JP2007002872A - Bearing for supporting steering shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing for supporting a steering shaft capable of preventing uncomfortable noise and vibration from occurring by relieving, at low cost, impact vibration and rattling noise produced while a vehicle travels on a bad road without reducing a bearing clearance in the axial direction. <P>SOLUTION: This bearing for supporting the steering shaft is interposed between a panel 13 partitioning a cabin from an engine room and the steering shaft 2 passed through the panel 13 to rotatably support the steering shaft 2. A grease formed by mixing a lithium soap in a base oil having a viscosity of 1000 mm<SP>2</SP>/sec or higher at 40°C and formed of a poly α-olefinic synthetic oil of 16000 mm<SP>2</SP>/sec or less as an essential ingredient is sealed in the bearing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steering shaft support bearing that is interposed between a panel that partitions a vehicle interior and an engine room and a steering shaft that passes through the panel, and that rotatably supports the steering shaft.

In an automobile steering device, a mechanism as shown in FIG. 5 is used to transmit the movement of the steering wheel to the steering gear.
In FIG. 5, reference numeral 2 denotes a steering shaft. The steering shaft 2 includes an upper steering shaft 2a, an intermediate steering shaft 2b, and a lower steering shaft 2c. The upper steering shaft 2 a is rotatably inserted into the steering column 3, and the steering column 3 is fixed to the instrument 5 via the bracket 4.

A steering wheel 1 is fixed to the projecting end of the upper steering shaft 2 a projecting from the upper end of the steering column 3, and the projecting end of the upper steering shaft 2 a projecting from the lower end of the steering column 3 is intermediately connected via a universal joint 6. A steering shaft 2b is connected.
The intermediate steering shaft 2b is rotatably supported by a panel 13 that partitions the interior of the vehicle and the engine room via a steering shaft support bearing 14, and a lower end portion is connected to the lower steering shaft 2c via a universal joint 7.

The lower end of the lower steering shaft 2c is connected to the input shaft 9 of the steering gear box 10 via the universal joint 8. The steering gear box 10 converts the rotational movement of the steering wheel 1 into the linear movement of the rack, and the left and right tie rods. The left and right knuckles 12 are pushed and pulled through 11 to give a steering angle to the front wheels.
The left and right knuckles 12 are fixed via a knuckle arm (both not shown) connected to a suspension mechanism (both not shown) such as an upper arm, a lower arm and a shock absorber, and incorporated into a wheel. Tires (both not shown).

FIG. 6 shows details of the steering shaft support bearing 14.
In this steering shaft support bearing 14, a plurality of cylindrical rollers 18 as an example of rolling elements are rolled between a metal inner ring 17 and a metal outer ring 20 in a circumferential direction via a synthetic resin cage 19. The cylindrical roller bearings are movably arranged, and rubber seals 21 are attached to both ends in the axial direction.
The intermediate steering shaft 2b is rotatably fitted in the inner ring 17, and the outer ring 20 is fixed to a panel 13 that partitions the engine room and the room.

In the conventional steering shaft support bearing 14 described above, the dimension between the flanges of the inner ring 17 and the outer ring 20 is longer than the axial length of the cylindrical roller 18, and therefore there is a gap in the axial direction. There are radial clearances between the raceways of the inner ring 17 and the outer ring 20, and there is a certain amount of rattling.
By the way, although the load and rotation conditions for the steering shaft support bearing 14 that rotatably supports the intermediate steering shaft 2b are not so severe, vibrations generated during rough road travel are transmitted to the intermediate steering shaft 2b, and the axial direction described above. Due to the presence of the clearance, the cylindrical roller 18 and the flanges of the inner ring 17 and the outer ring 20 may collide, and rattling noise and collision vibration may occur. For this reason, there exists a problem of giving an unpleasant sound and vibration to the driver | operator of a motor vehicle.

Further, if the axial clearance between the cylindrical roller 18 and the inner ring 17 is reduced, collision vibration and rattling noise between the cylindrical roller 18 and the inner ring 17 can be suppressed. In addition, the axial length of the cylindrical roller 18 and the dimensional accuracy between both flange portions of the inner ring 17 need to be increased, and at the same time, the dimensional accuracy and assembly accuracy of each part of the steering need to be increased, resulting in an increase in cost.
The present invention was made in order to eliminate such inconvenience, and without reducing the bearing clearance in the axial direction, mitigating collision vibrations and rattling noises that occur at low cost on rough roads, An object of the present invention is to provide a steering shaft support bearing capable of preventing the generation of unpleasant noise and vibration.

To achieve the above object, the invention according to claim 1 is interposed between a panel that partitions the interior of the vehicle and the engine room and a steering shaft that passes through the panel, and rotatably supports the steering shaft. In steering shaft support bearings,
Viscosity exceeds 1000 mm ² / sec at 40 ° C, equal to or less than 16000mm ² / sec, the base oil and poly-α-olefin-based synthetic oil as an essential component, and wherein the encapsulating grease formulated with lithium soap To do.

The invention according to claim 2 is characterized in that, in claim 1, the thickener contained in the grease is a polymer synthetic oil.
The invention according to claim 3 is characterized in that, in claim 1 or 2, at least the inner ring and the outer ring are made of synthetic resin.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the rolling element is a cylindrical roller.

According to the present invention, beyond the viscosity of 1000 mm ² / sec at 40 ° C, equal to or less than 16000mm ² / sec, the base oil and poly-α-olefin-based synthetic oil as essential components, a grease formulated with lithium soap Since it is sealed, it is possible to mitigate collision vibrations and rattling noises when driving on rough roads at low cost without reducing the bearing clearance in the axial direction, which generates unpleasant sounds and vibrations. Can be prevented.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a steering shaft support bearing as an example of an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a state in which the steering shaft support bearing shown in FIG. 3 is a graph showing the relationship between the axial bearing clearance and the noise level in the present invention example and the conventional example, and FIG. 4 is a graph showing the relationship between the shear rate and the apparent viscosity of the grease in the present invention example and the conventional example. is there.

  As shown in FIG. 1, a steering shaft support bearing 23 as an example of an embodiment of the present invention includes a plurality of cylindrical rollers as rolling elements between an inner ring 27 made of synthetic resin and an outer ring 24 made of synthetic resin. Reference numeral 32 denotes a resin cylindrical roller bearing disposed so as to be able to roll in the circumferential direction through a cage 37 made of synthetic resin, and rubber seals 38 are attached to both ends in the axial direction. Further, flanges 40 are formed at both axial ends of the outer diameter surface of the inner ring 27, and flanges 39 are formed at both axial ends of the inner diameter surface of the outer ring 24.

Here, in this embodiment, the steering shaft support bearing 23, exceeds the viscosity of 1000 mm ² / sec at 40 ° C, equal to or less than 16000mm ² / sec, and poly α olefinic synthetic oil as essential components The base oil is filled with grease containing lithium soap. The base oil of the grease is thickened with a polymer-based synthetic oil, and the apparent viscosity of the grease at a shear rate of 500 s ⁻¹ is 8 Pa · s or more and 100 Pa · s or less.

Next, a steering shaft support bearing 23 having the same structure as that shown in FIG. 1 was attached to the impact acoustic test apparatus 22 shown in FIG.
In this test apparatus 22, an outer ring 24 of a steering shaft support bearing 23 is fitted and fixed to a fixed plate 25 supported by a gantry post 26, and an inner ring 27 is fitted and fixed to an impact shaft 28. A coil spring 29 is attached to the lower end portion of the impact shaft 28, and the spring force of the coil spring 29 can be adjusted by a spring force adjusting spacer 30. The inner ring 27 and the outer ring 24 have clearances in both the axial direction and the radial direction, and the internal clearances of the bearings have positive clearances in both the axial direction and the radial direction.

  A clearance adjusting spacer 36 is fixed to the upper end portion of the impact shaft 28. The gap adjusting spacer 36 rotates the gap adjusting nut 31 provided at the upper end portion of the gantry post 26 to move the impact shaft 28 up and down integrally with the inner ring 27, whereby the axial length of the cylindrical roller 32 is increased. The gap in the axial direction generated by the difference between the dimension between both flanges 39 of the outer ring 24 and the dimension between both collars 40 of the inner ring 27 can be adjusted.

A hemispherical portion 33 is formed at the lowermost end portion of the impact shaft 28, and the hemispherical portion 33 is interlocked with the impact cam 34. The impact cam 34 pushes up the impact shaft 28 as the pulse motor 35 rotates from the minimum diameter, and pushes up the impact shaft 28 by the adjustment gap dimension in the axial direction at the maximum diameter portion.
The impact shaft 28 moves from the maximum diameter to the minimum diameter of the impact cam 34 by the rotation of the impact cam 34, so that the impact shaft 28 suddenly falls downward by the clearance dimension in the axial direction due to the spring force of the coil spring 29. As a result, the cylindrical roller 32 and the flange portion 40 of the inner ring 27 come into contact with each other, and an impact sound is generated. The impact sound at this time was picked up by a sound collecting microphone and measured with a sound level meter.

  The impact test is performed at each point where the clearance in the axial direction is 0.2 mm, 0.4 mm, 0.6 mm, and 0.8 mm (adjusted by the gap adjusting spacer 36). The current product grease shown in Table 1 (conventional example), improved A grease (present invention example 1), and improved B grease (present invention example 2) were used.

FIG. 3 shows the test results.
As can be seen from FIG. 3, when the gap in the axial direction is as small as 0.2 to 0.4 mm, the present invention example 1 using the improved A grease and the present invention example 2 using the improved B grease Although the noise level was reduced by about 20% compared to the conventional example used, the present invention example 1 using the improved A grease is the current product when the gap in the axial direction is relatively large, 0.6 to 0.8 mm. The noise level was reduced by about 10% compared to the conventional example using grease, and the present invention example 2 using the improved B grease was reduced by about 20% compared to the conventional example using the current product grease.
Therefore, Example 2 of the present invention using the improved B grease has a noise suppression effect of about 20% compared to the conventional example using the current product grease without being significantly affected by the gap size in the axial direction. I understand.

  FIG. 4 shows the measurement of the apparent viscosity of each grease. It can be seen that as the shear rate is increased, the apparent viscosity decreases in the order of the current product grease, the improved A grease, and the improved B grease. The reason why the noise suppression effect of the improved B grease does not decrease even when the gap size in the axial direction increases is that the apparent viscosity is hardly changed even when the shear rate is increased, and the damper effect is maintained.

As described above, exceeds the viscosity of 1000 mm ² / sec at 40 ° C, equal to or less than 16000mm ² / sec, the base oil and poly-α-olefin-based synthetic oil as essential components, blended lithium soap, further, the grease Cylindrical rollers can be obtained by encapsulating a base oil in a bearing for supporting a steering shaft by increasing the viscosity of the base oil with a synthetic polymer oil and having an apparent viscosity of 8 Pa · s or more and 100 Pa · s or less. It is produced at low cost when driving on rough roads without reducing the axial gap caused by the difference between the axial length of 32, the dimension between the flanges 39 of the outer ring 24, and the dimension between the flanges 40 of the inner ring 27. It is possible to mitigate collision vibration and rattling noise, thereby preventing generation of unpleasant noise and vibration.

Note that the configurations of the inner ring, the outer ring, the rolling element, and the like of the present invention are not limited to those illustrated in the above embodiment, and can be appropriately changed without departing from the gist of the present invention.
For example, in the above-described embodiment, the case where the present invention is applied to a cylindrical roller bearing as an example of a steering shaft support bearing has been described. Instead, the present invention is applied to a spherical bearing, a ball bearing, or the like. May be.

It is sectional drawing which shows the steering shaft support bearing which is an example of embodiment of this invention. It is sectional drawing which shows the state which attached the steering shaft support bearing which is an example of embodiment of this invention to the impact sound test apparatus. It is a graph which shows the relationship between the bearing clearance of an axial direction, and a noise level in the example of this invention, and a prior art example. It is a graph which shows the relationship between the shear rate of grease in the example of this invention, and a prior art example, and an apparent viscosity. It is explanatory drawing for demonstrating an example of a motor vehicle steering device. It is sectional drawing for demonstrating the conventional steering shaft support bearing.

Explanation of symbols

2 Steering shaft 13 Panel 23 Steering shaft support bearing 24 Outer ring 27 Inner ring 32 Cylindrical roller (rolling element)

Claims (4)

In a steering shaft support bearing that is interposed between a panel that partitions the interior of the vehicle and the engine room, and a steering shaft that passes through the panel, and rotatably supports the steering shaft.
Viscosity exceeds 1000 mm ² / sec at 40 ° C, equal to or less than 16000mm ² / sec, the base oil and poly-α-olefin-based synthetic oil as an essential component, and wherein the encapsulating grease formulated with lithium soap Steering shaft support bearing.   The bearing for supporting a steering shaft according to claim 1, wherein the thickener contained in the grease is a polymer synthetic oil.   The bearing for supporting a steering shaft according to claim 1 or 2, wherein at least the inner ring and the outer ring are made of synthetic resin.   4. The steering shaft support bearing according to claim 1, wherein the rolling element is a cylindrical roller.

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