear700engaged with the second planetary gear600, the third planetary gear700rotates the second sun gear400engaged with the third planetary gear700, so that together with the second sun gear400, a shaft103is rotated to be output. Meanwhile, inFIG.3, reference numeral201refers to a carrier rotation support.

In this case, the third planetary gear700rotates by the same number of teeth as the first planetary gear500, and thus when the carrier200rotates one time, the second sun gear400performs relative rotational motion to the fixed first sun gear300as much as difference in the number of teeth therebetween. The difference in the number of teeth between the number of the teeth of the first sun gear300and the number of the teeth of the second sun gear400is difference in the number of rotations between the input side and the output side. This is the gear speed ratio of the first type800.

The gear speed ratio of the first type800illustrated inFIG.3is expressed as Equation (1-1) below.
R1=Z2/(Z2−Z1)  Equation (1-1)

(Here, R1: a gear speed ratio of the first type, Z1: the number of the teeth of the first sun gear, and Z2: the number of the teeth of the second sun gear)

In the gear speed ratio of the first type800, when the number of the teeth of the second sun gear400is greater than the number of the teeth of the first sun gear300and a value obtained by subtracting the number of the teeth of the first sun gear300from the number of the teeth of the second sun gear400is smaller than the number of the teeth of the first sun gear300, the direction and speed of output are deceleration in the same direction. When the number of the teeth of the second sun gear400is greater than the number of the teeth of the first sun gear300and a value obtained by subtracting the number of the teeth of the second sun gear400from the number of the teeth of the first sun gear300is smaller than the number of the teeth of the second sun gear400, the direction and speed of output is deceleration in a reverse direction.

To summarize the above,when Z1<Z2 and (Z2−Z1)<Z1 are satisfied, an output is decoration in the same direction, andwhen Z1>Z2 and (Z1−Z2)<Z2 are satisfied, an output is deceleration in a reverse direction,

(Here, Z1: the number of teeth of the first sun gear, and Z2: the number of teeth of the second sun gear).

As shown in Table 1 below, in Example 1, when the number of teeth of the first sun gear300is 49 and the number of teeth of the second sun gear400is 50, a gear speed ratio is 50/(50−49)=50/1, and when the input carrier200rotates 50 times, the output of the second sun gear400is one rotation, resulting in a high-ratio deceleration, and deceleration in the same direction in direction and speed.

In addition, in Example 2, when the number of teeth of the first sun gear300is 50 and the number of teeth of the second sun gear400is 26, a gear speed ratio is 26/(26−50)=(−1.08333), and when the input carrier200rotates −1.08333 times, the output of the second sun gear400is one rotation, resulting in a low-ratio deceleration, with a sign “−” meaning a reverse direction, and deceleration in a reverse direction in direction and speed.

The comparison of the examples is shown in Table 1. Table 1 shows the high and low ratios of the first type according to the embodiment of the present disclosure.

TABLE 1First typeExample 1Example 2Z14950Z25026Gear speed ratio R150−1.08333ResultDeceleration inDeceleration in athe same directionreverse directionNoteHigh ratioLow ratio

In Table 1, the sign “−” means that output relative to an input rotation direction is reverse rotation. As can be seen from Table 1, it is easy to see that even if the number of teeth of gears is slightly changed, various gear ratios of high-ratio deceleration and low-ratio deceleration are achieved. Here, when the second sun gear400is changed into an input side and rotated, the second sun gear400rotates the third planetary gear700engaged with the second sun gear400, the third planetary gear700rotates the second planetary gear600engaged with the third planetary gear700, the second planetary gear600rotates the first planetary gear500engaged with the second planetary gear600, and the first planetary gear500rotates the first sun gear300engaged with the first planetary gear500.

In this case, since the first sun gear300is fixed and cannot be rotated, there occurs a phenomenon that the first planetary gear500tries to get out of engagement with the first sun gear300and tries to break away from a support point at which the carrier200supports the first planetary gear500.

However, in this phenomenon, since the first planetary gear500cannot break away from the support point of the carrier200and cannot move away from engagement with the first sun gear300, the first planetary gear500stops rotating on the fixed first sun gear300, and thus the rotating of the first planetary gear500by changing the second sun gear400to the input side is not realized, resulting in a self-locking function of reversal prevention in which a speed increase ratio is zero in the impossible state of speed increase in which the rotating of the first planetary gear500stops.

More specifically, when any one of the first and second sun gears is changed to an input side, the sun gear is in a stationary state in which the sun gear cannot rotate even if the sun gear receives rotation input.

Here, a detailed explanation of reason for which the first planetary gear500does not rotate and power is not transmitted to the input of the second sun gear400is as follows.

The principle of leverage for rotation and revolution of a general planetary gear set is illustrated inFIG.9a.

InFIG.9a, F is force, W is a point of action, A is a fulcrum, and r1 and r2 are distances. The relational expression of the principle of three levers is W×r1=F×r2.

Here, the rotation of the carrier of a general planetary gear set is shown inFIG.9Bbelow.

In the general planetary gear set ofFIG.9b, when a ring gear is fixed and a sun gear is rotated clockwise, a point F inFIG.9bmoves to the right, and the movement of the point F rotates a planetary gear (counterclockwise), and at the same time, the planetary gear decelerates while revolving clockwise concentrically with the circumference of the ring gear.

The revolution of the planetary gear rotates the carrier supported by the planetary gear as illustrated inFIG.9b, and can be found in the principle of a second-class lever. InFIG.9b, an instantaneous rotation center of the planetary gear is a point A, which is the same as a fulcrum point A in the second-class lever, a point F of the planetary gear is the same as a point of force F on the second-class lever, and a point W of the planetary gear is the same as an action point W in the second-class lever.

As the point of force F moves, the action point W moves, and the continuous movement of the action point rotates the carrier. In this case, when the force F is obtained, the force F is doubled since the action point W is the center of the planetary gear according to the relational equation of the principle of the second-class lever, so that the carrier can rotate efficiently with a small force F.

Meanwhile, when the carrier is changed to an input side to increase speed, the principle of third-class lever is applied, the center of the carrier is a force F, a point A is a fulcrum point A, a part at which the planetary gear and the sun gear are engaged with each other is an action point W, so it can be seen that the force F moving the action point W is doubled. When the cases of deceleration and speed increase are compared with each other, it can be seen that a rotational force F is much larger and the action point W is smaller in the case of speed increase than in the case of deceleration.

When applying the interpretation of rotation and revolution in a general speed reducer to the present disclosure, as illustrated inFIG.5, in a case in which the first sun gear300of the present disclosure is fixed and the second sun gear400is changed to an input side to rotate (clockwise), the third planetary gear700and the first planetary gear500rotate counterclockwise as illustrated inFIG.5, and the carrier200by which the first planetary gear500rotating counterclockwise is supported to revolve around the first sun gear300is also rotated counterclockwise.

However, in the gear speed ratio of the first type800of the present disclosure, when the carrier200is an input side, the first sun gear300is a fixed side, the second sun gear400is an output side, Z1 is defined as the number of the teeth of the first sun gear300, Z2 is defined as the number of the teeth of the second sun gear400, and Z1<Z2 and (Z2−Z1)<Z1, the output of the second sun gear is “deceleration in the same direction”, so the clockwise rotation of the carrier200is the clockwise rotation of the second sun gear400.

According to the interpretation of the self-locking principle of the present disclosure, as illustrated inFIG.6, in a case in which the second sun gear400is stationary, as the first sun gear300rotates, the rotation of the first planetary gear500is about to occur. Since the second sun gear400is fixed, a point at which the first planetary gear500and the second sun gear400are engaged with each other is the instantaneous rotation center A, and the tangential force of the first planetary gear500includes a separating tangential force F1 rotating relative to the instantaneous rotation center A and a rotating tangential force F2 engaged with the second planetary gear600.

For example, to obtain the number of rotations of each planetary gear,Z1 is the number of teeth of the first sun gear300,Z2 is the number of teeth of the second sun gear400,Z5 is the number of teeth of the first planetary gear500,Z6 is the number of teeth of the second planetary gear600, Z7 is the number of teeth of the third planetary gear700,when the carrier200rotates one time as an input side, Z1=50, Z2=45, Z5=15, Z6=15, and Z7=15,the number of rotations of the first planetary gear500is 1+(Z2/Z5), which is 4 rotations,the number of rotations of the second planetary gear600is 1−(Z2/Z6), which is (−) 2 rotations,the number of rotations of the third planetary gear700is 1+(Z2/Z7), which is 4 rotations, andthe number of rotation of the first sun gear300is 1−(Z2/Z1), which is 1/10.

Here, when the first sun gear300is rotated in a reverse direction,the first planetary gear500rotates 40 times, which increases speed,the second planetary gear600rotates (−) 20 times, which increase speed, andthe third planetary gear700rotates 40 times, which increases speed.

However, inFIG.6, while a force F1 for the first planetary gear500to break away from the support of the carrier relative to the instantaneous rotation center A is large, the tangential force of F2 becomes a very small rotational force due to increased speed.

Accordingly, the first planetary gear500does not rotate and stops, and the carrier200also does not rotate since the support point of the carrier breaks away from a center thereof and is in a stationary state, so that a self-locking function is performed.

In the gear speed ratio of the second type, as illustrated inFIGS.4aand4b, when the carrier200rotates as an input side, the third planetary gear700supported on the carrier200rotates the second planetary gear600engaged with the third planetary gear700while rotating and revolving around the second sun gear400coupled to a fixed housing cover102by the bolt950, the second planetary gear600rotates the first planetary gear500engaged with the second planetary gear600, the first planetary gear500rotates the first sun gear300engaged with the first planetary gear500, so that together with the first sun gear300, the shaft103is rotated to be output.

In this case, the first planetary gear500rotates by the same number of teeth as the third planetary gear700, and thus when the carrier200rotates one time, the first sun gear300performs relative rotational motion to the fixed second sun gear400as much as difference in the number of teeth therebetween. The difference in the number of teeth between the first sun gear300and the second sun gear400is difference in the number of rotations between input and output. This is the gear speed ratio of the second type900.

The gear speed ratio of the second type900is expressed as Equation (1-2) below.
R2=Z1/(Z1−Z2)  Equation (1-2)

(Here, R2: the gear speed ratio of the second type, Z1: the number of teeth of the first sun gear, and Z2: the number of teeth of the second sun gear)

In the gear speed ratio of the second type900, when the number of the teeth of the first sun gear300is greater than the number of the teeth of the second sun gear400and a value obtained by subtracting the number of the teeth of the second sun gear400from the number of the teeth of the first sun gear300is smaller than the number of the teeth of the second sun gear400, the direction and speed of an output are deceleration in the same direction, but when the number of the teeth of the second sun gear400is greater than the number of the teeth of the first sun gear300and a value obtained by subtracting the number of the teeth of the first sun gear300from the number of the teeth of the second sun gear400is smaller than the number of the teeth of the first sun gear300, the direction and speed of an output are deceleration in a reverse direction. The above is summarized as,when Z1>Z2 and (Z1−Z2)<Z2 are satisfied, an output is deceleration in the same direction, andwhen Z1<Z2 and (Z2−Z1)<Z1 are satisfied, an output is deceleration in a reverse direction(Here, Z1: the number of the teeth of the first sun gear, and Z2: the number of the teeth of the second sun gear).

For example, as shown in Table 2, in Example 5, when the number of the teeth of the first sun gear300is 100 and the number of the teeth of the second sun gear400is 99, a gear speed ratio is 100/(100−99)=100/1, and when the input carrier200rotates 100 times, the output of the first sun gear300is one rotation, resulting in a high-ratio deceleration ratio, and a direction and speed are deceleration in the same direction.

In addition, in Example 6, when the number of the teeth of the first sun gear300is 51 and the number of the teeth of the second sun gear400is 100, a gear speed ratio is 51/(51−100)=(−1.0408), and when the input carrier200rotates −1.0408 times, the output of the first sun gear300is one rotation, resulting in a low-ratio deceleration ratio, and (−) means a reverse direction and a direction and speed are deceleration in a reverse direction.

The comparison of the examples is shown in Table 2. Table 2 shows the examples of high and low ratios of the second type according to the embodiment of the present disclosure.

TABLE 2Second typeExample 5Example 6Z110051Z299100Gear speed ratio R2100−1.0408ResultDeceleration inDeceleration in athe same directionreverse directionNoteHigh ratioLow ratio

In Table 2, the sign “−” means that an output relative to an input rotation direction is reverse rotation.

As can be seen from Table 2 above, it is easy to see that high-ratio deceleration and low-ratio deceleration are achieved even if the number of teeth of gears is slightly changed.

Here, when the first sun gear300is changed to an input side and rotated, the first sun gear300rotates the first planetary gear500engaged with the first sun gear300, the first planetary gear500rotates the second planetary gear600engaged with the first planetary gear500, the second planetary gear600rotates the third planetary gear700engaged with the second planetary gear600, and the third planetary gear700rotates the second sun gear400engaged with the third planetary gear700.

In this case, since the second sun gear400is fixed and cannot be rotated, there occurs a phenomenon that the third planetary gear700tries to get out of engagement with the second sun gear400and tries to break away from a support point at which the carrier200supports the third planetary gear700.

However, in this phenomenon, since the third planetary gear700cannot break away from the support point of the carrier200and cannot move away from engagement with the second sun gear400, the third planetary gear700stops rotating on the fixed second sun gear400, and thus the rotating of the third planetary gear700by changing the first sun gear300to the input side is not realized, resulting in a self-locking function of reversal prevention in which a speed increase ratio is zero in the impossible state of speed increase in which the rotating of the first planetary gear500stops.

More specifically, when any one of the first and second sun gears is changed to an input side, the sun gear is in a stationary state in which the sun gear cannot rotate even if the sun gear receives rotation input.

Here, the self-locking function of reversal prevention in which the third planetary gear700does not rotate and power is not transmitted to the input of the first sun gear300is illustrated inFIG.6, and accordingly, detailed description thereof will be omitted.

In the planetary gear device according to the present disclosure, the above-mentioned gears300,400,500,600, and700can adjust center distances so that both standard gears and front gears can be manufactured without any constraints, and the planetary gear device consists only of external gears, so those skilled in the art can easily manufacture the device. That is, in order to manufacture gears, the number of teeth of each gear is selected, and it is possible to select how many sets of the first, second, and third planetary gears500,600, and700will be arranged at equal intervals. In the speed reducer according to the present disclosure, according to the number of teeth of the first sun gear300and the number of teeth of the second sun gear400, a gear speed ratio is determined, and there is a correlation between the number of the teeth and the number of the sets of the planetary gears arranged at equal intervals. Accordingly, when a value obtained by subtracting the number of the teeth of the second sun gear400from the number of the teeth of the first sun gear300is designated as a multiple of the number n of sets of the planetary gears, the number of teeth of the first sun gear300and the number of teeth of the second sun gear400may be determined as shown in the following Equation (1-3).
Z1−Z2=a multiple ofn(Equation 1-3)

(Here, Z1: the number of teeth of the first sun gear, Z2: the number of teeth of the second sun gear, and n: the number of sets of planetary gears)

In general, when the number Z1 of teeth of the first sun gear300is set as an arbitrary value, the number of planetary gear sets is a multiple of n, and the approximate value of a target gear ratio is searched for and selected in order to arrange n (1, 2, 3, 4, 5) sets of the planetary gears at equal intervals, the number Z2 of teeth of the second sun gear400is determined by Equation (1-3), and the number of teeth of the first, second, and third planetary gears500,600, and700may be freely selected to be the same so that the sets do not overlap.

For example, like the embodiment illustrated inFIG.7, when the number n of sets of planetary gears is 3, the number of teeth of the first sun gear300is randomly set to be 50, the number of teeth of the second sun gear400is selected, n has 3, 6, 9, and 12 as positive multiples, and −3, −6, −9, and −12 as negative multiples according to Equation (1-3).FIG.7is a front view illustrating the arrangement of n sets of planetary gears arranged at equal intervals according to the embodiment of the present disclosure.

Accordingly, when the number of teeth of the second sun gear400is selected on the basis of positive multiples, there are 53, 56, 59, and 62, etc., and when the number of teeth of the second sun gear400is selected on the basis of negative multiples, there are 47, 44, 41, and 38, etc. Among them, the number of teeth suitable for the approximate value of a target gear ratio may be selected.

In the embodiment as illustrated inFIG.7, the number of teeth of the second sun gear400is selected as 41, the number of teeth of a first set of first, second, and third planetary gears500,600, and700is randomly selected as 15, 15, and 21, respectively, since the number of teeth of a second set of first, second, and third planetary gears500,600, and700is required to be the same as the number of teeth of the first set of planetary gears500,600, and700, the number of teeth of a second set of first, second, and third planetary gears500,600, and700is also selected as 15, 15, and 21, respectively, and the number of teeth of a third set of first, second, and third planetary gears500,600, and700may also be selected as 15, 15, and 21, respectively. Here, although the number of teeth of planetary gears may be freely selected as 12, 13 14, 15, . . . 20, 21, . . . 32, and 33, etc., the planetary gears are required to be manufactured without overlapping of gear teeth or engagement with other parts in parts not shown in the embodiment. This is information that anyone skilled in the art can easily understand, and thus will be omitted without being specifically mentioned.

Additionally, for example, when selecting the number of teeth of the first sun gear300after the number n of sets of the first, second, and third planetary gears500,600, and700is 5 and the number of teeth of the second sun gear400is randomly selected as 51, since according to the above Equation (1-3), the positive multiples of 5 sets are equal to 5, 10, and 15, etc., and the negative multiples thereof are equal to −5, −10, and −15, etc., the number of teeth of the first sun gear300is selected as 56, 61, and 66, etc. by applying the positive multiples, and the number of teeth of the first sun gear300is selected as 46, 41, and 36, etc. by applying the negative multiples. Among them, the number of teeth suitable for the approximate value of a target gear ratio may be selected. Even here, the number of teeth of the planetary gears may be freely selected as described above.

Next, the engagement of gears according to the number of planetary gear sets will be described with reference toFIG.8.

FIG.8ais a front view illustrating the arrangement of n sets of planetary gears after changing an intervening angle according to the embodiment of the present disclosure,FIG.8bis a front view illustrating an impossibility of the engagement of gear teeth before changing an intervening angle according to the embodiment of the present disclosure,FIG.8cis a side view illustrating a side according toFIG.8a,FIG.8dis a cross-sectional view taken along line P-P according toFIG.8c,FIG.8eis a cross-sectional view taken along line W-W according toFIG.8c,FIG.8fis a front view illustrating a position of an intervening angle according to the embodiment of the present disclosure. In addition, inFIG.8, A represents a normal position at which gear teeth are engaged with each other, B represents a position at which gear teeth cannot be engaged with each other, and C represents a position at which gear teeth cannot be engaged with each other.

In the embodiment illustrated inFIG.8a, it is illustrated that the number of teeth of the first sun gear300is 50, the number of teeth of the second sun gear400is 49, and the number n of sets of the planetary gears is 3, and gear teeth are exactly engaged with each other between the gears.

Since difference between the number of teeth of the first sun gear300and the number of teeth of the second sun gear400is 1, the number of sets of planetary gears is required to be 1 according to the above Equation (1-3). However, as illustrated inFIGS.8bto8f, when three sets of planetary gears are arranged at equal intervals, there is no problem of engagement of gear teeth in only a position A of the first set as illustrated inFIG.8b, but gear teeth cannot be engaged with each other in a position B of the second set and a position C of the third set and cannot be assembled.

In addition, as described above, when difference in the number of teeth of the sun gears is one, a maximum gear speed ratio is achieved, and when the number of sets of planetary gears is only one, there is no problem at low speed, but in high speed, excessive vibration occurs and durability deteriorates, which inevitably causes problems.

Accordingly, in order to solve the above problems, as in the embodiment illustrated inFIG.8f, in the carrier200, by using “change in an intervening angle” of straight lines connecting between the centers of gears, the number of sets of planetary gears is determined as n regardless of the condition of the above Equation (1-3).

First, as illustrated inFIG.8f, the “change in an intervening angle” is to change an angle between straight lines connecting between the centers of gears at the position of the first set, the position of the second set, or the position of the third set in the carrier200. For example, the “change in an intervening angle” is to change an angle A03 between a straight line connecting between the center of the first planetary gear500and the center of the second planetary gear and a straight line connecting between the center of the third planetary gear and the center of the second planetary gear, relative to the second planetary gear600at the position of the first set.

As illustrated inFIG.8f, the positions of “the intervening angle” are four places of A01, A02, A03, and A04 at the position of the first set, are four places of B01, B02, B03, B04 even at the position of the second set, and are four places of C01, C02, C03, C04 even at the position of the third set. InFIG.8f, A01 is an angle between a straight line connecting between the center of the third planetary gear at the position of the first set and the center of the carrier and a straight line connecting between the center of the first planetary gear at the position of the first set and the center of the carrier, A02 is an angle between a straight line connecting between the center of the carrier and the center of the first planetary gear at the position of the first set and a straight line connecting between the center of the first planetary gear and the center of the second planetary gear, and A03 is an angle between a straight line connecting between the center of the first planetary gear and the center of the second planetary gear at the position of the first set and a straight line connecting between the center of the third planetary gear and the center of the second planetary gear at the position of the first set, and A04 is an angle between a straight line connecting between the center of the third planetary gear at the position of the first set and the center of the carrier and a straight line connecting between the center of the second planetary gear and the center of the third planetary gear at the position of the first set.

In addition, B01 is an angle between a straight line connecting between the center of the third planetary gear at the position of the second set and the center of the carrier and a straight line connecting between the center of the first planetary gear at the position of the second set and the center of the carrier, B02 is an angle between a straight line connecting between the center of the first planetary gear at the position of the second set and the center of the carrier and a straight line connecting between the center of the first planetary gear and the center of the second planetary gear at the position of the second set, B03 is an angle between a straight line connecting between the center of the first planetary gear and the center of the second planetary gear at the position of the second set and a straight line connecting between the center of the third planetary gear and the center of the second planetary gear at the position of the second set, and B04 is an angle between a straight line connecting between the center of the third planetary gear at the position of the second set and the center of the carrier and a straight line connecting between the center of the second planetary gear and the center of the third planetary gear at the position of the second set.

In addition, C01 is an angle between a straight line connecting between the center of the third planetary gear at the position of the third set and the center of the carrier and a straight line connecting between the center of the first planetary gear at the position of the third set and the center of the carrier, CO2 is an angle between a straight line connecting between the center of the first planetary gear at the position of the third set and the center of the carrier and a straight line connecting between the center of the first planetary gear and the center of the second planetary gear at the position of the third set, C03 is an angle between a straight line connecting between the center of the first planetary gear and the center of the second planetary gear at the position of the third set and a straight line connecting between the center of the third planetary gear and the center of the second planetary gear at the position of the third set, and C04 is an angle between a straight line connecting between the center of the third planetary gear at the position of the third set and the center of the carrier and a straight line connecting between the center of the second planetary gear and the center of the third planetary gear at the position of the third set.

Among the sets, at a set at which gear tooth engagement is impossible, the problem of the impossibility of gear tooth engagement can be eliminated by changing one angle of four intervening angles. In addition, regardless of the number of teeth of the first sun gear300and the second sun gear400in the above Equation (1-3), the number of sets of planetary gear may be increased or decreased.

For example, as in the embodiment illustrated inFIG.8b, parts at which gear teeth cannot be engaged with each other are a part B at the position of the second set and a part C at the position of the third set, and accordingly, the problem of the gear tooth disengagement of the part B at the position of the second set may be solved by changing one of the angles of B01, B02, B03, and B04 at the position of the second set inFIG.8f, and the problem of the gear tooth disengagement of the part C at the position of the third set inFIG.8bmay be solved by changing one of the angles of C01, CO2, C03, and C04 at the position of the third set inFIG.8f.

For a specific example of the part C at the position of the third set, when the center of the second planetary gear600at the position of the third set supported by the carrier200is moved in a direction opposite to the center of the carrier200, the second planetary gear600rotates around the first planetary gear500while the angle C03 between the straight line connecting between the center of the first planetary gear500and the center of the second planetary gear600and the straight line connecting between the center of the third planetary gear700and the center of the second planetary gear600is changed, and rotates the third planetary gear700engaged with the second planetary gear600, and thus gear teeth which cannot be engaged with each other are rotated and moved by the thickness of the teeth so as to be engaged with tooth space of each of mating gears.

In “the change in intervening angle”, when the number of sets of planetary gears is n, in the remaining sets except for one set in which gear teeth are exactly engaged with each other, only a part with which gear teeth interfere is changed, and the number of parts that requires “the change in an intervening angle” will be at most n−1. Here, four intervening angles are formed at the positions of the first, second, third sets, respectively, and it has been mentioned in the above description that only one of the four intervening angles in each of the sets is required to be changed.

This is because when one intervening angle is set or changed according to a “trigonometric function” and “second law of cosines”, remaining intervening angles are automatically set or changed.

In the embodiment illustrated inFIGS.8band8e, as for parts at which gear toot engagement is impossible in the part B and the part C, inFIG.8f, the problem of the interference of gear tooth engagement is solved by changing the angles of B02 and CO2. The angle of B02 is changed from 97 degrees before the change of the angle to 95.4 degrees after the change, and the angle of CO2 is changed from 97 degrees before the change of the angle to 98.6 degrees after the change, and accordingly, it can be seen that the problem of the impossibility of gear tooth engagement through “the change in the intervening angles” can be eliminated, and the number of sets of planetary gears can be increased or decreased.

In the embodiment, the change in the intervening angles of B02 and CO2 is not limited to the embodiments, and 97 degrees before the change in the intervening angles and 98.6 degrees and 95.4 degrees after the change in the intervening angles are not limited to the values of the embodiments, but are changed according to the increase or decrease of the number of teeth of the sun gears and the number of sets of planetary gears, and the change of the positions of the planetary gears.

In summary, the technology of the present disclosure relates to the speed reducer having a self-locking function that can realize various gear speed ratios from high-ratio deceleration to low-ratio deceleration without a ring gear, and includes the carrier rotated as an input side, the first sun gear provided concentrically with the carrier, the first planetary gear engaged with the first sun gear, the second planetary gear engaged with the first planetary gear, the third planetary gear engaged with the second planetary gear, and the second sun gear concentric with the carrier, provided in parallel to the first sun gear, and engaged with the third planetary gear. Difference between the number of teeth of the first sun gear and the number of teeth of the second sun gear is at least one, and the first, second, and third planetary gears are supported at different locations on one side of the carrier so as to be able to rotate and revolve and be disposed in n sets, and when fixing any one of the first sun gear and the second sun gear and switching and one remaining sun gear into an input side, speed is not increased due to a self-locking function and a speed increase ratio is zero.

For the implementation of the self-locking function, in a case in which the carrier is an input side, the first sun gear is fixed, the second sun gear is an output side, Z1 is defined as the number of teeth of the first sun gear, Z2 is defined as the number of teeth of the second sun gear,when Z1<Z2 and (Z2−Z1)<Z1 are satisfied, the output of the second sun gear is deceleration in the same direction, butwhen Z1>Z2 and (Z1−Z2)<Z2 are satisfied, the output of the second sun gear is deceleration in a reverse direction, andwhen only one of the above deceleration conditions is satisfied and the second sun gear is rotated by being changed to an input side, speed is not increased due to a self-locking function and a speed increase ratio is zero.

In addition, in a case in which the carrier is input, the second sun gear is fixed, the first sun gear is output, Z1 is defined as the number of teeth of the first sun gear, and Z2 is the number of teeth of the second sun gear,when Z1>Z2 and (Z1−Z2)<Z2 are satisfied, the output of the first sun gear is deceleration in the same direction, butwhen Z1<Z2 and (Z2−Z1)<Z1 are satisfied, the output of the first sun gear is deceleration in a reverse direction, and when only one of the deceleration conditions is satisfied and the first sun gear is rotated by being changed to an input side, speed is not increased due to a self-locking function and a speed increase ratio is zero.

Accordingly, in the speed reducer of the present disclosure in which deceleration is achieved, when an output side is changed to an input side to be used, speed is not increased due to a self-locking function and a speed increase ratio is zero, that is, the speed reducer is in a non-operating state.

As described above, the present disclosure relates to the speed reducer that can realize various gear speed ratios from high-ratio deceleration to low-ratio deceleration and is composed of only external gears without a ring gear so that difficulty in manufacturing is eliminated and space is reduced, thereby reducing manufacturing costs, and enabling mass production due to ease of processing. In addition, the self-locking function of the speed reducer prevents reversal, thereby enabling easy control and various uses.

As described above, it can be known that a basic technical idea of the present disclosure is to provide the speed reducer device having a self-locking function that is realized from a high ratio to a low ratio without a ring gear, and many other modifications are possible to those skilled in the art within the scope of the basic idea of the present disclosure.

DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS

101: Fixed housing102: Fixed housing cover150: Bearing200: Carrier201: Carrier rotation support300: First sun gear400: Second sun gear500: First planetary gear600: Second planetary gear700: Third planetary gear800: First type gear speed ratio900: Second type gear speed ratio950: Bolt