JP3185450B2 - Sealing device for telescopic shaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A sealing device for a telescopic shaft according to the present invention prevents, for example, muddy water from entering the inside of a telescopic portion of a steering shaft incorporated in a telescopic steering device.

[0002]

2. Description of the Related Art For example, in a cab-over type truck or the like, in order to adjust a height position and a front-rear position of a steering wheel in accordance with a physique and a driving posture of a driver, a structure as shown in FIG. A height adjustment device is used. When the position of the steering wheel 1 is adjusted, the lever 2 is operated to fix the fixed bracket 3
, The steering wheel 1 is moved to a desired position. Thereafter, the lever 2 is moved in the reverse direction, and the lifting bracket 4 is fixed to the fixing bracket 3.

The steering wheel 1 is fixed to an upper end of a steering shaft 5, and the steering shaft 5 is rotatably supported inside a steering column 6, and the lifting bracket 4 is attached to the steering column 6. When the lifting bracket 4 is fixed to the fixed bracket 3 as described above, the position of the steering wheel 1 is fixed to the position after the movement adjustment.

[0004] The lower end of the steering shaft 5,
The steering gear (not shown) is connected to the upper end of the input shaft 7 by a telescopic transmission shaft 8. The transmission shaft 8 comprises a spline tube 9 having a female spline groove on the inner peripheral surface and a spline shaft 10 having a male spline groove on the outer peripheral surface which engages with the female spline groove. The upper end of the spline shaft 10 and the lower end of the steering shaft 5 are connected by an upper universal joint 11 to the lower end of the spline tube 9 and the input shaft 7.
Are connected to each other by a lower universal joint 12. When the lower end position of the steering shaft 5 changes with the adjustment of the height position of the steering wheel 1, the displacement is absorbed by the expansion and contraction of the transmission shaft 8.

By the way, the transmission shaft 8 incorporated in the position adjusting device of the steering wheel 1 as described above is installed in a place where muddy water or the like is splashed as the vehicle runs, such as below a driver's seat. Therefore, it is necessary to take measures to prevent muddy water and the like from entering the inside of the spline tube 9 and to prevent rust between the inner peripheral surface of the spline tube 9 and the outer peripheral surface of the spline shaft 10.

For this reason, conventionally, for example, Japanese Utility Model Laid-Open No. 60-26
As described in Japanese Patent Publication No. 328, a seal member is provided at an upper end opening of the spline tube 9 to prevent muddy water or the like from entering the spline tube 9. 8 to 11 show the structure described in this publication.

At the upper end of the spline tube 9,
The metal holding cylinder 13 is fixed with its upper end protruding above the upper end edge of the spline tube 9. An annular seal member 14 made of an elastic material such as rubber is held inside the upper end of the holding cylinder 13. The inner peripheral edge of the seal member 14 is formed in a forked shape, as shown in FIG.
As shown in (1), the outer peripheral surface of the spline shaft 10 is in contact with the entire circumference. This spline shaft 1
The muddy water and the like adhering to the outer peripheral surface of the tube 0 and flowing down along the outer peripheral surface are blocked by the seal member 14 and prevented from entering the spline tube 9.

Since the lower end of the spline tube 9 constituting the transmission shaft 8 is closed, if the upper end opening of the spline tube 9 is closed by the sealing member 14, the expansion and contraction of the transmission shaft 8 will occur. When the spline shaft 10 moves in and out of the spline tube 9, the pressure in the spline tube 9 changes. As a result, there arises a problem that the force required to extend and contract the transmission shaft 8 and the force required to adjust the height position of the steering wheel 1 increase.

Conventionally, in order to solve such a problem, as shown in FIGS. 12 and 13, for example, vent holes 15 for communicating inside and outside of the spline tube 9 are provided in a part of the spline tube 9. I have. Then, a cover 16 is attached on the outer peripheral surface of the spline tube 9 so as to cover the openings of the vents 15, 15, and muddy water or the like enters the spline tube 9 through the vents 15, 15. We are trying to prevent it. Note that a cylindrical gap 17 that is open only below is provided between the inner peripheral surface of the cover 16 and the outer peripheral surface of the spline tube 9.

[0010]

SUMMARY OF THE INVENTION As in the above conventional structure,
If the seal member 14 for preventing muddy water or the like from entering the spline tube 9 and the air supply / discharge vents 15 in the spline tube 9 are provided independently, the spline tube 9 has a vent. The sealing member 14 includes an operation of drilling the holes 15 and 15 and an operation of attaching the cover 16.
Work other than mounting is required. In addition, the cover 16 is required as a part independent of the seal member 14, and the production and management of the part becomes complicated.

The sealing device for a telescopic shaft according to the present invention has been devised in view of the above-mentioned circumstances, and does not require extra work such as drilling of a ventilation hole or parts other than a sealing member such as a cover. In addition, it is possible to reliably prevent the muddy water or the like from entering the spline tube and also prevent the force required for the expansion and contraction of the expansion and contraction shaft from increasing.

[0012]

The sealing device for a telescopic shaft according to the present invention is similar to the conventional sealing device for a telescopic shaft described above.
A scan <br/> spline tube have a female spline grooves on the inner peripheral surface disposed in the vertical direction, has an outer peripheral surface of the male spline groove to be engaged with the female spline grooves, the upper end opening of said spline tube A spline shaft inserted into the spline tube, and elastically fixed to the upper end of the spline tube so as to maintain watertightness between an inner peripheral edge of an upper end opening of the spline tube and an outer peripheral surface of an intermediate portion of the spline shaft. And a sealing member made of a material.

In particular, in the telescopic shaft sealing device of the present invention, a first gap exists between the inner peripheral surface of the spline tube and the outer peripheral surface of the spline shaft.
In addition, the seal member is provided at the upper end of the support tube portion that can be externally fitted and supported on the upper end portion of the spline tube, and protrudes upward from the upper end edge of the spline tube to be diametrically inward. And a bent portion. A second gap is formed between the lower surface of the bent portion and an upper edge of the spline tube, and a third gap is formed between the inner peripheral surface of the support cylinder and the outer peripheral surface of the spline tube. , Each exists. Further, a first seal lip is formed on the inner peripheral surface of the support cylindrical portion so as to close the third gap by bringing the inner peripheral edge into contact with the outer peripheral surface of the spline tube. A second seal lip for making the inner peripheral edge abut on the outer peripheral surface of the spline shaft, and sealing the entire periphery between the inner peripheral edge of the bent portion and the outer peripheral surface of the spline shaft; Are formed. And the first seal lip is compared to the second seal lip,
Rather easily deformed in the direction breaking the seal by pressure changes, strange
It is characterized by allowing the supply and exhaust of air by shaping .

[0014]

The operation of the telescopic shaft sealing device of the present invention configured as described above is as follows. First, when muddy water or the like adhering to the outer peripheral surface of the spline shaft flows down along the outer peripheral surface, the second seal lip blocks the muddy water or the like and prevents the muddy water or the like from entering the spline tube. .

When the air pressure in the spline tube is changed by expanding and contracting the expansion shaft, the first seal lip is deformed, and the space between the spaces existing on both sides of the first seal lip is changed. To allow the supply and exhaust of air. As a result, the inside and outside of the spline tube communicate with each other through the first to third gaps, and air is supplied and discharged into and from the spline tube. The first seal lip is provided in a place where muddy water or the like is hardly applied, and the first seal lip may be deformed by a small pressure difference. Therefore, when the telescopic shaft expands and contracts, the pressure difference between the inside and outside of the spline tube does not increase, and the force required to expand and contract the telescopic shaft does not increase.

[0016]

1 to 4 show an embodiment of the present invention. The telescopic shaft 18 used as the transmission shaft 8 (FIG. 7) of the steering device and the like includes a spline tube 9 having a female spline groove on the inner peripheral surface and a spline shaft 10 having a male spline groove on the outer peripheral surface. 9, and the female and male spline grooves are engaged with each other. A sealing member 19 made of an elastic material such as rubber is externally fitted and fixed to an upper end portion of the spline tube 9, and the sealing member 19 is provided between the inner peripheral edge of the upper end opening of the spline tube 9 and the spline shaft 10. The watertightness between the outer peripheral surface and the outer peripheral surface is maintained.

[0017] As shown in FIG. 2, the depth D ₂₁ of the male splines of the valleys 21 and 21 is slightly greater than the height H ₂₂ of the ridges 22, 22 of the female spline grooves (D _{twenty one}
> And H ₂₂₎ to. Therefore, the first gaps 20 are formed between the valleys 21 and the peaks 22.

The seal member 19 is provided on the upper end of the spline tube 9 and is supported on the upper end of the spline tube 9. The seal member 19 is provided above the upper end of the spline tube 9. And an inward flange-shaped bent portion 24 that is projected inward and is bent inward in the diameter direction. A projection or the like is formed on one or both of the lower surface 24a of the bent portion 24 and the upper edge 9a of the spline tube 9, and the lower surface 24a and the upper edge 9a are in close contact over the entire circumference. There is no. Therefore, a second gap 25 is formed between the lower surface 24a of the bent portion 24 and the upper edge 9a of the spline tube 9.

On the other hand, the support cylinder portion 23 has a cylindrical outer peripheral surface shape and an inner peripheral surface shape formed in a waveform in accordance with the outer peripheral surface of the spline tube 9. However, the height dimension H ₂₆ of the peaks 26, 26 on the inner peripheral surface of the support cylinder 23 is
The depth dimension D ₂₇ of the valleys 27 on the outer peripheral surface of the spline tube 9 is smaller than D ₂₇ . Therefore, a third gap 28 is formed between the inner peripheral surface of the support cylinder 23 and the outer peripheral surface of the spline tube 9.

First seal lips 29, 29 are formed on a portion of the inner peripheral surface of the support cylinder 23 slightly above the lower end edge of the support cylinder 23. According to the shape of the valleys 27, 27 on the outer peripheral surface of the spline shaft 10, each first seal lip 29, 29 formed on the top of the peaks 26, 26 closes the third gaps 28, 28. . The first seal lips 29, 29 are relatively thin and have low rigidity. Therefore, each first seal lip 29,
When a pressure difference occurs between the two sides of the second gap 29, the gap is relatively easily elastically deformed, and the air can freely flow through the third gaps 28, 28.

On the other hand, a second seal lip 30 is formed on the inner peripheral edge of the bent portion 24. The inner peripheral edge of the second seal lip 30 is in contact with the outer peripheral surface of the spline shaft 10 over the entire circumference, similarly to the conventional seal member 14 (see FIG. 10). This second seal lip 30 is a so-called self-sealing type,
The inner peripheral edge is pressed against the outer peripheral surface of the spline shaft 10 by the pressure of the fluid to be sealed. Therefore, the second seal lip 30 is connected to the first seal lip 29
In comparison with the pressure change, the seal is less likely to be deformed in a direction in which the seal can be broken.

The operation of the sealing device for a telescopic shaft according to the present invention configured as described above is as follows. First, when muddy water or the like adhering to the outer peripheral surface of the spline shaft 10 flows down along the outer peripheral surface, as shown in FIG. 3, the second seal lip 30 blocks the muddy water and the like, and Preventing the spline tube 9 from entering. As described above, the second seal lip 30 is called a self-sealing type and has a high sealing ability, so that the entry of the muddy water or the like can be surely prevented.

When the telescopic shaft 18 is expanded and contracted in order to adjust the height position of the steering wheel 1 (FIG. 7),
The air pressure in the spline tube 9 changes. For example, when the steering wheel 1 is lowered and the telescopic shaft 18 is contracted, the pressure in the spline tube 9 increases. This pressure is applied to the upper surface of each first seal lip 29, 29 via the first, second, and third gaps 20, 25, 28, and the first seal lip 2
9 and 29 are elastically deformed downward to separate the inner peripheral edge of each first seal lip 29 and 29 from the bottom surface of the valleys 27 and 27.

As a result, the inside and the outside of the spline tube 9 communicate with each other through the first, second, and third gaps 20, 25, and 28, and the air in the spline tube 9 is discharged. The first seal lips 29, 29 may be deformed by a small pressure difference. Accordingly, the telescopic shaft 18
At the time of contraction, the air is discharged only by slightly increasing the pressure in the spline tube 9. For this reason, the pressure acting on the lower end surface of the spline shaft 10 does not increase so much, and the force required to push the spline shaft 10 into the steering tube 9 to shrink the telescopic shaft 18 may increase. Absent.

Conversely, when the steering wheel 1 is raised and the telescopic shaft 18 is extended, the pressure in the spline tube 9 decreases. As a result, due to the atmospheric pressure applied to the lower surfaces of the first seal lips 29, 29, the first seal lips 29, 29 are elastically deformed upward and the inner peripheral edges of the first seal lips 29, 29 The outside air is introduced into the spline tube 9 with the bottom and the bottoms of the valleys 27 being separated from each other. The first seal lips 29, 29 are provided slightly above the lower end of the support tubular portion 23 in a location where muddy water and the like are hardly applied, so that muddy water and the like are not sucked even when introducing outside air. In this way, even when the telescopic shaft 18 is extended, the pressure drop in the spline tube 9 is low, and the pressure acting on the upper end surface of the spline shaft 10 is not so high, and the telescopic shaft 18 is extended. Therefore, the force required to pull out the spline shaft 10 from the steering tube 9 does not increase.

FIGS. 5 and 6 show a method of fixing the seal member 19 to the spline tube 9. A ridge 31 is formed on the inner peripheral surface of the support cylindrical portion 23 of the seal member 19, and the ridge 31 and a ridge 32 on the outer peripheral surface of the spline tube 9 are formed.
Engagement is made with locking grooves 33, 33 formed on the top of 32. At the time of engagement between the ridge 31 and the locking grooves 33, 33,
A second gap 25 is formed between the lower surface of the bent portion 24 and the upper edge of the spline tube 9.

[0027]

The telescopic shaft sealing device according to the present invention is constructed and operated as described above, so that there is no need for extra work such as drilling a ventilation hole, and other parts other than a sealing member such as a cover. It is possible to reliably prevent muddy water and the like from entering the spline tube, and to prevent the force required for expansion and contraction of the expansion shaft from increasing. Therefore, a high-performance and highly reliable telescopic shaft can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the present invention and corresponds to a portion a of FIG. 7;

FIG. 2 is a cross-sectional view of FIG.

FIG. 3 is a view similar to FIG. 1, showing a state in which ingress of muddy water or the like is prevented.

FIG. 4 is a diagram corresponding to a portion C in FIG. 1, showing the flow of air when the telescopic shaft is contracted.

FIG. 5 is a cross-sectional view taken along the line II of FIG. 2;

FIG. 6 is a cross-sectional view of the hoe of FIG. 5;

FIG. 7 is a longitudinal side view of a steering device incorporating a telescopic shaft.

FIG. 8 is a half vertical sectional side view showing a first example of a telescopic shaft incorporating a conventional sealing device.

FIG. 9 is a sectional view taken along the line F-F in FIG. 8;

FIG. 10 is a sectional view of the tote.

FIG. 11 is an enlarged view of a portion shown in FIG. 8;

FIG. 12 shows a second example of a telescopic shaft incorporating a conventional sealing device.
The half longitudinal section side view which shows an example.

FIG. 13 is a sectional view of the reel in FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Lever 3 Fixed bracket 4 Lifting bracket 5 Steering shaft 6 Steering column 7 Input shaft 8 Transmission shaft 9 Spline tube 9a Upper edge 10 Spline shaft 11 Upper universal joint 12 Lower universal joint 13 Holding cylinder 14 Seal member 15 Vent port 16 Cover 17 gap 18 telescopic shaft 19 sealing member 20 first gap 21 valley 22 ridge 23 support cylinder 24 bent part 24 a lower surface 25 second gap 26 ridge 27 valley 28 third gap 29 first seal 29 Lip 30 second seal lip 31 ridge 32 ridge 33 locking groove

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16D 3/06 F16J 15/32 301

Claims (1)

(57) [Claims] 1. A inner peripheral surface to have a female splines vertically
A spline tube disposed on the outer periphery of the spline tube, the spline shaft being inserted into the spline tube from an upper end opening of the spline tube, and an upper end of the spline tube. And a sealing member made of an elastic material which is fitted and fixed to the outer portion of the spline tube and maintains a watertight state between an inner peripheral edge of an upper end opening of the spline tube and an outer peripheral surface of an intermediate portion of the spline shaft. A first gap exists between the inner peripheral surface of the spline tube and the outer peripheral surface of the spline shaft, and the sealing member
A support tube portion that can be fitted and supported on the upper end portion of the spline tube, and a bent portion provided at the upper end portion of the support tube portion and projecting upward from the upper end edge of the spline tube and bent inward in the diameter direction. A second gap exists between the lower surface of the bent portion and the upper edge of the spline tube, and a third gap exists between the inner peripheral surface of the support cylinder and the outer peripheral surface of the spline tube. There is a gap, and on the inner peripheral surface of the support cylinder portion, a first seal lip that closes the third gap by contacting the inner peripheral edge with the outer peripheral surface of the spline tube is formed, The inner peripheral edge of the bent portion is brought into contact with the outer peripheral surface of the spline shaft, and a second seal is formed over the entire periphery between the inner peripheral edge of the bent portion and the outer peripheral surface of the spline shaft. of Rurippu is formed, the first seal lip than the second sealing lip,
Rather easily deformed in the direction breaking the seal by pressure changes, strange
A sealing device for a telescopic shaft, characterized in that it allows the supply and exhaust of air by shaping .