JP7736231B2 - Strut bearing device and strut suspension for vehicle - Google Patents

Description

The present invention relates to a strut bearing device used in a strut-type suspension for a vehicle.

Strut suspensions are suspensions that use coil springs to support the wheels against the vehicle body and are equipped with shock absorbers to absorb vertical vibrations. These suspensions have an expandable strut attached to the axle, incorporating a shock absorber. Strut suspensions are widely used, primarily for the front wheels of passenger cars.

A strut bearing device used in the upper part of a strut suspension has an upper case made of synthetic resin that holds the upper raceway (e.g., upper cap 3 in Patent Document 1), a lower case made of synthetic resin that holds the lower raceway (e.g., lower cap 4 in Patent Document 1), and an inner diameter side seal material (e.g., inner seal 6 in Patent Document 1) and an outer diameter side seal material (e.g., outer seal 7 in Patent Document 1) made of elastomer attached to the lower case (see, for example, Patent Document 1).

U.S. Patent No. 10,753,389

Such strut bearing devices are used in harsh muddy environments, where they are directly exposed to muddy water from the road surface that is kicked up by the wheels. Furthermore, when a high-pressure washer is used to wash the car, the strut bearing device is exposed to the high-pressure water released from the washer when washing the undercarriage.

Therefore, for example, in the strut bearing device of Patent Document 1, if high-speed water such as muddy water enters the gap between the upper cap 3 and the lower cap 4 from the outer diameter side, the water will rise along the outer surface of the lower cap 4 and will not be sufficiently decelerated, causing the outer seal 7 to become wet, which could reduce sealing performance.

Furthermore, if a labyrinth structure is used to slow down the high-speed water that seeps in through the gaps, the structure becomes more complex and the ability to drain muddy water and other liquids that have already seeped inside becomes poor.

The objective of the present invention is to provide a strut bearing device that prevents a decrease in sealing performance while maintaining drainage of muddy water and other liquids that have entered the device.

The gist of the present invention is as follows:

[1]
A strut bearing device including a strut bearing and an upper spring seat which is a spring support component that supports an upper end of a coil spring,
The strut bearing is
an upper case and a lower case;
an upper raceway ring held by the upper case;
a lower raceway held by the lower case;
a rolling element that rolls between the upper raceway ring and the lower raceway ring;
a seal positioned radially outward of the rolling element;
Equipped with
The upper spring seat contacts the lower case,
an outer diameter side recess formed by the lower case and the upper spring seat, the outer diameter side recess being stepped down radially inward from the outer diameter side recess, the outer diameter side recess being formed by the lower case and the upper spring seat, the inner diameter side recess being stepped down radially inward from the outer diameter side recess,
The inner diameter recess receives muddy water or the like that has infiltrated radially inward from the axial gap.
Strut bearing assembly.

[ 2 ]
The radial length of the inner diameter side recess is equal to or greater than the axial gap,
The position of the upper end of the inlet of the inner diameter side recess is higher than the position of the upper end of the axial gap.
The strut bearing device according to [1].

[ 3 ]
A strut suspension for a vehicle equipped with the strut bearing device of [1] or [2].

The strut bearing device and vehicle strut suspension according to the present invention described above have an outer diameter recess located radially inward of the axial gap between the upper case and the upper spring seat, or radially inward of the axial gap between the upper case and the lower case, and an inner diameter recess stepped radially inward from the outer diameter recess. The inner diameter recess receives muddy water and the like that seeps radially inward from the axial gap.

When high-speed water, such as muddy water, enters through the axial gap, the high-speed water first enters the inner diameter recess located radially inward of the axial gap, passes through the outer diameter recess, and approaches the outer diameter seal. Therefore, the high-speed water is initially received by the inner diameter recess and significantly slowed down, and then further slowed down in the outer diameter recess before approaching the outer diameter seal, thereby preventing a deterioration in the sealing performance of the outer diameter seal.

Furthermore, since there is no labyrinth structure and only the outer diameter recess and the inner diameter recess are provided, the structure is not complicated and can be simplified, and the drainage of muddy water and other liquids that have entered the interior is not impaired.

1 is a schematic partial cross-sectional view of a strut suspension for a vehicle equipped with a strut bearing device according to a first embodiment of the present invention; FIG. 2 is an enlarged longitudinal cross-sectional view of a main portion showing the strut bearing device and an upper insulator. FIG. 3 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a first modified example. FIG. 10 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a second modified example. FIG. 10 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a third modified example. FIG. 10 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a fourth modified example. FIG. 10 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a fifth modified example. FIG. 10 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a sixth modified example. FIG. 13 is an enlarged longitudinal sectional view of a main part similar to FIG. 2, showing a seventh modified example. 10 is an enlarged longitudinal cross-sectional view of a main portion showing an example of changes in the flow rate of water that has entered through an axial gap in a strut bearing device having an outer diameter recess and an inner diameter recess. FIG. FIG. 10 is an enlarged longitudinal cross-sectional view of a main portion showing an example of changes in the flow rate of water that has entered through an axial gap in a conventional strut bearing device. FIG. 10 is a diagram showing the analysis results of the flow velocity of water that has infiltrated through an axial gap in an example of an analytical model of a strut bearing device having an outer diameter recess and an inner diameter recess. FIG. 6 is an enlarged longitudinal cross-sectional view of a main portion showing a strut bearing device according to a second embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings.

In this specification, the direction parallel to the rotation axis O (see Figure 1) of the strut bearing 1 is referred to as the "axial direction" (see, for example, arrow J in Figure 1), the direction perpendicular to the rotation axis O is referred to as the "radial direction" (see, for example, arrow R in Figure 1), the radial direction approaching the rotation axis O is referred to as the "radially inward direction" (see, for example, arrow RI in Figure 1), and the radial direction moving away from the rotation axis O is referred to as the "radially outward direction" (see, for example, arrow RO in Figure 1).

[First Embodiment]
<Strut suspension>
The strut suspension S of a vehicle shown in the partial cross-sectional schematic diagram of FIG. 1 is used with an expandable strut 10 incorporating a shock absorber fixed to an axle (not shown) and an upper mount 16 fixed to the vehicle body.

The upper part of the strut suspension S is equipped with a strut bearing 1 that supports the vehicle body and oscillates and rotates as the direction of the steered wheels changes due to steering operation. The oscillating angle of the strut bearing 1 is determined according to the allowable steering angle of the wheels, and is set, for example, in the range of 40° to 50°.

The strut 10 is fitted radially outward (RO) with a coil spring 11, which serves as a suspension spring, and a dust boot 12, which protects the shock absorber's oil seal from sand and other foreign objects. The strut suspension S includes a spring support component 13 that supports the upper end of the coil spring 11. As shown in the enlarged longitudinal cross-sectional view of a key portion of Figure 2, the spring support component 13 consists of an upper spring seat 14 and an upper insulator 15.

<Strut bearing device>
As shown in the schematic diagram of FIG. 1 and the longitudinal cross-sectional view of FIG. 2, a strut bearing device A according to a first embodiment of the present invention includes a strut bearing 1 and an upper spring seat 14, which is a spring support component 13 that supports the upper end of a coil spring 11.

The strut bearing 1 comprises an upper case 2, a lower case 3, an upper raceway ring 4, an upper raceway ring 5, rolling elements 6, a cage 7, an inner diameter seal 8, an outer diameter seal 9, etc.

The upper case 2 is fixed to the upper end of the strut 10, and the lower case 3 receives the upper spring seat 14 from above. The upper raceway 4 is held in the upper case 2, and the lower raceway 5 is held in the lower case 3. The rolling elements 6 roll between the upper raceway 4 and the lower raceway 5, and the cage 7 holds the rolling elements 6 so that they do not come into contact with each other.

The inner diameter seal 8 is located radially inward RI of the rolling element 6, and the outer diameter seal 9 is located radially outward RO of the rolling element 6.

The upper and lower raceways 4, 5, and upper spring seats 14 are made of steel and are formed by pressing steel plates, then quench-hardened after processing. The upper and lower cases 2, 3 are made of synthetic resin, and the inner seal 8 and outer seal 9 are made of elastomer.

The synthetic resin used for the upper case 2 and lower case 3 is, for example, a polyamide-based resin (PA66, PA46, PA612, PA6, PA9T, PA10T, etc.), and contains 20 to 60% by weight of glass fiber (GF) as a reinforcing fiber.

The elastomers used for the inner seal 8 and outer seal 9 are thermoplastic elastomers (TPE), such as TPS (styrene-based), TPO (olefin-based), TPU (urethane-based), TPA (amide-based), and TPEE (ester-based), while rubber materials include nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), ethylene acrylic rubber (AEM), fluororubber (FKM, FPM), and silicone rubber (VQM). One type of rubber material can be used, or two or more types can be blended together.

<Outer diameter side recess and inner diameter side recess>
2, strut bearing device A has an outer diameter side recess DO formed by the lower case 3 and upper spring seat 14, and an inner diameter side recess DI stepped radially inward from the outer diameter side recess DO, at a radially inward side RI of an axial gap C1 between the upper case 2 and upper spring seat 14. The inner diameter side recess DI receives muddy water and the like that seeps into the radially inward side RI from the axial gap C1.

The inner diameter recess DI in Figure 2 is annular, and the longitudinal cross section of the inner diameter recess DI along the radial direction R is approximately triangular. The upper surface of the inner diameter recess DI is a substantially horizontal surface formed by the lower case 3, and the lower surface of the inner diameter recess DI is a slope formed by the upper spring seat 14 that rises radially inward RI.

The inner diameter side recess DI may have the shape of a first modified example shown in the enlarged longitudinal cross-sectional view of a main portion of FIG. 3, the shape of a second modified example shown in the enlarged longitudinal cross-sectional view of a main portion of FIG. 4, the shape of a third modified example shown in the enlarged longitudinal cross-sectional view of a main portion of FIG. 5, the shape of a fourth modified example shown in the enlarged longitudinal cross-sectional view of a main portion of FIG. 6, the shape of a fifth modified example shown in the enlarged longitudinal cross-sectional view of a main portion of FIG. 7, or the shape of a sixth modified example shown in the enlarged longitudinal cross-sectional view of a main portion of FIG. 8. The inner diameter side recesses DI shown in FIGS. 3 to 8 are all connected in an annular shape, similar to the inner diameter side recess DI shown in FIG. 2.

The inner diameter side recess DI of FIG. 3, which is a first modified example, has a generally triangular cross section along the radial direction R, similar to the inner diameter side recess DI of FIG. 2, but the upper surface of the inner diameter side recess DI is an inclined surface that slopes downward in the radially inward direction RI, and the lower surface of the inner diameter side recess DI is generally horizontal. The inner diameter side recess DI of FIG. 4, which is a second modified example, has a generally rectangular cross section along the radial direction R of the inner diameter side recess DI, and the upper and lower surfaces of the inner diameter side recess DI are generally horizontal. The inner diameter side recess DI of FIG. 5, which is a third modified example, has a generally trapezoidal cross section along the radial direction R of the inner diameter side recess DI, the outer diameter side portion of the upper surface of the inner diameter side recess DI is an inclined surface that slopes downward in the radially inward direction RI, and the lower surface of the inner diameter side recess DI is generally horizontal.

The inner diameter side recess DI of the fourth modified example shown in Figure 6 has a cross section along the radial direction R of the inner diameter side recess DI that is approximately parallelogram-shaped, and the upper and lower surfaces of the inner diameter side recess DI are inclined surfaces that rise inward in the radial direction RI. The inner diameter side recess DI of the fifth modified example shown in Figure 7 has an outer diameter side portion of the inner diameter side recess DI that is approximately parallelogram-shaped like the fourth modified example (Figure 6), and an inner diameter side portion of the inner diameter side recess DI that is approximately rectangular like the second modified example (Figure 4). The inner diameter side recess DI of the sixth modified example shown in Figure 8 has a shape in which the inner diameter side portion of the inner diameter side recess DI of the fourth modified example (Figure 6) is extended upward so that the cross section along the radial direction R is approximately rectangular.

The inner diameter recess DI may have a shape different from that shown in the enlarged longitudinal cross-sectional views of essential parts in Figures 2 to 8, and it does not have to be a circular, circumferentially connected shape.

The depth H (length in the radial direction R) of the inner diameter recess DI shown in Figures 2 to 8 is set to be equal to or greater than the axial clearance C1 (H≧C1), and the position F of the upper end of the inlet of the inner diameter recess DI is set higher than the position G of the upper end of the axial clearance C1. This makes it easier for high-speed water that has entered through the axial clearance C1 to enter the inner diameter recess DI and also makes it easier for the high-speed water to decelerate.

By raising position F of the upper entrance end of the inner diameter recess DI higher than position G, in the examples shown in Figures 2 and 6-8, the axial length L of the entrance of the inner diameter recess DI is equal to or greater than the axial clearance C1 (L≧C1). In the examples shown in Figures 3-5, the axial length L is greater than the axial clearance C1 (L>C1). Furthermore, based on the analysis results shown below, it is more preferable to set L≦2.0×C1. Furthermore, based on the analysis results shown below, it is more preferable to set the radial length H of the inner diameter recess DI to H≧2.5×C1. The inner diameter end of the inner diameter recess DI is positioned radially outward RO from the pitch circle diameter of the rolling elements 6 to suppress deformation of the lower case 3 due to the load received from the rolling elements 6.

In the first embodiment shown in Figures 2 to 8, the upper case 2 has an annular inner protrusion K at its lower end on the radially outward side RO that protrudes radially inward RI. The inner protrusions K are arranged intermittently, with one or more located around the circumference. The inner protrusions K engage with outer diameter recesses DO to prevent separation between the upper case 2 and the lower case 3. In the strut bearing device A of the first embodiment, the inner protrusion K may be eliminated, as in the seventh modified example shown in the enlarged longitudinal cross-sectional view of a key portion of Figure 9. In that case, a separation prevention structure (not shown) may be provided on the inner diameter side.

<Comparison of flow speed of infiltrating muddy water with and without inner diameter recess>
(Analysis model)
A comparison was made between the flow velocity of water that entered through the axial gap C1 below the outer seal 9 and the presence or absence of the inner recess DI of the shape shown in Figure 2. That is, analytical models were created and the comparison was made using fluid analysis. The analytical model with the outer recess DO and the inner recess DI imitated the shape shown in Figure 2. The analytical model without the inner recess DI imitated the shape shown in Figure 2, with the outer peripheral surface of the lower case 3 of Figure 2 positioned at the position of the imaginary line I, and had a recess D of the shape shown in Figure 11.

(Analysis conditions)
To simplify the analysis, an underwater environment was used. The position in the radial direction R from which water is ejected was the position where the nozzle contacts the outer diameter of the upper spring seat 14 (see Figure 1), and the position in the axial direction J from which water is ejected was the position where the bottom end of the nozzle contacts the top end of the outer diameter of the upper spring seat 14. The analysis was performed under conditions where the diameter of the nozzle was 2 mm and water was ejected from the nozzle at a high speed with a flow rate of 8 m/s.

In the analytical model with an outer diameter side recess DO and an inner diameter side recess DI, the axial clearance C1 shown in Figures 2 and 10 was set to 1.0 mm, the radial length H of the inner diameter side recess DI was set to 2.5 mm (H = 2.5 x C1), the axial length of the entrance of the inner diameter side recess DI was set to L = 2.0 mm (L = 2.0 x C1), the radial length M of the outer diameter side recess DO shown in Figure 10 was set to 2.0 mm, and the axial distance P between the end of the outer diameter side recess DO on the outer diameter side seal 9 side and the upper spring seat 14 was set to 3.0 mm.

In the analysis model without the inner diameter recess DI, the axial gap C1 shown in Figure 11 was set to 1.0 mm, the radial length N of the recess D was set to 2.0 mm, and the axial distance Q between the end of the recess D on the outer diameter seal 9 side and the upper spring seat 14 was set to 3.0 mm.

(Analysis results)
An example of the change in flow velocity of water that has entered through the axial gap C1 (see Figures 2, 10 and 11) in the strut bearing device A is shown in the enlarged longitudinal cross-sectional view of a main part in Figure 10 for a case in which an outer diameter side recess DO and an inner diameter side recess DI are present, and in the enlarged longitudinal cross-sectional view of a main part in Figure 11 for a case in which there is only recess D and no inner diameter side recess DI. Also, Figure 12 shows the analysis results of the flow velocity of water that has entered through the "axial gap" in an example analytical model of a strut bearing device that has an "outer diameter side recess DO and inner diameter side recess DI," with the magnitude of the flow velocity being the length of the arrow.

When the flow velocity along the inner surface of the upper case 2 below the outer seal 9 is taken as 1 for an analytical model without an inner recess DI, the flow velocity for an analytical model with an outer recess DO and an inner recess DI is approximately 0.1 to 0.3, demonstrating the significant deceleration effect of the outer recess DO and inner recess DI. This is because, when high-speed water infiltrates through the axial gap C1 of a strut bearing device A that has an outer recess DO and an inner recess DI, the high-speed water first enters the inner recess DI, located radially inward RI of the axial gap C1, and then passes through the outer recess DO before approaching the outer seal 9. Therefore, it is believed that the high-speed water is initially received by the inner recess DI, where it is significantly decelerated, and then further decelerated by the outer recess DO.

[Embodiment 2]
<Strut bearing device>
In the strut bearing device B according to the second embodiment of the present invention, which is shown in the enlarged longitudinal cross-sectional view of a main portion in Figure 13, the same reference numerals as those in Figures 1 to 9 of the first embodiment indicate the same or corresponding parts, portions, locations, etc.

The lower case 3 of the strut bearing 1, which is part of the strut bearing device B, is made of synthetic resin with a built-in core E. The core E is made of steel and is formed by pressing a steel plate, and is quenched and hardened after processing as necessary. The lower case 3 is formed by injection molding with the core E as an insert work.

The lower case 3 has a cylindrical portion 3A and an annular portion 3B that extends radially outward RO from the top of the cylindrical portion 3A. By incorporating a core metal E, the lower case 3 functions as an upper spring seat for the spring support part 13 that supports the upper end of the coil spring 11 (see Figure 1).

<Outer diameter side recess and inner diameter side recess>
The strut bearing device B has an outer diameter recess DO formed in the lower case 3 on the radially inward side RI between the upper case 2 and the lower case 3, and an inner diameter recess DI stepped down from the outer diameter recess DO to the radially inward side RI. The inner diameter recess DI receives muddy water and the like that seeps into the radially inward side RI from the axial gap C2.

The depth H (length in the radial direction R) of the inner diameter recess DI shown in Figure 13 is set to be equal to or greater than the axial clearance C2 (H≧C2), and the position F of the upper end of the inlet of the inner diameter recess DI is set higher than the position G of the upper end of the axial clearance C2. This makes it easier for high-speed water that has entered through the axial clearance C2 to enter the inner diameter recess DI and also makes it easier for the high-speed water to decelerate.

By raising position F of the upper entrance end of the inner diameter recess DI higher than position G, the axial length L becomes larger than the axial clearance C2 (L > C2). Furthermore, based on the analysis results, it is more preferable to set L ≦ 2.0 × C2. Furthermore, based on the analysis results, it is more preferable to set the radial length H of the inner diameter recess DI to H ≧ 2.5 × C2. The inner diameter end of the inner diameter recess DI is positioned radially outward RO from the pitch circle diameter of the rolling elements 6 to suppress deformation of the lower case 3 due to the load received from the rolling elements 6.

<Action and effect>
In the strut bearing device A of Embodiment 1 and the strut bearing device B of Embodiment 2, when high-speed water such as muddy water enters through the axial clearances C1, C2, the high-speed water first enters the inner diameter recess DI, which is located radially inward RI from the axial clearances C1, C2, passes through the outer diameter recess DO, and then approaches the outer diameter seal 9. Therefore, the high-speed water is initially received by the inner diameter recess DI and significantly slowed down, and is further slowed down by the outer diameter recess DO before approaching the outer diameter seal 9, thereby preventing a deterioration in the sealing performance of the outer diameter seal 9.

Furthermore, since it does not have a labyrinth structure and only has an outer diameter recess DO and an inner diameter recess DI, the structure is not complicated and can be simplified, and the drainage of muddy water and other liquids that have entered the interior is not impaired.

The above description of the embodiments is by way of example only and is not intended to be limiting. Various improvements and modifications may be made without departing from the scope of the present invention.

1 Strut bearing 2 Upper case 3 Lower case 3A Cylindrical portion 3B Annular portion 4 Upper raceway 5 Lower raceway 6 Rolling element 7 Cage 8 Inner diameter side seal 9 Outer diameter side seal 10 Strut 11 Coil spring 12 Dust boot 13 Spring support part 14 Upper spring seat 15 Upper insulator 16 Upper mount A, B Strut bearing device C1, C2 Axial clearance D Recess DO Outer diameter side recess DI Inner diameter side recess E Core metal F Position of upper end of entrance of inner diameter side recess G Position of upper end of axial clearance H Depth of inner diameter side recess (radial length)
J Axial direction K Inner protrusion L Axial length of the entrance of the inner diameter side recess M Radial length of the outer diameter side recess N Radial length of the recess O Rotation axis P Axial distance between the outer diameter side seal side end of the outer diameter side recess and the upper spring seat Q Axial distance between the outer diameter side seal side end of the recess and the upper spring seat R Radial direction RI Inner radial direction RO Outer radial direction S Strut type suspension

Claims (3)

A strut bearing device including a strut bearing and an upper spring seat which is a spring support component that supports an upper end of a coil spring,
The strut bearing is
an upper case and a lower case;
an upper raceway ring held by the upper case;
a lower raceway held by the lower case;
a rolling element that rolls between the upper raceway ring and the lower raceway ring;
a seal positioned radially outward of the rolling element;
Equipped with
The upper spring seat contacts the lower case,
an outer diameter side recess formed by the lower case and the upper spring seat, the outer diameter side recess being stepped down radially inward from the outer diameter side recess, the outer diameter side recess being formed by the lower case and the upper spring seat, the inner diameter side recess being stepped down radially inward from the outer diameter side recess,
The inner diameter recess receives muddy water or the like that has infiltrated radially inward from the axial gap.
Strut bearing assembly. The radial length of the inner diameter side recess is equal to or greater than the axial gap,
The position of the upper end of the inlet of the inner diameter side recess is higher than the position of the upper end of the axial gap.
2. The strut bearing assembly of claim 1 . A strut-type suspension for a vehicle, comprising the strut bearing device according to claim 1 or 2 .