JPH0783314A - Drive gear - Google Patents

Abstract

PURPOSE:To realize integral formation and increase the rate of meshing by minimizing the transmission loss of drive force. CONSTITUTION:Between a flat gear 1 and an auxiliary flat gear 2, an opening 3 whose diameter is smaller than the value of the smaller one of the tooth root circle diameters of the flat gear 1 and the auxiliary flat gear 2, is formed, and a drive gear G1 is obtained by integral formation. As the opening 3 is formed between both gears 1, 2, the protrusion of the material at the time of integral formation is provided, and the integral formation of the drive gear G1 becomes possible. Also, by the combination of the two gears 1, 2, increasing a meshing rate by restraining the transmission loss of drive force at the minimum becomes possible, too.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive gear for transmitting a driving force.

[0002]

2. Description of the Related Art Examples of conventional drive gears are shown in FIGS.
Are shown respectively.

FIG. 11 shows a spur gear G5, which is a spur gear G5.
The meshing ratio ε _{0 of} is calculated by the following equation.

[0004]

[Equation 1] Where d _K1 : diameter of tip circle on driven side d _K2 : diameter of tip circle on driven side d _g1 : diameter of base circle on driven side d _g2 : diameter of base circle on driven side a: center distance α: pressure angle m: module here Then, assuming that the maximum number of teeth per drive gear of the image forming apparatus is around 120 teeth, the meshing ratio ε ₀ when the pressure angle α is 20 ° is about 1.8, and ε ₀ = 2.0 or more. Can't get

On the other hand, when the pressure angle α is 14.5 °, the limit value of the meshing ratio ε ₀ is about ε ₀ = 2.3, but the sum of the number of teeth of the drive gear and the driven gear is 160 to 180 teeth. Therefore, a large gear ratio cannot be obtained, and there are large design restrictions.

FIG. 12 shows a helical gear G6, and the meshing ratio ε _H of the helical gear G6 is obtained by the following equation.

[0007]

[Equation 2] ε _H = ε ₀ + ε _SP = ε ₀ + btan β / (πm _S ), where ε ₀ : meshing ratio with respect to the front tooth profile (

(Equation 1) ε _SP : Engagement ratio for twisted tooth lines β: Twist angle b: Engagement tooth width m _S : Module at right angles to the axis Thus, in helical gear G6, ε ₀ is already 1.4.
Therefore, it is sufficient to determine the tooth width b and the twist angle β so that ε _SP is 0.6 or more. Actually, ε _H = 2.0 or more can be easily obtained, but depending on the twist angle β, Since the driving force is dispersed in the thrust direction of the rotary shaft, the transmission loss of the driving force is larger than that of the spur gear.

Further, FIG. 13 shows a stepped gear G7,
The stepped gear G7 is composed of two spur gears 21 and 22 in order to make up for the drawbacks of the spur gear.
The meshing ratio is improved by shifting the phases of 22 from each other.

FIG. 14 shows a helical gear G8. The helical gear G8 is composed of two helical gears 31 and 32 in order to make up for the defects of the helical gear. By combining the helical gears 31 and 32 with the opposite twist angles, the thrust force is offset, the transmission loss of the driving force is suppressed to a small level, and the transmission efficiency is improved.

[0010]

However, as shown in FIG.
In the transmission of the driving force using the spur gear G5 shown in (1), there were the following problems in increasing the meshing ratio of the spur gear G5.

(1) When the pressure angle α is set to 20 °, the meshing ratio ε ₀ cannot be set to 1.8 or more in a practical range, so that the normal load when transmitting the driving force fluctuates.

(2) When the pressure angle α is set to 14.5 °,
Although a meshing ratio ε ₀ of 2.0 or more can be obtained, a large gear ratio cannot be obtained due to the restriction of the number of teeth on the driving side and the driven side.

Further, in the transmission of the driving force by the helical gear G6 shown in FIG. 12, there were the following problems in increasing the meshing ratio of the helical gear G6.

(3) When the twist angle β is increased in order to increase the meshing ratio, the driving force dispersed by the twist angle β also increases and the transmission efficiency of the driving force deteriorates.

Further, there were the following problems in manufacturing the step gear G7 shown in FIG. 13 and the helical gear G8 shown in FIG.

(4) One step gear G7 or helical gear G
In order to produce 8, two spur gears 21 and 22 or helical gears 31 and 32 are produced, and both gears 21, 22 or 31, 3
2 needs to be fixed by adhesion, welding, screw tightening, etc., and the processing cost is higher than that of a normal gear.

(5) When the step gear G7 and the helical gear G8 are integrally molded, different gears 21, 22 or 31, 32 are formed.
When the material protrudes from the mating surface of the gear, the accuracy of the gear deteriorates, and the function of the gear that transmits the driving force also deteriorates.

The present invention has been made in view of the above problems. The object of the present invention is to enable integral molding and to minimize the transmission loss of the driving force to increase the engagement rate. To provide a drive gear.

[0019]

In order to achieve the above object, the present invention forms a gap between two gears having a diameter smaller than the smaller value of the diameter of the root circle of these two gears. The feature is that the drive gear is obtained by integral molding.

[0020]

According to the present invention, since the gap is formed between the two gears, it is possible to prevent the material from protruding during the integral molding and to integrally mold the drive gear.

Also, by combining two gears, it is possible to minimize the transmission loss of the driving force and increase the meshing ratio.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a perspective view of a drive gear according to a first embodiment of the present invention.

The drive gear G1 according to the present embodiment is an integrally molded product, which occurs when the spur gear 1 that performs the main drive and the meshing of the teeth of the spur gear 1 move to the next tooth. It is composed of an auxiliary spur gear 2 for suppressing the fluctuation of the normal load, and between the spur gears 1 and 2 is smaller than the smaller value of the root diameter of the spur gears 1 and 2. A gap 3 having a small diameter is formed.

In order to form the driving gear G1, the shape 1'of the spur gear 1 is engraved on one side of the mold 15 as shown in FIG. 2, and the shape 2'of the auxiliary spur gear 2 is likewise not shown. This is carried out by engraving on the surface of the die of, for example, as shown in the figure, on the die 15 side of the spur gear 1, two slide plates 16a, 16b in which the shape 3'of the gap 3 is engraved are provided. By forming the gap 3 with the gear 2 by the slide plates 16a and 16b, it is possible to eliminate the influence of the protrusion of the material from the gears 1 and 2, and it is possible to integrally form the drive gear G1. In FIG. 2, the slide plates 16a, 1
Although the example in which 6b is provided on the mold 15 side of the spur gear 1 is shown, the slide plates 16a and 16b may be provided on the mold side of the auxiliary spur gear 2.

Now, the fluctuation of the normal load in the driving gear G1 will be described with reference to FIGS.

FIG. 3 shows the fluctuation of the normal load applied to the tooth surface per set in an ordinary spur gear. In the figure, the mesh length is a line segment E ₁ E ₂ , and the point E ₁
Positions separated by a normal pitch from the (meshing start point) and the point E ₂ (meshing end point) are points B ₁ and B.
_Set to ₂ .

When the teeth are meshed in the range from point B ₁ to point B ₂ , the adjacent teeth deviate from this mesh and do not actually mesh, and therefore points E ₁ to B
The range between ₂ and point B ₁ to point E ₂ is the meshing range of two sets of teeth.

In the case of such a spur gear, when the normal load on the tooth surface required for transmitting the driving force is P, the normal load P repeats 50% fluctuation as shown in the figure.

On the other hand, FIG. 4 shows the fluctuation of the normal load P applied to the tooth surface per set of the drive gear G1 according to the present embodiment. Since the auxiliary spur gear 2 whose phase is shifted by 1/2 pitch is used, unlike the mechanism of the ordinary spur gear shown in FIG. 3, the auxiliary spur gear 2 is engaged in meshing between points E ₁ and E ₂ of the spur gear 1. meshing of the points E ₁ '~ point E _2' are combined. Therefore,
The driving gear G1 always transmits the driving force by three to four sets of tooth flanks, which results in a variation of the normal load P of about 8
It was suppressed to%.

According to this embodiment, the following effects can be obtained.

(1) Since the substantial meshing ratio of the drive gear G1 is improved, the fluctuation of the normal load is reduced.

(2) Since the drive gear G1 can be integrally molded, the drive gear G1 can be manufactured at the same manufacturing cost as a normal spur gear.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a perspective view of the drive gear G2 according to the present embodiment. In FIG. 5, reference numeral 4 is a spur gear for main driving, and 5 is an auxiliary spur gear for the spur gear 4, which is a module. Is obtained by molding a gear that is an integral multiple of twice or three times as large as the module of the gear 4 in accordance with the phase in which the number of sets in which teeth mesh with each other is largest.

Thus, the drive gear G2 according to the present embodiment is integrally formed in the same manner as the drive gear G1 according to the first embodiment, and the spur gears 4, 5 are located between the spur gears 4, 5. A gap 6 having a diameter smaller than the smaller value of the root circle diameter is formed.

FIG. 6 shows a normal line applied to the tooth surface of one set of the driving gear G2 which is configured by doubling the module of the auxiliary spur gear 5 to that of the spur gear 4 and matching the phase with one tooth jump. This shows the variation of the load P. The basic mechanism of the drive gear G2 is the same as that of the drive gear G1 shown in FIG. 4, but the number of teeth of the spur gear 4 and the auxiliary spur gear 5 must have the above integer value as a common divisor. .

Thus, according to this embodiment, the following effects can be obtained in addition to the effects (1) and (2) in the first embodiment.

(3) Generally, the bending strength of the tooth root is proportional to the module, so the bending strength of the teeth of the auxiliary spur gear 5 is also an integral multiple of the spur gear 4, and the load is the spur gear 4 and the auxiliary spur gear 5.
If evenly distributed, the tooth width of the auxiliary spur gear 5 will be
/ It becomes possible to make it an integer, and it is possible to reduce the total tooth width.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 7 is a perspective view of a drive gear G3 according to the present embodiment. In FIG. 7, reference numeral 7 is a spur gear for main driving, 8 is an auxiliary gear for the spur gear 7, and It is a helical gear made so that the module fits the module at right angles to the axis.

The drive gear G3 according to the present embodiment is also integrally formed in the same manner as the drive gears G1 and G2 according to the first and second embodiments. Gear 7,
A gap 9 having a diameter smaller than the smaller value of the root circle diameter of 8 is formed.

Here, when the drive gear G3 is constituted by the helical gear 8 and the spur gear 7 with the engagement ratio ε ≧ 2.0, the normal load P applied to the tooth surface of each set of the drive gear G3 is P. FIG. 8 shows the fluctuation of Although the basic mechanism of the drive gear G3 is the same as that of the drive gear G1 shown in FIG. 4, according to this embodiment, the following effects can be obtained.

(4) Since the helical gear 8 side can always mesh with two or more sets, the meshing ratio ε ≧ 3.0, so that stable driving force can be transmitted.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. 9 and 10.

FIG. 9 is a perspective view of a drive gear G4 according to this embodiment. The drive gear G4 is composed of helical gears 10 and 11 having the same size but having opposite torsion angles. .

The drive gear G4 according to the present embodiment is integrally molded in the same manner as the drive gears G1, G2 and G3 according to the first to third embodiments, and between the helical gears 10 and 11 is formed. ,
A gap 12 having a diameter smaller than the smaller value of the root diameter of the helical gears 10 and 11 is formed.

Thus, according to the drive gear G4 of this embodiment, the helical gears 10 and 11 have opposite torsion angles, so that as shown in FIG. Thrust forces f ₁ and f ₂ are canceled out by each other.

Therefore, according to this embodiment, the following effect is added to the above (4).

(5) The transmission loss of the driving force due to the thrust force peculiar to the case of using the helical gear can be eliminated.

[0051]

As is apparent from the above description, according to the present invention, a gap having a diameter smaller than the smaller value of the root circle diameter of these two gears is formed between the two gears. Since the drive gear is obtained by integral molding, the drive gear can be integrally molded, and the transmission loss of the driving force can be minimized to increase the meshing ratio.

[Brief description of drawings]

FIG. 1 is a perspective view of a drive gear according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a mold showing a method for molding a drive gear according to the first embodiment of the present invention.

FIG. 3 is a variation diagram of a normal load acting on a tooth surface of a conventional spur gear.

FIG. 4 is a variation diagram of a normal load acting on a tooth surface of the drive gear according to the first embodiment of the present invention.

FIG. 5 is a perspective view of a drive gear according to a second embodiment of the present invention.

FIG. 6 is a variation diagram of a normal load acting on a tooth surface of a drive gear according to a second embodiment of the present invention.

FIG. 7 is a perspective view of a drive gear according to a third embodiment of the present invention.

FIG. 8 is a variation diagram of a normal load acting on a tooth surface of a drive gear according to a third embodiment of the present invention.

FIG. 9 is a perspective view of a drive gear according to a fourth embodiment of the present invention.

FIG. 10 is a vector diagram of thrust force in a drive gear according to a fourth embodiment of the present invention.

FIG. 11 is a perspective view of a conventional spur gear.

FIG. 12 is a perspective view of a conventional helical gear.

FIG. 13 is a perspective view of a conventional stepped gear.

FIG. 14 is a perspective view of a conventional helical gear.

[Explanation of symbols]

 G1 to G4 Drive gears 1, 4, 7 Spur gears 2, 5 Auxiliary spur gears 3, 6, 9, 12 Gap 8 Auxiliary helical gears 10, 11 Helical gears

Front Page Continuation (72) Inventor Toshiyuki Takano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A drive gear which is integrally formed by forming a gap having a diameter smaller than the smaller value of the root diameters of the two gears between the two gears. 2. The drive gear according to claim 1, wherein the two gears are gears which are out of phase with each other in the same module. 3. The two gears are two types of gears, each module having an integral multiple, and the number of teeth of each of which is a common divisor. The drive gear described. 4. The drive gear according to claim 1, wherein the two gears are two types of gears having the same axial right angle module but different twist angles. 5. The drive gear according to claim 1, wherein the two gears are two types of gears having the same helix angle and opposite twist directions.