JPH0127984Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rack and pinion type steering device, particularly to a rack guide for slidingly supporting a rack bar.

Generally, a rack and pinion type steering device has the structure shown in FIG.

In the figure, 1 is a casing having a hollow part 2 inside, and a pinion 3 at the end of the steering shaft is inserted into the hollow part 2 of the casing 1.
It is rotatably supported by bearings 4 and 5 mounted therein. The casing 1 is integrally formed with a protrusion 7 that extends across the hollow portion 2 in a direction perpendicular to the pinion 3 and has a cylindrical hole 6 on the inner surface. Reference numeral 8 denotes a rack bar having rack teeth 9 that mesh with the pinion 3, and the rack bar 8 is disposed with both ends protruding from the casing 1. Reference numeral 10 denotes a rack guide for slidingly supporting the rack bar 8. The rack guide 10 is disposed within the cylindrical hole 6 of the protrusion 7 of the casing 1 and is biased by a spring 11 that presses the rack bar 8 toward the rack bar 8.

In the rack and pinion type steering device constructed as described above, the rack guide 10 for slidingly supporting the rack bar 8 has conventionally been made of ferrous sintered metal, synthetic resin, or a combination thereof.

In these rack guides, the sliding surface of the rack guide with respect to the rack bar is usually set within an area of a constant band width, as disclosed in U.S. Pat. A design in which a concave curved surface is formed in sliding contact has been widely used.

Although the conventional rack guide made of iron-based sintered metal has sufficient mechanical strength to withstand the impact load from the rack bar, even if the above-mentioned sliding contact mode is adopted, the sliding friction resistance is large, which reduces the efficiency of the steering system. This has caused problems with maneuverability.

On the other hand, a rack guide made of synthetic resin can further reduce the sliding friction resistance by adopting the above-mentioned sliding contact mode. Formed with good dimensional accuracy,
Furthermore, it is difficult to maintain dimensional accuracy after molding, and furthermore, after being assembled into the casing, the rack bar undergoes thermal expansion and contraction under the influence of the temperature rise of the steering device, resulting in thermal deformation and creep. There are problems such as making it difficult to support the smooth sliding.

Furthermore, a synthetic resin is used on the sliding surface side of the rack bar, and the synthetic resin is combined with a guide base made of sintered metal or synthetic resin with reinforcing filler.The Rack Guide exhibits the properties of the synthetic resin (self-lubricating property). Although the sliding friction resistance is reduced, there is a problem in that the synthetic resin forming the sliding surface undergoes plastic flow in response to the impact load from the rack bar, which prevents smooth sliding of the rack bar.

In view of the above-mentioned problems, the inventor of the present application previously proposed in Utility Application No. 58-200303 (Utility Model Application No. 105568-1988; hereinafter referred to as "prior art") that the guide base was made of a sintered metal material or a reinforcing filler. It is formed of synthetic resin, and the sliding surface side of the base is made of a multilayer material, that is, a thin steel plate, a porous sintered metal layer integrally formed on the thin steel plate, and a porous sintered metal layer impregnated with the sintered metal layer. We have proposed a rack guide in which a sliding piece formed of a multilayer material, a part of which is formed of a synthetic resin layer formed as a thin layer on the sintered metal layer, is fitted and held.

This prior art is illustrated in the drawings as shown in FIGS. 2 to 5.

Figure 2 is a partially cutaway plan view of the rack guide, Figure 3 is a sectional view taken along line A-A in Figure 2, and Figure 4 is Figure 2B.
-B sectional view and FIG. 5 are plan views showing a sliding piece material taken from a multilayer material.

The rack guide 10 consists of a base body 12 made of a sintered metal material or a synthetic resin containing a reinforcing filler, and a sliding piece 13 made of a multilayer material that is fitted and held on the base body 12.

The base body 12 has a cylindrical outer peripheral surface 14, a concave curved seat 15 at one end, a hollow cylindrical section 16 at the other end, and a hollow cylindrical section at the bottom of the concave curved seat 15. A circular hole 17 communicating with 16 is provided.

Band-shaped protrusions 18, 18 of uniform height are formed along the curved surface at the peripheral edge of the concave curved seat 15, and surround the concave groove 15.

The sliding piece 13 made of a multilayer material has inner and outer circumferential surfaces 19 and 20 formed with the synthetic resin layer inside, and a protrusion 21 integrally formed on the outer circumferential surface 20.
have. At least the inner circumferential surface 19 of the sliding piece 13 is in sliding contact with the outer circumferential arcuate surface of the rack bar 8 from 30 degrees from the axis of the rack guide 10.
In other words, a position displaced upward and laterally from the center of curvature O of the outer circumferential arcuate surface of the rack bar 8 so as to be set within the width between 4 o'clock and 5 o'clock and 7 o'clock and 8 o'clock on the clock. with centers O ₁ and O ₂ ,
The rack bar 8 is formed into a concave curved surface with radii of curvature R ₁ and R ₂ larger than the radius of curvature R of the outer circumferential arcuate surface.

The sliding piece 13 is fitted and held in the concave curved seat 15 by press-fitting the protrusion 21 into the circular hole 17 of the concave curved seat 15 and causing the inner peripheral surface 19 to protrude from the band-shaped protrusions 18, 18. Ru.

In the rack guide 10 having such a structure, the synthetic resin layer forming the sliding surface is extremely thin;
Since the synthetic resin layer is supported by a porous sintered metal layer and a thin steel plate, its pressure resistance is increased and it can sufficiently withstand the impact load from the rack bar 8. 13 is the outer peripheral surface 2
Since the protrusion 21 integrally formed on the base body 12 is press-fitted into the circular hole 17 formed in the concave curved seat 15 of the base body 12, movement (displacement) of the sliding piece 13 on the base body 12 is restricted. , there will be no drawbacks such as changes in the sliding position due to the movement of the sliding piece 13;
Although success was achieved in terms of performance, problems were raised particularly in terms of manufacturing, especially when forming the sliding piece 13.

In the above-mentioned prior art, the sliding piece 13 is formed by bending a sliding piece material 13' that is punched out from a plate-shaped multilayer material into a shape that matches the shape of the concave curved seat 15 of the base body 12. It is formed by

That is, as shown in FIG. 2, the concave curved seat 15 of the base body 12 has a substantially circular planar shape with a chord part at a symmetrical position, and as shown in FIG. 3, its A-A cross-sectional shape is a semicircle. It exhibits a slightly smaller circular arc, and as shown in FIG. 4, its BB cross-sectional shape is approximately trapezoidal.

Therefore, in order to form the sliding piece 13 that matches the shape of the concave curved seat 15, first, as shown in FIG. 5, a circular arc portion 22,
22, straight portions 23, 23, 23, 23 extending in tangential directions intersecting each other from both circular arc portions 22, 22 at symmetrical positions sandwiching the circular arc portions 22, 22, and straight portions parallel to each other at both ends. A sliding piece material 13' having 24, 24 is taken out by punching, and the material 13' is formed with inner and outer peripheral surfaces 19, 20 by bending with the synthetic resin layer inside.

In this method, the sliding piece material 13' is made from a multilayer material.
There is a manufacturing problem in that there is a large material loss when the material is extracted by punching, and the yield is poor.

In addition, in terms of performance, the inner peripheral surface 19 of the sliding piece 13
When the above-mentioned rack bar 8 is brought into sliding contact within a region of a constant band width, the inner circumferential surface of the sliding piece 1
It was found that the area above the sliding contact area of the rack bar 9 was not involved in sliding contact with the rack bar 8 at all.

The present invention utilizes the combination of the base and the sliding piece made of multi-layered material, which has been successful in terms of performance, as is, and based on the above knowledge, it increases the sliding area with the rack bar as much as possible compared to the prior art. The technical object is to obtain a rack guide which solves the above-mentioned problems in manufacturing the sliding piece by suppressing the decrease in allowable load capacity as much as possible without reducing the load capacity.

In order to achieve the above-mentioned technical problem, the technical means of the present invention, that is, the configuration is as follows.

A rack pinion consisting of a pinion rotatably supported by a casing, a rack bar having rack teeth that mesh with the pinion, a rack guide located within the casing that slides and supports the rack bar, and a spring that presses the rack guide toward the rack bar. In the type steering device, the rack guide includes a base made of metal or synthetic resin with reinforcing filler, a thin steel plate fitted and held on the base, and a porous sintered metal layer integrally formed on the thin steel plate. and a sliding piece made of a multilayer material impregnated with the sintered metal layer and a part of which is formed of a synthetic resin layer formed as a thin layer on the sintered metal layer. The base body has a cylindrical outer peripheral surface, a concave curved seat at one end, and a hollow cylindrical portion at the other end. The concave curved seat of the base body has a planar shape that is approximately circular with a chord part at a symmetrical position, and a cross-sectional shape along the curved surface that is slightly smaller than a semicircle, and is perpendicular to the curved surface and has a central cross section that includes the axis. The projected shape of the concave curved seat is approximately trapezoidal, and the concave curved seat has a concave groove formed along the curved surface with a width larger than the length of the string part, and a circle communicating with the hollow cylindrical part at the bottom of the concave groove. Holes must be formed. The sliding piece is made of the multilayer material and has a rectangular shape and has a width matching the width of the groove and a length corresponding to an arc length extending over the length of the vertical wall of the groove. It has an inner and outer circumferential surface formed by bending a piece of material with its synthetic resin layer facing inside, and is provided with a protrusion integrally formed on the outer circumferential surface. At least the inner circumferential surface of the sliding piece is arranged so that the sliding contact position of the outer circumferential arcuate surface of the rack bar is set within a width of 30 degrees to 60 degrees from the axis of the rack guide. It is formed into a curved surface whose center is located above and laterally displaced from the center of curvature, and whose radius of curvature is larger than the radius of curvature of the outer circumferential arc-shaped surface of the rack bar. The sliding piece has a protrusion on its outer circumferential surface that is press-fitted into a circular hole formed in the bottom of the groove of the base body, and its inner circumferential surface projects from the vertical wall of the groove so that it is fitted and held in the groove. To be there. that's all~
This is a rack and pinion type steering device characterized by the following configuration.

In the easy guide with the above-mentioned configuration,
The base body is made of a sintered metal material or a synthetic resin containing a reinforcing filler such as glass fiber or carbon fiber. Examples of synthetic resins impregnated into the porous sintered metal layer of the multilayer material and partially formed as a thin layer on the sintered metal layer include polytetrafluoroethylene resin, polyacetal resin, or lubricated resin. A synthetic resin having self-lubricating properties and wear resistance, such as an oil-impregnated polyacetal resin containing an oil agent, is used.

The sliding piece to be fitted and held on the base is cut from a plate-shaped multilayer material into a rectangular shape with a width that matches the width of the groove formed in the concave curved seat of the base, and this is used as the sliding piece material. By bending the material with the synthetic resin layer on the inside, at least the inner peripheral surface has a sliding contact position with the outer circumferential arcuate surface of the rack bar from 30 degrees to 60 degrees, preferably from 30 degrees to 45 degrees from the axis of the rack bar. In other words, from 4 o'clock to 5 o'clock and from 7 o'clock to 8 o'clock
above and laterally above the center of curvature of the outer circumferential arcuate surface of the rack bar so that The rack bar has a curved surface whose center is at a position displaced from the center and has a radius of curvature larger than the radius of curvature of the outer circumferential arc-shaped surface of the rack bar. It has manufacturing advantages in that there is no oxidation and the yield is significantly improved compared to the prior art.

In terms of performance, it has the following effects.

When the rack guide configured as described above is incorporated into the rack and pinion type steering device,
The rack bar is slidably supported on the inner peripheral surface of the sliding piece constituting the rack guide.

The inner circumferential surface of this sliding piece is formed of a synthetic resin layer, and the contact with the rack bar is a line or minute band-like contact within a sliding contact area of a certain width.
Therefore, the sliding friction resistance in this sliding portion is significantly reduced.

By forming the sliding piece from a rectangular sliding piece material, the sliding area between the inner circumferential surface of the sliding piece and the outer circumferential arcuate surface of the rack bar is not significantly reduced compared to the prior art. It is possible to suppress the decrease in allowable load capacity due to the decrease as much as possible.

Even if the synthetic resin layer on the inner peripheral surface of the sliding piece wears out, the synthetic resin impregnated in the porous sintered metal layer will be exposed on the sliding surface, so the reduction in sliding friction resistance will continue for a long time. maintained across the board.

The synthetic resin layer is extremely thin and is supported by a porous sintered metal layer and a thin steel plate, so it has high pressure resistance against the impact load from the rack bar. Therefore, the plastic flow of the synthetic resin in the prior art does not occur at all and does not interfere with the smooth sliding of the rack bar.

The sliding piece has a projection integrally formed on the outer circumferential surface that is press-fitted into a circular hole provided in a groove in the concave curved seat of the base, so there is no movement (shift) of the sliding piece on the base. Therefore, problems such as changes in the sliding contact position due to the movement of the sliding piece do not occur.

Hereinafter, the present invention will be explained with reference to FIGS. 6 to 10 of the accompanying drawings showing embodiments thereof.

FIG. 6 is a partially cutaway plan view of the rack guide, FIG. 7 is a sectional view taken along the line - - in FIG. 6, FIG. 8 is a sectional view taken along the line - - in FIG. An enlarged cross-sectional view of the layer material, Figure 10 shows a multi-layer material (hoop material) formed into a strip shape to obtain the sliding piece material.
FIG.

The rack guide 100 includes a base body 101 and the base body 10.
1 and a sliding piece 102 that is fitted and held in the sliding piece 102.

The base body 101 is made of a sintered metal material or a synthetic resin containing a reinforcing filler, and has a cylindrical surface 10 on its outer peripheral surface.
3, and has a concave curved seat 104 at one end and a hollow cylindrical portion 105 at the other end.

As shown in FIG. 6, the concave curved seat 104 has a substantially circular planar shape with chord parts 106, 106 at symmetrical positions, and as shown in FIG. 7, its cross-sectional shape is slightly more than a semicircle. It exhibits a small circular arc, and as shown in FIG. 8, its elevational shape when viewed from a cross section is approximately trapezoidal.

107 is a concave groove along the curved surface formed in the concave curved seat 104;
It has a width larger than the length of the string section 106 of the 04.

108, 108 are vertical walls of the groove 107.

109 is a circular hole provided at the bottom of the groove 107, and the circular hole 109 communicates with the hollow cylindrical portion 105.

As shown in FIG. 9, the sliding piece 102 fitted and held on the base body 101 is made of a multilayer material 110, that is, a thin steel plate 111 and a porous sintered metal layer integrally formed on the thin steel plate 111. 112 and the sintered metal layer 1
12 and a portion thereof is impregnated with the sintered metal layer 11
2 and a synthetic resin layer 113 formed as a thin layer on top of the multilayer material 110 of equal thickness.

The sliding piece 102 is made of a plate-shaped multilayer material 111.
As shown in FIG.
07 is cut into a rectangular shape with a length corresponding to the arc length extending over the length of the vertical wall 108, and this is used as the sliding piece material 102' and bent with the synthetic resin layer inside to form the inner and outer circumferential surfaces 114. , 115.

At this time, at least the inner peripheral surface 1 of the sliding piece 102
14, the position of sliding contact with the outer circumferential arcuate surface of the rack bar 8 is from 30 degrees to 60 degrees from the axis of the rack guide, respectively.
degrees, preferably between 30 degrees and 45 degrees, in other words from 4 o'clock to 5 o'clock and from 7 o'clock to 8 o'clock, preferably 4 o'clock
The center is located above and laterally displaced from the center of curvature O of the outer circumferential arcuate surface of the rack bar 8 so as to be set within an area of a certain width between half past five o'clock and seven thirty and seven o'clock. O ₁ , O ₂ and formed into a curved surface drawn with radii of curvature R ₁ , R ₂ larger than the radius of curvature R of the outer circumferential arc-shaped surface of the rack bar 8,
The outer circumferential surface 115 is formed into an arcuate surface in accordance with the inner circumferential surface 114.

In this embodiment, the sliding contact positions of the inner peripheral surface 114 of the sliding piece 102 and the outer peripheral arcuate surface of the rack bar 8 are set at 45 degrees from the axis of the rack guide, in other words, at 4:30 and 7:30 on the clock. An example is shown in which the position is set (Fig. 7).

116 is a projection integrally formed on the outer peripheral surface 115 of the sliding piece 102 with a through hole 117.

This protrusion 116 is formed by, for example, burring.

The sliding piece 102 formed in this way has the outer peripheral surface 1
The protrusion 116 formed on the base concave curved seat 10
It is press-fitted into the circular hole 109 provided in the groove 107 of No. 4, and the inner peripheral surface 114 is inserted into the groove 10.
The rack guide 100 is configured by projecting from the vertical wall 108 of No. 7 and being fitted and held in the groove 107.

When this rack guide 100 is incorporated into a rack and pinion type steering device, the rack guide 1
The rack bar 8 is slidably supported on the inner peripheral surface 114 of the sliding piece 102 of 00, and the rack bar 8 makes linear or minute sliding contact at a position of 45 degrees from the rack guide axis of the sliding piece inner peripheral surface 114. It is slidably supported by.

FIG. 11 shows another embodiment of the rack guide, in particular one in which the sliding piece 102 is fitted and held onto the base body 101 more reliably.

In the embodiment described above, the sliding piece 102 has a protrusion 116 integrally formed on the outer circumferential surface 115 and a circular hole 1 provided in the concave groove 107 of the concave curved seat 104 of the base body.
09 and is fit and held in the base body 101.

However, in the unlikely event that the press-fitting between the protrusion 116 and the circular hole 109 is incomplete, the sliding piece 102 will rotate around the axis of the protrusion 116 on the base body 101 and rotate in the direction along the curved surface. Rotation and linear movement in the axial direction perpendicular to the curved surface will occur.

Rotation around the axis of the protrusion 116 and linear movement in the axial direction perpendicular to the curved surface are restricted by the vertical walls 108, 108 of the groove 107, but rotation in the direction along the curved surface is restricted. No measures have been taken to regulate this.

In this embodiment, rotation of the sliding piece 102 in the direction along the curved surface of the base body 101 is restricted.

That is, in the groove 107 along the curved surface formed in the concave curved seat 104 of the base body 101, the vertical wall 1 of the groove is formed.
08, 108 are formed with plane parts 118, 118 facing each other, and the plane parts 118,
Arc parts 119, 119 having the same center of curvature as the groove 107 are formed from the groove 118 to the end.

Since the flat portions 118, 118 form discontinuous surfaces in the groove 107, rotation of the sliding piece 102 fitted and held in the groove 107 in the direction along the curved surface is restricted.

Other functions and effects are exactly the same as those of the embodiment described above.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a rack and pinion type steering device, Fig. 2 is a partially cutaway plan view showing a rack guide in the prior art, Fig. 3 is a sectional view taken along line AA in Fig. 2, and Fig. 4 is a sectional view showing a rack guide in the prior art. BB sectional view in Figure 2,
Fig. 5 is a plan view showing a sliding piece material obtained from the multi-layer material of the prior art, Fig. 6 and the following are drawings showing embodiments of the present invention, and Fig. 6 is a partially cutaway plane of the rack guide. 7 is a sectional view of FIG. 6, FIG. 8 is a sectional view of FIG. Plan view showing the sliding piece material, No. 11
The figure is a longitudinal sectional view showing another embodiment. 8...Rack bar, 100...Rack guide,
101...base body, 102...sliding piece, 104...
Concave curved seat, 105... Hollow cylinder part, 106... String part, 107... Concave groove, 108... Vertical wall, 110...
...Multilayer material, 114...Inner peripheral surface, 115...Outer peripheral surface, 116...Protrusion.

Claims (1)

[Claims for Utility Model Registration] A pinion 3 rotatably supported by a casing 1, a rack bar 8 having rack teeth 9 that mesh with the pinion, and a rack guide 100 that is inside the casing 1 and slidably supports the rack bar 8. and a spring 11 that presses the rack guide 100 toward the rack bar 8. The rack guide 100 includes a base body 101 made of metal or synthetic resin containing a reinforcing filler, and a thin base body 101 that is fitted and held by the base body 101. A steel plate 111, a porous sintered metal layer 112 integrally formed on the thin steel plate 111, and a porous sintered metal layer 112 impregnated with the sintered metal layer 112 and a part of which is formed as a thin layer on the sintered metal layer. and a sliding piece 102 made of a multilayer material 110 made of a synthetic resin layer 113. The base body 101 has a cylindrical outer surface 103, a concave curved seat 104 at one end, and a hollow cylindrical portion 105 at the other end. The concave curved seat 104 of the base body 101 has a substantially circular planar shape with chord parts 106, 106 at symmetrical positions, and a cross-sectional shape along the curved surface is an arc slightly smaller than a semicircle, and the axis is perpendicular to the curved surface. The projected shape from the central cross section including the curved surface is approximately trapezoidal, and the concave curved seat 104 has a concave groove 107 formed along the curved surface and having a width larger than the length of the string section 106. A circular hole 109 communicating with the hollow cylindrical portion 105 is formed at the bottom. The sliding piece 102 has a width that matches the width of the groove 107, and the vertical wall 108 of the groove 107.
The inner and outer circumferential surfaces are formed by bending a rectangular sliding piece material 102' made of the multilayer material 110 with a length corresponding to the arc length extending over the length of the sliding piece material 102' with the synthetic resin layer 113 inside. 11
4, 115 and a protrusion 116 integrally formed on the outer peripheral surface 115. At least the inner peripheral surface 114 of the sliding piece 102 is arranged so that the sliding contact position with the outer circumferential arcuate surface of the rack bar 8 is set within a width of 30 degrees to 60 degrees from the axis of the rack guide 100. Centers O ₁ and O ₂ are located above and laterally displaced from the center of curvature O of the outer circumferential arcuate surface of No. 8.
, and is formed into a curved surface drawn with radii of curvature R ₁ and R ₂ larger than the radius of curvature R of the outer circumferential arc-shaped surface of the rack bar 8. The sliding piece 102 has a protrusion 116 on the outer peripheral surface 115.
is press-fitted into the circular hole 109 formed on the bottom surface of the concave groove 107 of the base body 101, and the inner peripheral surface 114 is press-fitted.
protrudes from the vertical wall 108 of the groove 107 and is fitted and held in the groove 107. A rack and pinion steering device characterized by the above configuration.