JP2000230570A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strength, durability and life time without increasing dimension of a universal joint, and to provide the stable torque transmitting function, independently of working angle by setting the offset angle of a ball track within a specified range. SOLUTION: An offset angle ϕT formed by the center OTO of the spherical surface of a guide groove 2b of an outside member 2, a cross point Q of a joint flat surface P and PCD, and a center OTI of the spherical surface of a guide groove 3b of an inside member is set at about 5.5-7.5 degrees. This angle is smaller than that of the conventional one, and depth of the guide grooves 2b, 3b become nearly even in the axial direction in comparison with the conventional one (expressed with a broken line). With this structure, since the depth of a groove is large at shallow parts of the guide grooves 2b, 3b and a contact ellipse is hard to ride over a guide groove shoulder part even under high load conditions, generation of notches in the shoulder part can be prevented, and the strength and durability of the guide grooves 2b, 3b can be improved. Strength and life time of a holder 5 can be improved by forming the holder 5 thick. Furthermore, satisfactory workability is obtained by the offset angle ϕT.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity universal joint used in a power transmission system of an automobile or various industrial machines. More specifically, the present invention relates to a rotating shaft on a driving side and a rotating shaft on a driven side. The present invention relates to a so-called fixed type constant velocity universal joint which does not slide (plunge) in the axial direction, among constant velocity universal joints capable of always transmitting torque smoothly even at such an angle (operating angle).

[0002]

2. Description of the Related Art BJ (Ball Fixed Joint) 1 used in a drive shaft of an automobile is
As shown in FIGS. 2 and 3, the outer ring 2, the inner ring 3, the torque transmission balls 4, and the retainer 5 are provided. A retainer 5 is interposed between the outer ring 2 and the inner ring 3, and the retainer 5 is in spherical contact with the spherical inner peripheral surface 2a of the outer ring 2 and the spherical outer peripheral surface 3a of the inner ring 3, respectively.

The inner peripheral surface 2a of the outer race 2 and the outer peripheral surface 3a of the inner race 3
Are formed with a plurality of curved guide grooves 2b and 3b, respectively.
And the spherical centers of the guide grooves 2b, 3b of the outer ring 2 and the inner ring 3
O_TO, O_TIIs the joint center O (the spherical inner peripheral surface of the outer ring)
2a and the same as the spherical center of the spherical outer peripheral surface 3a of the inner ring)
Are symmetrical with respect to In other words, the spherical center O _TO
And spherical center O_TIIs equidistant from the joint center O in the opposite direction, axial direction
Offset in the direction. For this reason, the guide groove of the outer ring 2
2b and a ball track formed by the guide groove 3b of the inner race 3.
Skewed gradually from one axial direction to the other
It has a wedge shape. Each of the torque transmitting balls 4 has this wedge
Of the outer ring 2 and the inner ring 3
Transfer loads between. Connect all torque transmitting balls 4
Hold on hand plane P (plane perpendicular to bisector of operating angle)
Therefore, the retainer 5 is incorporated.

Since the guide grooves 2b and 3b are offset, when the torque transmitting ball 4 transmits a load,
An axial force acts on each torque transmitting ball 4, and as a result, the torque transmitting ball 4 tends to fly in the direction in which the guide grooves 2b and 3b are opened, that is, in the direction in which the wedge-shaped track space is widened. Along with this, an axial force also acts on the cage 5, and the cage 5 is strongly pressed against the spherical inner peripheral surface 2 a of the outer ring 2 and the spherical outer peripheral surface 3 a of the inner ring 3.

[0005]

As described above, since the guide grooves 2b and 3b have offsets, the depths of the two guide grooves are not uniform in the axial direction. Therefore, when the torque transmitting ball 4 transmits a high load at a shallow portion of the guide groove (when a large operating angle is taken), the contact ellipse due to the contact with the torque transmitting ball 4 increases, and the guide groove shoulder where the stress is concentrated. There is a possibility that the contact ellipse runs over the part and the shoulder is chipped.
As a countermeasure, it is conceivable to reduce the surface pressure by increasing the diameter of the torque transmitting ball 4 or the pitch circle diameter (PCD). However, there is a disadvantage that the outer diameter of the outer ring 2 increases and the constant velocity universal joint increases. Occurs.

Accordingly, an object of the present invention is to provide a small constant velocity universal joint having high strength and excellent in operability and durability.

[0007]

In order to achieve the above object, according to the present invention, the offset angle of the ball track is set at 5.
It was set at 5 ° to 7.5 °.

[0008] Where offset angle φ_TIs shown in Figure 1.
Thus, the spherical center O of the guide groove 2b of the outer member 2_TO, Fitting flat
Intersection Q of plane P and PCD, and guide groove 3 of inner member 3
b spherical center O_TI∠O formed by_TOQO_TIMeans
You. Conventionally, this offset angle φ_TFrom 8.0 to 8.
It is set to about 5 °, but in the present invention, it is smaller than this.
Offset angle φ_TThat is, 5.5 ° ≦ φ_T≦ 7.
5 °.

[0009] Offset angle φ_TFig. 1
As shown in the figure, the depth of the guide grooves 2b and 3b is
It becomes more uniform in the axial direction.
Shown). In this case, when the guide groove is shallow,
As the depth increases, even under high load,
The contact ellipse is difficult to get on, preventing chipping of the shoulder, etc.
To increase the strength and durability of the guide groove
You. Also, since the thickness of the cage can be increased,
Higher strength and longer life of the cage are also achieved. Figure 1 is a guide
The depth of the groove at the shallowest of the grooves 2b and 3b is the same as that of the conventional product.
In this case, the thickness of the cage is
Should be significantly thicker than the conventional cage (indicated by the dashed line).
Can be. Therefore, avoid increasing the size of the constant velocity universal joint.
First, it is possible to improve the load capacity and durability life of the entire joint.
it can.

[0010] On the other hand, if the offset angle is too small,
Conversely, durability and strength are reduced, or operability is a problem
Is a concern.

[0011] Therefore, the desired offset angle φ_TRange
In order to find the BJ, we have to consider the cross-operation, durability and
A test was conducted to compare the quasi-static torsional strength. Cross action
Moves the shaft in the plane containing the opposing ball track.
Bend to maximum working angle, then in a plane perpendicular to the plane
Evaluated by the presence or absence of lock when bending the shaft in the same way
did. In addition, the durability was measured with a load torque of 834 N · m (8
5 kgf), rotation speed: 230 rpm, working angle: 6 °
Quasi-static torsional strength, working angle: 40 °, rotation
Number: 2.5 rpm, increase rate of load torque 0.05 kN
The evaluation was performed under the conditions of m / rev. The test results are shown in FIG.
You. In FIG. 4, x indicates “problem” and Δ indicates “poor”.
, ○ indicates “normal” and ◎ indicates “good” (hereinafter referred to as “good”).
Same in the description below).

[0012] According to FIG. 4, the offset angle is smaller than 5.5 °.
All of cross characteristics, durability and quasi-static torsional strength
And the offset angle is larger than 7.5 °
It can be understood that this is inferior in durability and strength. Follow
Operability, durability, and strength of the constant velocity universal joint
In order to satisfy_TAt least 5.5 °
Is preferably set to 7.5 ° or less.

UJ (Undercut Free Joint)
As for, a test for comparing cruciform operability, durability, and quasi-static torsional strength was performed in the same manner as described above. The test conditions are the same as the BJ test in FIG. 4 except that the quasi-static torsional strength test was performed at an operating angle of 50 °. Offset angle phi _o of the cage is set to 0.9 °.

FIG. 5 shows the test results. As can be seen from the figure, the offset angle φ _T of the ball track is also 5.5 ° in UJ.
As described above, it has been found that the operability, the durability, and the quasi-static torsional strength of the constant velocity universal joint can be simultaneously satisfied by setting the angle to 7.5 ° or less.

[0015] Offset angle φ of UJ cage_CIs 0 °
It is preferable that the angle is larger than 1.5 °.
Offset angle φ exceeding 0 °_CIs the allowable operating angle and cage
Required to ensure the strength of the On the other hand, φ_CBut
If it exceeds 1.5 °, the heat generation will increase significantly,
The depth of the lock is reduced, which in turn leads to a shorter life. here
And the cage offset angle φ_CIs, as shown in FIG.
Spherical center O of outer peripheral surface 5a of cage 5_CO, Joint planes P and P
At the intersection Q of the CD and the spherical surface of the inner peripheral surface 5b of the cage 5
Heart O_CI∠O formed by_COQO_CIMeans Spherical center
O_COAnd spherical center O_CIIs equidistant from the joint center O in the opposite direction.
Offset in the axial direction, and the offset amount is
Ball track spherical center O_TO, O_TIOffset amount
Small.

The outer member is usually manufactured by forging (for example, cold forging), heat-treating (induction hardening, etc.), and then performing finishing (grinding, etc.) for finishing to a predetermined size. According to the present invention, in order to improve the durability of the retainer 5 as described above, any one of the spherical inner peripheral surface 2a and the guide groove 2b of the outer member 2 omits finishing processing such as grinding. It is considered that there is no particular problem in the durability of the entire joint even when used with the forged surface (forged skin).

To verify this, a comparative test was conducted on the effect of the presence or absence of grinding of the inner peripheral portion of the outer member on durability, and the following results were obtained.

[0018]

[Table 1]

As is clear from Table 1, the ball track offset angles φ _T are set to 5.5 ° and 7.5 °, and the inner peripheral portion of the outer member 2 (the spherical inner peripheral surface 2a and the guide groove 2) is set.
b inventions 1 and 2 is omitted grinding both) of any and be compared (comparative product 1 Comparative product 1 and 2 was 8.0 ° offset angle phi _T is there grinding of the inner peripheral portion In Comparative Example 2, the inner peripheral portion was not ground), and improvement in durability was observed. Therefore, when the offset angle phi _T taken in the above range, grinding of the inner peripheral portion of the outer member 2 (on the other hand at least one of the inner circumferential surface 2a and the guide grooves 2b) it becomes optional, costs due to simplification of the working process Down can be achieved.

When the offset angle φ _{T of the} ball track is large, the force (axial force) of the torque transmitting ball 4 trying to fly out in the direction in which the wedge-shaped track space spreads becomes large, and the torque transmitting ball 4 is held. The sound (hitting sound) colliding with the container 5 and the ball track becomes large. Conventionally, the torque transmitting ball 4 is pressed into the pocket 51 of the retainer 5 to form a negative gap between the two, so that the torque transmitting ball 4 is securely held on the joint plane P to reduce the hitting sound. ing. However, when the torque transmitting ball is press-fitted, the torque transmitting ball 4 moves in the pocket 51 of the retainer 5 in a preload state, so that the heat generation and the retainer 5
With wear. Further, since the bending resistance of the constant velocity universal joint is increased, it is difficult to bend manually, and labor may be required when assembling it to a vehicle or the like.

On the other hand, if the offset angle φ _T is made smaller than that of the conventional product, the axial force is weakened, so that it is considered that the interference between the pocket and the torque transmitting ball 4 can be made a positive clearance. .

[0022] Table 2 shows the offset angle φ_TAnd the sound of hits
This is a study of the relationship with the presence or absence of birth.
Just like the offset angle φ_TIs equivalent to the conventional product (φ_T=
(8.0 °) produced a tapping sound,
Cut angle φ_TTo 5.5 °, 6.5 °, or 7.5 °
In the invention products 1 to 3, no hitting sound was observed (compared to the invention).
Both the comparison product and the invention product have the closing margin as a positive gap.
).

[0023]

[Table 2]

[0024] Thus, by setting the offset angle phi _T in the above range, it is possible to interference positive gap between the pockets and the torque transmitting balls even while preventing the occurrence of striking sound. Therefore, it is possible to improve the durability by avoiding heat generation and abrasion of the cage, reduce the bending resistance of the constant velocity universal joint, and improve the assemblability.

[0025] Note that the positive gap here is shown in FIG.
Means a gap in the axial direction, and the width t is 0 μm or more and 25 μm.
m (the gap width in the figure is exaggerated)
Drawing). The circumferential gap may be a negative gap,
To reduce bending resistance, etc.
It is desirable that the positive gap be 25 μm or less.

In order to find a grease suitable for sealing inside the constant velocity universal joint of the present invention, grease having various friction coefficients μ was sealed inside the constant velocity universal joint, and a durability test was performed. The friction coefficient μ of grease was measured using a Savan-type friction and wear tester specified in JIS. Here, as shown in FIG. 7, the Savan-type friction and wear tester has a 1/4 inch steel ball 12 pressed against a rotating ring 11 of 40φ × 4 mm. Rotate at a peripheral speed of 108 m / min and apply a load of 12.7 N (1.3
kgf), and sponge 1
The grease is supplied to the surface of the rotating ring 11 through 3. Then, the movement of the air slide 14 supporting the steel ball 12 is detected by the load cell 15, and the friction coefficient is measured. The measurement of the friction coefficient was performed 10 minutes after the start of the test.

In the durability test, a BJ with a ball track offset angle φ _T = 6.5 ° was used, and a load torque of 834 N
M (85 kgf-m), rotation speed 230 rpm, and operating angle 6 °. Table 3 shows the test results.

[0028]

[Table 3]

From Table 3, it can be seen that a grease having a friction coefficient μ of 0.070 or less, especially a urea thickener, can improve the wear resistance and the durability of the constant velocity universal joint. found.

If a protective layer is provided on the surface of the component parts of the constant velocity universal joint where sliding friction occurs with the mating member, the operability of the constant velocity universal joint can be improved. As an example of the surface portion on which the protective layer is formed, the surface portion of the retainer 5 that is in sliding contact with the outer member 2 or the inner member 3 is exemplified. As the protective layer, a film that is effective for preventing or suppressing metal contact between the base materials, for example, a chemical conversion film such as iron sulfide or an adsorption film such as molybdenum disulfide can be considered. In this case, not only one of the films (for example, a chemical conversion film such as iron sulfide) but also a composite film (a chemical conversion film such as iron sulfide + an adsorption film such as molybdenum disulfide) is formed on the surface. Is also good.

Table 4 compares the influence of the presence or absence of the protective layer on the cruciform operability. The comparative product is still ground and the invention product is coated with molybdenum disulfide. As is clear from Table 4, the operability of the constant velocity universal joint can be further improved by forming the protective layer. The test joint was a BJ having an offset angle φ _T = 6.0 ° for both the comparative product and the invention product.

[0032]

[Table 4]

[0033]

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

As shown in FIGS. 1 to 3, the constant velocity universal joint 1 of this embodiment has a plurality of (usually six) curved guide grooves 2b in the axial direction on the spherical inner peripheral surface 2a. The outer member 2 (outer ring) formed and a plurality of (usually 6)
The inner member 3 (inner ring) in which the curved guide groove 3b of the present invention is formed in the axial direction, and the ball track formed by the guide groove 2b of the outer member 2 and the guide groove 3b of the inner member 3 cooperating with each other. A plurality of (usually six) torque transmitting balls 4 are provided, and a retainer 5 for holding the torque transmitting balls 4.

The center O of the guide groove 2b of the outer member 2_TOAnd inside
Center O of guide groove 3b of member 3_TIMeans with respect to the joint center O
On the opposite side by an equal distance in the axial direction (center O_TOIs the opening of the joint
Side, O _TIIs offset to the back side of the joint). So
Therefore, the ball track has a wide opening side and goes to the back side
Thus, the shape is gradually reduced (wedge shape).

[0036] The spherical center of the outer peripheral surface 5a of the retainer 5, and
The inner peripheral surface 2a of the outer member 2 serving as a guide surface for the outer peripheral surface 5a
All of the spherical centers coincide with the joint center O. In addition,
Center of the spherical surface of the inner peripheral surface 5b of the cage 5, and the inner peripheral surface 5b
What is the center of the spherical surface of the outer peripheral surface 3a of the inner member 3 that becomes the guide surface of
These also coincide with the joint center O. Outer member 2 and inner member 3
Is angularly displaced by the angle θ, the guide guided by the cage 5
The luk transmission ball 4 always has an angle at any operating angle θ.
is maintained in the bisecting plane of θ (θ / 2),
Secured.

[0037] As shown in FIG. 1, the guide groove 2 of the outer member 2
b spherical center O_TO, Intersection Q of joint plane P and PCD,
And the spherical center O of the guide groove 3b of the inner member 3_TIFormed by
Offset angle φ_TIs set between 5.5 ° and 7.5 °
You. This offset angle φ_TIs the offset angle (8
°) and therefore the depth of the guide grooves 2b, 3b
Is more uniform in the axial direction than conventional products (conventional
Product is indicated by a broken line). In this case, in the shallow place of the guide groove,
The groove depth is deeper than the product, so even under high load
It becomes difficult for the contact ellipse to ride on the shoulder of the inner groove, and the shoulder is chipped
To improve the strength and durability of the guide groove.
Can be. Also, the thickness of the cage 5 can be increased.
Therefore, the strength and life of the cage can be increased.
Further, as described above, the offset angle φ within this range_T
If so, the operability is also maintained well.

[0038] Outer member 2, inner member 3, and retainer 5
Is usually subjected to heat treatment such as induction hardening after cold forging.
Then, it is further ground and finished to a predetermined size.
Of these, the spherical inner peripheral surface 2a of the outer member 2 is ground by grinding.
It is used in the condition of forged skin, omitting the work. In the present invention
Is the offset angle φ as described above._TIs smaller than conventional products
Because the durability of the cage 5 is improved due to the
Even if the grinding process of the surface 2a is omitted, a practically sufficient durable life is obtained.
Can be secured. From the same viewpoint, the outer member 2
The grinding of the guide groove 2b may be omitted.
Grinding of both the peripheral surface 2a and the guide groove 2b can be omitted.
Noh.

Further, since the force (axial force) of the torque transmitting ball 4 trying to jump out to the joint opening side is weaker than that of the conventional product, the generation of a hitting sound due to the axial force of the torque transmitting ball 4 can be prevented or prevented. Is suppressed. Therefore, the interference between the pocket 51 and the torque transmission ball 4 can be a positive gap of 0 to 25 μm, and the durability and the heat generation of the retainer 5 can be avoided to further improve the durability. The bending resistance of the universal joint can be reduced, and the assemblability can be improved.

[0040] On the outer peripheral surface 5a and the inner peripheral surface 5b of the retainer 5,
Prevent or suppress metal contact with outer member 2 and inner member 3
In order to achieve this, a chemical conversion film such as iron sulfide or molybdenum disulfide
A protective layer composed of any adsorption film is formed. The protective layer
It only needs to be interposed between the two members that create a pairing sliding contact
In addition to being formed on the retainer 5 side, the outer member 2 side and the inner member
3 side, that is, the inner peripheral surface 2a of the outer member 2 and the inner member 3
May be formed on the outer peripheral surface 3a. Of course, the cage 5 side
And protective layers on both the outer member 2 side and the inner member 3 side.
May be formed.

[0041] The inside of this constant velocity universal joint is
The coefficient of friction μ measured by an abrasion tester is 0.070 or less.
Grease is enclosed.

[0042] FIG. 8 shows an embodiment of the present invention.
9 shows an embodiment applied to a point (UJ). Outside
Spherical center O of guide groove 2b of side member 2_TOAnd plan of inner member 3
Spherical center O of inner groove 3b_TIIs the axial direction with respect to the joint center O
On the other side (O_TOIs the open side of the joint, O_TIIs
Offset to the back of the hand). In addition, cage 5
Center O of the outer peripheral surface 5a_CO(Inner peripheral surface 2a of outer member 2)
And the center of the spherical surface of the inner peripheral surface 5b of the cage 5.
Heart O_CI(Same as the spherical center of the outer peripheral surface of the inner member 3)
Opposite side of the joint center O by the same distance in the axial direction (center O
_COIs the back side of the joint, O_CIIs offset to the opening side of the joint)
Have been. Of the outer peripheral surface 5a and the inner peripheral surface 5b of the cage 5
The offset amount is equal to the offset amount of the guide grooves 2b and 3b.
Is also small.

[0043] Partial area U of guide groove 2b of outer member 2_OYou
And a partial area U of the guide groove 3b of the inner member 3_IIn it
Straight section 2b1, 3 with a straight groove bottom when viewed in vertical section
b1 is formed. The straight part 2b1 of the outer member 2 is
It is formed on one end side of the inner groove 2b (the end on the opening side of the joint),
The straight portion 3b1 of the inner member 3 is at the other end of the guide groove 3b.
(The end on the back side of the joint).

[0044] In this UJ, the BJ shown in FIGS.
Each configuration of the present invention can be applied in the same manner as described above. this
In this case, the specific configuration is common except for the above differences.
Therefore, a duplicate description will be omitted.

[0045]

【The invention's effect】 The constant velocity universal joint according to the present invention is a conventional product.
Higher load capacity
it can. Further, it has excellent durability and can have a long life.
Furthermore, the operability is good, and a stable
It has a function of transmitting torque. In addition, these effects are
This can be realized without increasing the size of the joint.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a constant velocity universal joint (BJ).

FIG. 2 is a longitudinal sectional view of the constant velocity universal joint (BJ), and shows an AA section in FIG. 3;

FIG. 3 is a cross-sectional view of the constant velocity universal joint.

FIG. 4 is a diagram showing test results.

FIG. 5 is a diagram showing test results.

FIG. 6 is an enlarged plan view of the retainer.

FIG. 7 is a sectional view of a Savan-type friction and wear testing machine.

8 is a longitudinal sectional view of the constant velocity universal joint (UJ), and shows a BB section in FIG. 3;

[Explanation of symbols]

 1 Constant velocity universal joint  2 Outer member  2a Inner surface  2b Guide groove  3 Inside member  3a Outer surface  3b Guide groove  4 Torque transmission ball  5 Cage  5a Outer surface  5b Inner surface  2b1 Straight section  3b1 Straight part φ_TBall track offset angle φ_CCage offset angle  O Joint center

Claims (8)

[Claims] An outer member provided with a plurality of axially extending guide grooves on a spherical inner peripheral surface; an inner member provided with a plurality of axially extending guide grooves on a spherical outer peripheral surface; A torque transmission ball disposed on a ball track formed by a pair of guide grooves of an outer member and a guide groove of an inner member; and a torque transmission ball guided by a spherical inner peripheral surface of the outer member and a spherical outer peripheral surface of the inner member. A fixed type constant velocity universal joint comprising a retainer for holding a transmission ball, wherein the spherical center of the guide groove of the outer member and the spherical center of the guide groove of the inner member are axially offset from the joint center in mutually opposite directions. A constant velocity universal joint, wherein the ball track has an offset angle of 5.5 ° to 7.5 °. 2. An outer member provided with a plurality of axially extending guide grooves on a spherical inner peripheral surface, an inner member provided with a plurality of axially extending guide grooves on a spherical outer peripheral surface, A torque transmission ball disposed on a ball track formed by a pair of guide grooves of an outer member and a guide groove of an inner member; and a torque transmission ball guided by a spherical inner peripheral surface of the outer member and a spherical outer peripheral surface of the inner member. A cage for holding the transmission ball, wherein the center of the spherical surface of the guide groove of the outer member and the center of the spherical surface of the guide groove of the inner member are axially offset from the joint center in mutually opposite directions, and the outer peripheral surface of the cage. And a constant-velocity universal joint in which the center of the spherical surface of the inner peripheral surface is axially offset from the center of the joint in the opposite direction to each other, and the guide grooves of the outer member and the inner member are provided with straight portions having linear groove bottoms. In the vault Constant velocity universal joint, characterized in that the offset angle of the click to 5.5 ° to 7.5 °. 3. The constant velocity universal joint according to claim 2, wherein the offset angle of the retainer is greater than 0 ° and 1.5 ° or less. 4. The constant velocity universal joint according to claim 1, wherein at least one of the spherical inner peripheral surface and the guide groove of the outer member is a forged surface. 5. The constant velocity universal joint according to claim 1, wherein the interference between the pocket for accommodating the torque transmitting ball and the torque transmitting ball in the retainer is a positive gap. 6. The constant velocity universal joint according to claim 5, wherein the positive gap is 0 to 25 μm. 7. The constant velocity universal joint according to claim 1, wherein a grease having a friction coefficient of 0.070 or less is sealed therein. 8. The constant velocity universal joint according to claim 1, wherein a protective layer is provided on a surface portion of the constituent members of the constant velocity universal joint that causes sliding friction with a counterpart member.