JPH086754B2 - High torque transmission shaft - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission shaft, and particularly to a high torque transmission shaft such as a rotor-equipped drive shaft used in a vane compressor driven by a large torque in a wide temperature range. To do.

2. Description of the Related Art For example, in a coupling component of a cylindrical member such as a shaft with a rotor used in a vane type compressor and a shaft, a shaft having a small overall weight and required rigidity and strength is manufactured from steel, and a rotor having a large weight is manufactured. If the cylindrical member is manufactured from a lightweight aluminum alloy, it is possible to achieve weight reduction with sufficient mechanical strength. When firmly connecting a steel shaft to an aluminum alloy rotor, shrink fit, cold fit, press fit, spline joint or serration joint are commonly used, but these methods have the following problems. There is a point.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The shrinkage fitting margin is generally 1/1000 to 3/1000. Since the linear expansion coefficient of aluminum alloy is about 1.8 × 10 ^-5 / ℃, the shrink fitting temperature is 60 ~ 170 ℃, but in practice it is usually 100 ~ 150 ℃ higher temperature . 160 ~ 3
At a temperature of 20 ° C., the hardness and strength of the aluminum alloy decrease, and there is a problem that seizure with the shaft is likely to occur.

In the cold-fitting in which the shaft is cooled to cause heat shrinkage, it is necessary to hold the shaft at a temperature of −200 ° C. or less to secure the interference. A shaft with a small mass easily heats up, which makes it difficult to secure a tight margin and is not economical.

When a shaft part having a large axial dimension of fitting is press-fitted into a hole of a cylindrical member made of an aluminum alloy, seizure or scoring (scoring) is likely to occur between the shaft and the cylindrical member, and the caulking part is once formed. Is severely damaged and irreproducible.

Spline processing or serration processing is performed on the inner peripheral surface of the hole of the cylindrical member and the outer peripheral surface of the shaft, and spline connection or serration connection that fits the shaft by inserting it into the hole requires high cost for processing and is economical. Besides, when the axial dimension of the fitting is large, there is a problem that seizure or galling easily occurs between the shaft and the cylindrical member.

In a wide temperature range of −40 to 200 ° C, the shrink fitted or press-fitted shaft with rotor of the vane compressor undergoes large thermal deformation and the fitting part relaxes. The mold compressor cannot be used. Further, if the interference of the shrink fitting process or the press-fitting process is increased, an increasing stress is generated in the cylindrical member due to the fitting, and the cylindrical member may be deformed. In particular, in a cylindrical member having a notch formed, stress concentration may occur after fitting or during use, resulting in breakage.

In the spline connection or the serration connection capable of transmitting a large torque, bending stress and torsion stress concentrate on the bottom of the groove formed in the shaft, and the fatigue strength decreases. Further, there is a problem that grinding powder, which causes abrasion scratches or seizure on the sliding surface, is generated from the clearance formed at the root portion of each tooth, and the sealability is impaired.

It is an object of the present invention to provide a high torque transmission shaft that includes a shaft and a cylindrical member formed of different metal materials, can be used in a wide temperature range, and has high mechanical strength.

Means for Solving the Problems In the high torque transmission shaft according to the present invention, in which the shaft (1) integrally formed of different metals is fitted in the hole formed in the metal cylindrical member (2), the cylindrical member (2) is A first hole (32) and a second hole (42) which communicate with each other and have different inner diameters.
And a third hole (52), and the shaft (1) has a first shaft part (31), a second shaft part (41) and a third shaft part (51) having different outer shapes. The center point (O ₂ ) of the inner diameter of the second hole (42) coincides with the axis of the shaft (1).
And eccentric from the center point (O ₁ ) of the inner diameter of the third hole (52). The inner diameter of the first hole portion (32) is larger than the inner diameter of the second hole portion (42), and the inner diameter of the second hole portion (42) is the third hole portion (52).
Larger than the inner diameter of. First hole (32) of the cylindrical member (2)
With the first shaft part (31) of the shaft (1), the third hole part (52) of the cylindrical member (2), and the third shaft part (5) of the shaft (1).
The fitting part with 1) is fitted by an interference fit.

In the embodiment of the present invention, the fitting portion between the second hole portion (42) of the cylindrical member (2) and the second shaft portion (41) of the shaft (1) is fitted by loose fit. D ₁ is the inner diameter of the first hole (32) of the cylindrical member (2), D ₂ is the inner diameter of the second hole (42) of the cylindrical member (2), and D ₃ is the inner diameter of the cylindrical member (2). 3 holes (52)
Inner diameter, d ₂ is the outer diameter of the second shaft portion (41) of the shaft (1), ΔT
Is the temperature difference between the temperature at the time of joining and the maximum temperature at the time of use, A is the linear expansion coefficient of the cylindrical member (2), and a is the linear expansion coefficient of the shaft (1), the second hole (42) On the other hand, the eccentricity C by which the first hole (32) is eccentric has the following relationship.

ΔT (D ₂ · A−d ₂ · a) <C <(D ₁ −D ₂ ) / 2 D ₁ −2C> D ₂ > D ₃ −2C The cylindrical member (2) is an aluminum alloy and the shaft (1 )
Is steel. The first hole portion (32) and the second portion of the cylindrical member (2)
An annular groove (62) having an inner diameter larger than the inner diameters of the first hole portion (32) and the second hole portion (42) is formed between the first hole portion (32) and the second hole portion (42). An annular groove (72) having an inner diameter larger than the inner diameters of the second hole (42) and the third hole (52) is formed between the second hole (42) and the third hole (52).

Action In the present invention, the first shaft portion (31), the second shaft portion (41) and the third shaft portion (51) of the shaft (1) are respectively connected to the first hole portion (of the cylindrical member (2) ( 32), second hole (42) and third
It is possible to press fit into the hole (52) at the same time and easily fit together. By fitting the three shafts into the corresponding three holes, the press-fitting stroke can be shortened, whereby seizure and galling can be suppressed, and the press-fitting process can be easily performed. In addition, the second shaft (4
1) and the second hole (42) are the cylindrical member (2) and the shaft (1).
Is sufficiently eccentric (C) from the shaft center due to the clearance due to the difference in linear expansion coefficient between the first shaft part (31) and the third shaft part (51) of the shaft (1). Since they are connected to the first hole portion (32) and the third hole portion (52) by an interference fit, respectively, a large load torque can be transmitted in a wide temperature range by the shaft (1) and the cylindrical member (2). It is possible to prevent the circumferential displacement between the cylindrical member (2) and the shaft (1).

Further, there is a clearance fit between the second shaft portion (41) and the second hole portion (42), and against the increase in clearance due to the difference in thermal expansion between the cylindrical member (2) and the shaft (1). Since the amount of eccentricity is sufficiently large, large circumferential circumferential residual stress and stress concentration do not occur in the second hole portion (42) of the cylindrical member (2), and the cylindrical member is cracked and broken during the press-fitting process or during use. Does not occur,
No decrease in fatigue strength occurs. Since the shaft (1) has a large diameter on the power transmission side, the torsional rigidity is high and the diameter of the shaft (1) can be reduced.

The first hole (32) and the second hole (4) of the cylindrical member (2)
Since the annular grooves (62, 72) are formed between the cylindrical member (2) and the second hole (42) and between the second hole (42) and the third hole (52). Since the plastic fluid generated when the () is inserted is accumulated in the annular grooves (62, 72), the plastic fluid does not hinder the press-fitting.

In addition, the first shaft portion (31) and the third shaft portion (51) are smooth surfaces and are an interference fit by press fitting. Like the spline connection or serration connection, the diameter of the shaft (1) is reduced because the generation of grinding powder that causes malfunction during operation, stress concentration that causes destruction, and fatigue strength do not decrease. be able to.

EXAMPLES Examples of high torque transmission shafts according to the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 shows a high torque transmission shaft in which a rotor and a shaft of a vane type compressor are integrally connected. This high torque transmission shaft is formed by fitting a steel shaft 1 to the inner peripheral surface of a cylindrical member 2 made of aluminum alloy. The aluminum alloy forming the cylindrical member 2 is 12% silicon (Si), 4% copper (Cu), 1%
Magnesium (Mg), 5% iron (Fe), and the balance substantially aluminum (Al). At the time of production, a molten metal having the above composition was formed into an alloy powder by air atomization treatment, and the obtained alloy powder was press-formed at a pressure of 4 tons / cm ² using a cold isostatic press, It is formed into a pellet with a diameter of 210 mm and a length of 450 mm. The prepared pellets were preheated to 450 ℃ in high-purity argon gas and heated to almost the same temperature for 2,300
The cylindrical member 2 having an outer diameter of 62 mm and a width of 3.6 mm in which slits were formed at five positions was extruded. Next, the cylindrical member 2 is cut into a length of 54 mm, and after heat treatment of T7 (JIS standard H0001 aluminum and aluminum alloy tempering symbol), the first hole portion 32 with an inner diameter of 18 mm and the inner diameter of 17 mm shown in FIG. The second hole 42 and the third hole 52 having an inner diameter of 16 mm each have a length of 13.5 mm and the second hole 42
Center point O ₂ of the first hole 32 and the third hole 52 of the center point O ₁
Eccentricity C = 0.4 mm (Fig. 6) and machined and finished. An annular groove 62 having an inner diameter larger than the inner diameters of the first hole 32 and the second hole 42 is formed between the first hole 32 and the second hole 42 of the cylindrical member 2. 2 hole 42
The second hole 42 and the third hole 52 are located between the second hole 42 and the third hole 52.
An annular groove 72 having an inner diameter larger than the inner diameter of the is formed.

The shaft 1 was formed by machining SCM420 material, subjecting it to heat treatments such as quenching and tempering, and then polishing the outer periphery. In the fitting portions 1 to 3, as shown in FIG. 5, the dimension of the first shaft portion 31 on the power transmission side (spline side) is made larger than that of the second shaft portion 41, and the first shaft portion 31, The third shaft portion 51 is 1/1000 to 2.10 with respect to the first hole portion 32 and the third hole portion 52 of the cylindrical member 2, respectively.
5/1000 tightened. First shaft portion 31 and third shaft portion 51
Is a smooth surface, which is an interference fit due to press fitting. Second shaft
The fitting gap between the 41 and the second hole 42 is 0.01 mm. Since the diameter of the first shaft portion 31 on the power transmission side is larger than that of the second shaft portion 41 and the diameter of the second shaft portion 41 is larger than that of the third shaft portion 51, the torsional rigidity of the shaft 1 is also high.

When the shaft 1 is press-fitted into the cylindrical member 2 at room temperature, the first shaft portion 3
1, the second shaft portion 41 and the third shaft portion 51 are respectively inserted into the first hole portion 32, the second hole portion 42 and the third hole portion 52, and the fitting portions 3, 4 and 5 are formed. Form. After the integration, 50 samples were subjected to a press-fitting test, but there were no defects during press-fitting such as seizure or galling.

Next, the end surface, the outer peripheral surface and the slit portion of the integrated cylindrical member 2 were subjected to finish processing to obtain a finished product.

D ₁ is the inner diameter of the first hole 32 of the cylindrical member 2, D ₂ is the inner diameter of the second hole 42 of the cylindrical member 2, and D ₃ is the third hole of the cylindrical member 2.
52 is the inner diameter, d ₂ is the outer diameter of the second shaft portion 41 of the shaft 1, ΔT is the temperature difference between the temperature at the time of coupling and the maximum temperature at the time of use, A is the coefficient of linear expansion of the cylindrical member 2, and a is the axis. If the linear expansion coefficient is 1, the eccentricity C
Has the relationship shown in the following formula.

_{ΔT (D 2 · A-d} 2 · a) <C <(D 1 -D 2) / 2 D 1 -2C> D 2> The D ₃ -2C above _{formula, D 1 = 18mm, D 2} = 17mm, D ₃ = 16mm, tightening margin 1 /
Within the range of 1000 to 2.5 / 1000, d ₁ = 18.063mm (Tightening margin: D ₁
X2 / 1000), d ₂ = 16.032mm (Tightening margin: D ₂ x2 / 1000
_{Cases), d2 = 16.99mm, d 3} = 16.032mm ( interference: D3 × 2 /
1000), ΔT = 180 ° C (temperature difference between room temperature 20 ° C at the time of joining and the maximum operating temperature of the compressor 200 ° C), A = 18 × 10 ^-6 / ° C
(Coefficient of linear expansion of aluminum alloy), a = 10 × 10 ^-6 / ℃
(Coefficient of linear expansion of steel). Substituting these numerical examples into the above equation, 0.024 <C <1, 0.026 <C, and the following equation is 18
The relationships of −2C>17> 16−2C, 18> 17 + 2C> 16, and −0.5 <C <0.5 are obtained. Therefore, C = 0.4 mm satisfies this inequality.

As a result of the actual measurement, the completed high torque transmission shaft according to the present invention is
It has been found that it can withstand a driving torque of 30 kg-m or more. Also, after holding the finished product at a temperature of 150 ° C for 200 hours,
It was installed in a compressor and the load test in a liquid compressed state was repeated 60 times, then it was disassembled and the connection state of the cylindrical member 2 and the shaft 1 was inspected. No cracks occurred in the bottom of the slit where the stress was concentrated in the member 2.

In this embodiment, the first shaft portion 31, the second shaft portion 41 and the third shaft portion 31
Since the shaft portion 51 of each of them is simultaneously press-fitted into the first hole portion 32, the second hole portion 42 and the third hole portion 52 of the cylindrical member 2 at room temperature,
Can be easily fitted together. Further, the first hole portion 32, the second hole portion 42, and the third hole portion 52 corresponding to the plurality of shaft portions of the first shaft portion 31, the second shaft portion 41, and the third shaft portion 51. Since it fits into the plurality of hole portions, the press-fitting stroke can be shortened, the occurrence of seizure and galling can be suppressed, and the press-fitting step can be easily performed. Further, the eccentricity is sufficiently larger than the clearance due to the difference in linear expansion coefficient between the cylindrical member 2 and the shaft 1, and the first shaft portion 31 and the third shaft portion 51 are respectively made into the first by an interference fit. Since the shaft portion 1 and the cylindrical member 2 are coupled with the hole portion 32 and the third hole portion 52, a large load torque can be transmitted in a wide temperature range, and at the same time, the cylindrical member 2 and the shaft 1 can be transmitted.
Can be prevented from shifting in the circumferential direction.

Further, since a clearance fit is provided between the second shaft portion 41 and the second hole portion 42, the amount of eccentricity is sufficiently large with respect to the increase in clearance due to the difference in thermal expansion between the cylindrical member 2 and the shaft 1. In the second hole portion 42 of the cylindrical member 2, large circumferential residual stress and stress concentration do not occur, the cylindrical member does not crack or break during the press-fitting process or during use, and the fatigue strength does not decrease. . Since the shaft 1 has a large diameter on the power transmission side, the torsional rigidity is also high, and the diameter of the shaft 1 can be reduced.

Since the annular grooves 62 and 72 are formed between the first hole 32 and the second hole 42 of the cylindrical member 2 and between the second hole 42 and the third hole 52, Since the plastic fluid generated when the shaft 1 is fitted into the cylindrical member 21 is accumulated in the annular grooves 62 and 72, the plastic fluid does not hinder the press-fitting.

The first shaft portion 31 and the third shaft portion 51 are smooth surfaces,
It becomes a tight fit by press fitting. Like spline connection or serration connection, the diameter of the shaft 1 can be reduced because the generation of grinding powder that causes malfunction during operation, stress concentration that causes damage, and fatigue strength do not decrease. it can.

This embodiment of the present invention is not limited to the above embodiment, and can be applied to many aluminum alloy materials. Also,
It can be applied to torque transmission shafts with simple to complex shapes. Further, each axial dimension of the fitting portion can be arbitrarily set according to the required torque.

As described above, the high torque transmission shaft according to the present invention can be used in a wide temperature range and has high mechanical strength, and thus has a long service life. Further, it is possible to achieve weight reduction, and there is no need to perform spline processing or serration processing.

[Brief description of drawings]

1 is a sectional view showing a high torque transmission shaft according to the present invention, FIG. 2 is a perspective view, FIG. 3 is a plan view of a cylindrical member, FIG. 4 is a sectional view of a cylindrical member, and FIG. 6 and 6 are plan views of the hole. 1 ... Shaft, 2 ... Cylindrical member, 3, 4, 5 ... Outer fitting portion, 31 ... First shaft portion, 41 ... Second shaft portion, 51 ...
3rd shaft part, 32 ... 1st hole part, 42 ... 2nd hole part, 52
...... Third hole, C ... Eccentricity,

Claims (5)

[Claims] 1. A high torque transmission shaft in which a shaft integrally formed of a different metal is fitted in a hole formed in a cylindrical member made of metal, wherein the cylindrical member communicates with each other and has a first hole having a different inner diameter. ,
It has a second hole portion and a third hole portion, and the shaft has a first shaft portion, a second shaft portion and a third shaft portion having different outer shapes, and the center of the inner diameter of the second hole portion. The point is the first point that coincides with the axis of the axis.
Eccentric from the center point of the inner diameters of the hole portion and the third hole portion, the inner diameter of the first hole portion is larger than the inner diameter of the second hole portion,
The inner diameter of the hole portion of is larger than the inner diameter of the third hole portion, the fitting portion between the first hole portion of the cylindrical member and the first shaft portion of the shaft, and the third hole portion of the cylindrical member and the first hole portion of the shaft. A high torque transmission shaft, characterized in that the fitting portion of the shaft 3 is fitted by an interference fit. 2. The high torque transmission according to claim 1, wherein a fitting portion between the second hole portion of the cylindrical member and the second shaft portion of the shaft is fitted by a clearance fit. axis. 3. D ₁ is the inner diameter of the first hole of the cylindrical member, D ₂ is the inner diameter of the second hole of the cylindrical member, D ₃ is the inner diameter of the third hole of the cylindrical member, and d ₂ is When the outer diameter of the second shaft portion of the shaft, ΔT is the temperature difference between the temperature at the time of coupling and the maximum temperature at the time of use, A is the linear expansion coefficient of the cylindrical member, and a is the linear expansion coefficient of the shaft, the second The eccentricity C with which the first hole is eccentric with respect to the hole is ΔT (D ₂ · A−d ₂ · a) <C <(D ₁ −D ₂ ) / 2 D ₁ −2C> D ₂ > D ₃ claims a range of -2C first (1) high torque transmission shaft according to claim. 4. The high torque transmission shaft according to claim 1, wherein the cylindrical member is an aluminum alloy and the shaft is steel. 5. An annular groove having an inner diameter larger than the inner diameters of the first hole and the second hole is formed between the first hole and the second hole of the cylindrical member. The annular groove having an inner diameter larger than the inner diameters of the second hole portion and the third hole portion is formed between the hole portion and the third hole portion. High torque transmission shaft.