JPS637703Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a bearing that supports a shaft that rotates or slides back and forth in the axial direction, such as a steering column of an automobile or a rack bar of a rack and pinion type steering device.

Such bearings play the role of smoothly slidingly supporting a shaft that rotates or slides back and forth in the axial direction due to steering operation, but since there is usually a small gap between the shaft and the shaft, When a shock or local force is applied, vibration or abnormal noise is generated.
The problem is that vibrations or abnormal noises are transmitted to the interior of the vehicle through various mounting plates, etc., and there are manufacturing oversights in the components of the bearing, such as the inner and outer diameters of the bearing, the inner diameter of the housing, and the shaft diameter. In addition, in the case of synthetic resin bearings in particular, thermal history due to repeated temperature changes causes shrinkage, which reduces the inner diameter of the bearing. The problem is that the shaft is strongly pressed against the shaft, increasing the operating torque.

Therefore, such a bearing is required to have a configuration that eliminates the above-mentioned problems.

Therefore, as shown in Japanese Utility Model Publication No. 46-23135 or Japanese Patent Publication No. 50-12174, bearings that slidingly support steering columns or rack bars of automobiles have been used to reduce vibrations generated in the shaft. In the latter case, the rubber elastic body vulcanized and bonded integrally with the bearing absorbs and relaxes the bearing.

These are shown in the drawings as follows.

1 and 2 are cross-sectional views of such a bearing.

In FIG. 1, reference numeral 1 denotes a bearing that integrally has a substantially cylindrical base portion 2 made of synthetic resin and a substantially frustoconical surface portion 3 having a narrowed inner diameter at one axial end of the base portion 2. Reference numeral 4 denotes a plurality of grooves extending along the axial direction over substantially the entire length of the frusto-conical surface portion 3. Reference numeral 5 denotes an elastic tongue portion formed by the cut groove 4. 6 is a housing that fixes the bearing 1, and 7 is a shaft that is slidably supported by the bearing 1.

Further, in FIG. 2, reference numeral 1' denotes a bearing composed of a synthetic resin bearing bush 2' and a rubber elastic cylindrical body 3' which is vulcanized and integrated with the outer peripheral surface of the bearing bush 2'. 4' is a housing, in which the bearing 1' is press-fitted with its rubber elastic cylindrical body 3' into the inner surface of the housing, and is fixed by applying a preload force to the bearing bush 2'. . 5' is a rack bar slidably supported by the bearing 1'.

In the above conventional technology, in the former case, the shaft 7 is elastically supported by the elastic tongue portion 5 of the bearing 1;
Even if the tongue part 5 receives vibration, the vibration is absorbed by the elastic action of the tongue part 5.

However, during use, the elastic tongue portion 5 plastically deforms, increasing the clearance with the shaft 7, making it impossible to elastically support the shaft 7, and at the same time often generating abnormal noise, which poses problems for long-term use. There is.

In the latter case, vibrations applied to the rack bar 5' are absorbed by the rubber elastic cylindrical body 3';
Each component of the bearing part, especially the bearing bush 2'
There is a problem of variations in operating torque due to variations in dimensional tolerances that are inevitable during manufacturing, such as the inner diameter of the housing, the inner diameter of the rubber shaft, and the shaft diameter of the rubber shaft.Furthermore, the repeated temperature changes that are inevitable for this type of bearing cause heat loss. The problem of shrinkage of the synthetic resin bearing bushing 2' when subjected to hysteresis, which reduces the inner diameter of the bushing and strongly presses the rack bar 5' and increases the operating torque, remains unsolved.

This variation in the operating torque and the increase in the operating torque cause the steering operation to become heavier and difficult to perform smoothly.

The present invention relates to the improvement of the latter type of bearing mentioned above, and is particularly concerned with absorbing variations in dimensional tolerances that cannot be avoided during manufacturing of each component of the bearing part, and furthermore, in cases where the bearing is subject to thermal history due to repeated temperature changes. However, the technical problem is to obtain a bearing with a desired operating torque by adopting a configuration that relieves the influence of shrinkage that occurs in the bearing.

In order to solve the above-mentioned technical problem, the present invention forms a cylindrical jacket made of a rubber elastic body or a synthetic resin having elasticity and a synthetic resin cylindrical bushing fitted into the cylindrical jacket separately, and the cylindrical bushing is The technical means is to provide a degree of freedom of deformation in the radial direction within the cylindrical jacket.

More specifically, a cylindrical mantle made of a rubber elastic body or a synthetic resin with elasticity is formed with a narrowed part facing inward in the radial direction at one end thereof, and a constricted part is formed on the inner circumferential surface of the cylindrical mantle and is connected to the narrowed part. A synthetic resin cylindrical bushing is formed with a protrusion that extends in the axial direction to the end opposite to the narrowed part, and has a slotted groove that penetrates in the axial direction within the cylindrical jacket. By fitting the cylindrical bush with a gap between the circumferential end face of the bush and the protrusion side of the inner peripheral surface of the cylindrical mantle, the cylindrical bush has a degree of freedom in deformation in the radial direction within the cylindrical mantle. It is to give.

Here, synthetic resin with elasticity is flexible and strong, and has approximately Shore hardness (D type).
40 to 60, and a rebound resilience value (JIS K6301) of 50 to 80, and still has rubber-like elastic behavior, such as polyester/ether copolymer or polyurethane.

The synthetic resin forming the cylindrical bushing has excellent self-lubricating properties and wear resistance, such as polyacetal resin or oil-impregnated polyacetal resin containing a lubricant.

By taking such technical measures, the cylindrical bushing has a side surface of a protrusion formed on the inner circumferential surface of the cylindrical bushing, and a circumferential end face of the bushing formed by the cut groove. are fitted with gaps between each other, giving the cylindrical bushing a degree of freedom in deformation in the radial direction. Even if there are unavoidable dimensional tolerance variations in the inner diameter and shaft diameter of the cylinder, and these influence each other, the elastic deformation of the cylindrical jacket and the degree of freedom of deformation in the radial direction of the cylindrical bushing will prevent these variations. Variations are absorbed and the shaft can be slidably supported with the desired operating torque.

In addition, even if the bearing is subjected to thermal history due to repeated temperature changes, the cylindrical bushing that slides and supports the shaft has a cut groove, so the inner diameter of the cylindrical bushing will not be reduced. Since this occurs along the circumferential direction of the cylindrical bushing, there is no problem of strongly pressing the shaft and increasing the operating torque.

Since vibrations applied to the shaft are absorbed and alleviated by the cylindrical jacket, they are not transmitted to the interior of the vehicle through various mounting plates and the like.

Further, since the engagement between the cut groove of the cylindrical bushing and the protrusion on the inner circumferential surface of the cylindrical bushing acts as a means for preventing rotation of the cylindrical bushing within the cylindrical mantle, there is no need to provide a separate anti-rotation means.

In the present invention, forming a plurality of concavo-convex portions (serrations) in the axial direction on the outer peripheral surface of the cylindrical mantle made of a rubber elastic body or an elastic synthetic resin further increases the elastic effect of the cylindrical mantle. This allows for smooth insertion into the housing.

Furthermore, it is effective from the viewpoint of friction and wear to form a plurality of annular recesses on the inner circumferential surface of the synthetic resin cylindrical bushing having slotted grooves, and to use the annular recesses as reservoirs for lubricant such as grease.

Further, by integrally forming a flange on one end of the cylindrical bushing and locking the end face of the flange within the housing with, for example, a retaining ring, the other end of the cylindrical bushing can fit into the narrowed part of the cylindrical jacket. Since the cylindrical bushing is abutted against and locked, the cylindrical bushing is prevented from coming off from the cylindrical jacket in the axial direction.

Next, an embodiment of the technical means of the present invention will be described with reference to FIGS. 3 and 4.

In the figure, reference numeral 10 denotes a cylindrical jacket 20 made of a rubber elastic body or an elastic synthetic resin, and a synthetic resin cylindrical bush 30 fitted into the cylindrical jacket 20.
It is a bearing consisting of.

Reference numeral 21 denotes a narrowed portion formed at one end of the cylindrical mantle 20 radially inward.

22 is the narrowed portion 21 on the inner peripheral surface of the cylindrical mantle 20;
It is a single protrusion formed to extend in the axial direction to the end opposite to the narrowed part 21.

Reference numeral 31 denotes a slit groove formed in the cylindrical bushing 30 in the axial direction thereof.

The cylindrical bush 30 has a gap S between the circumferential end surface formed by the cut groove 31 and the side surface of the protrusion 22 formed on the inner peripheral surface of the cylindrical bush 20. It is inserted into 20,
The cylindrical bush 30 is given a degree of freedom of deformation within the cylindrical jacket 20 in its radial direction.

40 is a housing, and 50 is a shaft.

5 and 6 show other embodiments of the technical means of the present invention.

In this embodiment, a plurality of concavo-convex portions (serrations) 23 are formed on the outer circumferential surface of the cylindrical mantle 20 made of a rubber elastic body or a synthetic resin having elasticity, and a cut groove 31
A plurality of annular recesses 32 are formed on the inner circumferential surface of the synthetic resin cylindrical bushing 30, and the annular recesses 32 serve as reservoirs for lubricant such as grease. This embodiment is the same as the embodiment shown in FIGS. 3 and 4, except that the flange portion 33 having a cut groove continuous with the formed cut groove 31 is integrally formed.

[Brief explanation of the drawing]

Figure 1 is a partial vertical sectional view showing a conventional bearing, Figure 2
The figure is a longitudinal sectional view showing a conventional bearing, Fig. 3 is a longitudinal sectional view showing a bearing of the present invention, Fig. 4 is a sectional view taken along the line X-X in Fig. 3, and Fig. 5 is a longitudinal sectional view of another bearing of the present invention. FIG. 6 is a longitudinal cross-sectional view showing the embodiment, and FIG. 6 is a cross-sectional view taken along line Y--Y in FIG. DESCRIPTION OF SYMBOLS 10... Bearing, 20... Cylindrical mantle, 21... Constriction part, 22... Projection part, 30... Cylindrical bushing,
31... Cut groove.

Claims (1)

[Scope of utility model registration request] A cylindrical mantle made of a rubber elastic body or an elastic synthetic resin has a constricted part formed radially inward at one end thereof, and a constricted part is formed on the inner circumferential surface of the cylindrical mantle in a continuous manner with the constricted part. A single protrusion is formed that extends in the axial direction to the end opposite to the narrowed part, and a synthetic resin cylindrical bushing having a slotted groove passing through the cylindrical jacket in the axial direction is formed in the slotted groove. A bearing characterized in that the bearing is fitted with a gap between the circumferential end surface of the cylindrical bushing and the side surface of the protrusion on the inner circumferential surface of the cylindrical jacket.