JP2006116994A - Rack guide, and rack and pinion type steering device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack guide capable of preventing an abrupt increase in the sliding friction resistance and preventing degradation of the steering feeling attributable to the increased sliding friction resistance even when the lubricant applied during the assembly flows out or runs short, and provide a rack and pinion type steering device having the rack guide. <P>SOLUTION: In the rack guide 20, a double-layered sliding piece 40 comprising a back metal 41, a porous metal sintered layer 42 integrated with the surface of the back metal 41, and a synthetic resin layer 43 filled and coated in a hole gap and the surface of the porous metal sintered layer 42 is seated on a recessed surface 35 of a rack guide base body 30 having a pair of flat surfaces 32, a pair of inclined surfaces 33 and a bottom flat surface 34. A recess 47 is formed in an inclined surface part 43a of the double-layered sliding piece 40. The recess 47 in the inclined surface part 43a has the depth with which a top surface 43b of the synthetic resin layer 43 is aligned with a surface 42a of the porous metal sintered layer 42, and lubricant is filled in the recess 47 in the inclined surface part 43a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rack guide used in a rack and pinion type steering device for an automobile and a rack and pinion type steering device including the same.

Japanese Patent Laid-Open No. 50-102027 Japanese Utility Model Publication No. 1-24955 Japanese Utility Model Publication No. 2-96268 JP 2002-370654 A

  The rack and pinion type steering device generally has a configuration as shown in FIG. 9, and the rack and pinion type steering device 1 shown in FIG. 9 has bearings 4 and 5 in the casing 3 so as to be rotated by a steering operation. A pinion 6 rotatably arranged via the pinion, and a rack bar 8 having a rack tooth 7 meshed with the pinion 6 so as to be moved in a direction perpendicular to the paper surface by the rotation of the pinion 6, In order to guide the movement of the rack bar 8, the rack bar 8 is slidably arranged in the hole 9 extending in the lateral direction in the casing 3 (a direction orthogonal to the movement direction of the rack bar 8). A rack guide 10 to be supported, and a coil spring 11 that is arranged between the casing 3 and the rack guide 10 and elastically presses the rack teeth 7 of the rack bar 8 against the pinion 6 via the rack guide 10. Bei was composed.

  By the way, in the rack and pinion type steering device 1 described above, iron-based sintered metal or synthetic resin is used as the rack guide 10 that slidably supports the rack bar 8. However, the rack guide made of iron-based sintered metal has sufficient mechanical strength against the impact load from the rack bar 8, but has a large sliding friction resistance, which reduces the efficiency of the steering system and causes a problem in maneuverability. Is leaving. On the other hand, the rack guide made of synthetic resin can reduce sliding frictional resistance, but it is inferior in mechanical strength against impact load, and causes dimensional variations due to molding shrinkage, etc. It is difficult to maintain the dimensional accuracy later, and after being assembled in the housing, the rack and pinion type steering device 1 is affected by the temperature rise, causing thermal expansion and contraction, resulting in thermal deformation and creep. There are problems such as difficulty in supporting the bar 8 smoothly and slidably.

  In order to solve these problems, a sliding piece made of a synthetic resin having self-lubricating and wear resistance on the sliding surface side that slidably supports the rack bar, or a back plate made of a steel plate and the surface of the back plate A sliding piece made of a multilayered material having a three-layer structure of an integrally formed porous metal sintered layer and pores of this porous metal sintered layer and a synthetic resin layer filled and coated on the surface is formed into a sintered metal. There has been proposed a rack guide combined with a rack guide base made of (see Patent Document 1 and Patent Document 2).

  The rack guide composed of the combination of the sliding piece and the rack guide base described above has the advantage that the mechanical strength is increased and the sliding frictional resistance is reduced as compared with the rack guide described above. .

  However, even in a rack guide composed of a combination of the above sliding piece and the rack guide base, in many cases, lubricating oil such as grease is supplied to the sliding surface between the sliding piece and the rack bar as much as possible. The sliding frictional resistance is reduced, and smooth sliding guidance is performed. However, the supply of the lubricant to the sliding surface is usually performed by applying the lubricant to the sliding surface at the time of assembly, and the assembly is performed by repeatedly performing the sliding guide operation between the sliding piece and the rack bar. Occasionally, problems such as the outflow and depletion of the applied lubricant occur, and there is a problem that the effect of reducing sliding frictional resistance at the initial stage of assembly is gradually lost.

  As a means for solving such a problem, there has also been proposed a rack guide in which a plurality of recesses as a retaining portion for a lubricant such as grease are formed on a sliding surface of the rack guide with a rack bar (Patent Documents 3 and 3). (See Patent Document 4).

  However, even in the above method, in the rack guide composed of the combination of the sliding piece and the rack guide base, the sliding piece itself is thin, so that the recess formed in the sliding piece is shallow. There is no choice but to reduce the amount of lubricating oil that accumulates in the recess itself, and as a result, there is a problem in that it is difficult to perform smooth sliding guidance over a long period of time by reducing sliding frictional resistance.

  The present invention has been made in view of the above-mentioned points, and an object of the present invention is a rack guide composed of a combination of a sliding piece and a rack guide base, and the outflow and depletion of the lubricant applied during assembly. The rack guide that can prevent an abrupt increase in sliding frictional resistance even in the case of occurrence of the like, and can prevent deterioration of the steering feeling caused by the increase in sliding frictional resistance, and a rack and pinion type steering equipped with the rack guide To provide an apparatus.

  The rack guide of the present invention includes a pair of flat surfaces opposed to each other, a pair of inclined surfaces extending integrally from each other of the pair of flat surfaces, and a bottom flat surface integrally extending from the pair of flat surfaces. The concave surface of the rack guide base body having a concave surface with a concave portion at the center of the flat bottom surface of the concave surface and having a cylindrical outer peripheral surface is provided with a back plate made of a steel plate and a porous integrally formed on the surface of the back plate. A porous resin sintered layer and a synthetic resin layer filled and coated on the surface of the porous metal sintered layer, and a pair of opposed inclined surface portions and a pair of flat surface portions continuous to the inclined surface portions, A multi-layer sliding piece having a bottom surface continuous to each of the flat surface portions and a hollow protrusion extending to the back metal at the center of the bottom surface portion is connected to the bottom of the rack guide base. It is seated by fitting it into the recess in the center of the flat surface. The inclined surface portion of the multilayer sliding piece has at least one recess having a step in each of the back metal, the porous metal sintered layer, and the synthetic resin layer in the thickness direction of the multilayer sliding piece. The recessed portion of the inclined surface portion has a depth at which the bottom surface of the step of the synthetic resin layer coincides with at least the surface of the porous metal sintered layer, and the recessed portion of the inclined surface portion is lubricated. It is filled with an oil agent.

  According to the rack guide of the present invention, at least one recess is formed in the sliding surface (inclined surface portion) of the multilayer sliding piece that slidably supports the rack bar. Since a lubricant such as grease filled and applied at the time of assembly is interposed, the rack bar is smoothly guided by the handle operation. In addition, since the recess of the inclined surface portion is formed with a step in each of the backing metal, the porous metal sintered layer, and the synthetic resin layer in the thickness direction of the multilayer sliding piece, the multilayer sliding piece and the rack During sliding with the bar, wear of the synthetic resin layer on the sliding surface of the multilayer sliding piece proceeds, and sliding between the synthetic resin layer of the multilayer sliding piece and the rack bar is a porous metal sintered layer. Even when the synthetic resin filled in the pores of the porous metal sintered layer and the rack bar are slid, the bottom surface of the step of the synthetic resin layer in the recess slides on the sliding surface. Exposed to the moving surface, the rack bar slides between the porous metal sintered layer and the synthetic resin layer exposed in the recess of the inclined surface portion, so that an abrupt increase in sliding frictional resistance is prevented. It is possible to prevent deterioration in steering feeling due to an increase in dynamic frictional resistance.

  In a preferred example of the rack guide of the present invention, the recess of the inclined surface portion has a substantially circular shape in plan view.

  A plurality of recesses in the inclined surface portion having a substantially circular shape in plan view may be formed on each sliding surface (inclined surface portion), and in this case, the opening of the recess adjacent to the inclined surface portion is a multilayer. Preferably, the sliding surfaces of the sliding pieces are formed so as to overlap each other in the sliding direction of the rack bar. In such a case, in the sliding between the multilayer sliding piece and the rack bar, the sliding surface Since a lubricant or synthetic resin is always present along the sliding direction of the rack bar, a sudden increase in sliding frictional resistance is prevented.

  In a preferred example of the rack guide of the present invention, the recess of the inclined surface portion has a substantially square shape in plan view.

  The recess having a substantially square shape in plan view may be formed on the sliding surface of the multilayer sliding piece along the sliding direction of the rack bar or in a direction perpendicular to the sliding direction of the rack bar.

  In a preferred example of the rack guide of the present invention, the area ratio of the opening of the recess to the area of the inclined surface is 5 to 40%, preferably 10 to 30%.

  When the ratio of the area of the opening of the recess to the area of the sliding surface is less than 5%, a sufficient effect for reducing the sliding frictional resistance is not exhibited in sliding with the rack bar, and the area of the opening of the recess is not sufficient. When the ratio of the area to the area of the sliding surface exceeds 40%, the surface pressure (load per unit area) increases, and there is a possibility of promoting the wear of the synthetic resin layer.

  In a preferred example of the rack guide of the present invention, the rack guide base is made of any of iron-based sintered metal, aluminum, aluminum alloy, zinc, or zinc alloy.

  In the present invention, the recess of the rack guide base may be a through-hole, but may instead be a simple recess that is not penetrated, and the hollow portion of the hollow protrusion is open at both ends. However, instead of this, it may be open on the bottom side and closed on the other side.

  The rack and pinion type steering device of the present invention includes a gear case, a pinion rotatably supported by the gear case, a rack bar formed with rack teeth meshing with the pinion, and a slidably supported rack bar. The rack guide described above and a spring for pressing the rack guide toward the rack bar are provided.

  According to the present invention, it is possible to prevent a sudden increase in sliding frictional resistance even when the lubricant applied at the time of assembly has flowed out or depleted, and to prevent deterioration in steering feeling due to an increase in sliding frictional resistance. And a rack and pinion type steering apparatus including the rack guide.

  Next, embodiments of the present invention will be described in more detail based on examples shown in the drawings. The present invention is not limited to these examples.

  1 to 5, the rack guide 20 is formed of a rack guide base 30 and a multilayer sliding piece 40 integrally coupled to the rack guide base 30.

  The rack guide base 30 is formed of any one of iron-based sintered metal, aluminum, an aluminum alloy, zinc, or a zinc alloy. The rack guide base 30 has a cylindrical outer peripheral surface 31 on its outer surface, and a pair of flat surfaces 32 and 32 and a pair of flat surfaces 32 and 32 facing each other on one end side in the axial direction. A concave surface 35 having a pair of inclined surfaces 33 and 33 extending integrally opposite to each other and a bottom flat surface 34 integrally extending from the pair of flat surfaces 32 and 32, and the other of the other in the axial direction. A concave portion 36 is provided on the end side, and a through hole 37 as a concave portion is provided in the center of the flat bottom surface 34 of the concave surface 35.

  The multi-layer sliding piece 40 is covered and coated on a back metal 41 made of a steel plate, a porous metal sintered layer 42 integrally formed on the surface of the back metal 41, and the pores and the surface of the porous metal sintered layer 42. The synthetic resin layer 43 includes a pair of opposed inclined surface portions 43a and 43a, a pair of flat surface portions 44 and 44 continuous with the inclined surface portions 43a and 43a, and a bottom surface continuous with the flat surface portions 44 and 44, respectively. A portion 45 and a hollow protrusion 46 extending toward the back metal 41 at the center of the bottom surface 45 are provided.

  The steel plate as the back metal 41 constituting the multilayer sliding piece 40 is preferably a cold rolled steel plate (SPCC) having a thickness in the range of 0.5 to 1.5 mm.

  The porous metal sintered layer 42 is formed from a copper alloy having excellent frictional wear characteristics such as bronze, lead bronze, phosphor bronze, etc., but other than the copper alloy, for example, from an aluminum alloy or iron, depending on the purpose and application. It may be formed. In the porous metal sintered layer 42, the alloy powders and the alloy powder are firmly bonded to the back metal 41, and have a certain thickness and a required porosity. The thickness of the porous metal sintered layer 42 is usually 0.15 to 0.4 mm, preferably 0.2 to 0.3 mm, and the porosity is usually 10% by volume or more, preferably 15 to 40% by volume. It is.

  The synthetic resin layer 43 is preferably a synthetic resin composition containing a filler selected from ethylene tetrafluoride resin as a main component and selected from barium sulfate, magnesium silicate, phosphate, solid lubricant, and the like. It is. The thickness of the synthetic resin layer 43 is 0.05 to 0.15 mm from the surface of the porous metal sintered layer 42.

  The multi-layer sliding piece 40 is covered and coated on a back metal 41 made of a steel plate, a porous metal sintered layer 42 integrally formed on the surface of the back metal 41, and the pores and the surface of the porous metal sintered layer 42. It is formed by press-molding a multilayer sliding member comprising the synthetic resin layer 43.

  The pair of inclined surface portions 43a and 43a serve as sliding surfaces that slidably support the rack bar 8. The inclined surface portions 43a and 43a are formed with a plurality of recesses 47 that are circular in plan view.

  The recess 47 filled with the lubricant is recessed with a step between the back metal 41, the porous metal sintered layer 42, and the surface of the synthetic resin layer 43 in the thickness direction of the multilayer sliding piece 40. The recess 47 has a depth at which the upper surface (bottom surface of the step) 43b of the synthetic resin layer 43 coincides with the surface 42a of the porous metal sintered layer 42 (FIG. 5). A deep recess 47 may be used.

  The recesses 47 adjacent in the sliding direction A of the rack bar 8 are formed so as to overlap each other by δ in the sliding direction A of the rack bar 8 at the opening 48 thereof. The recess 47 has a total area ratio of 5 to 40% of the openings 48 of the plurality of recesses 47 occupying the area of the sliding surfaces (inclined surface portions 43a and 43a) that slidably support the rack bar 8. Preferably, it is formed to be 15 to 30%.

  The multi-layer sliding piece 40 having the above-described configuration is configured such that the hollow projecting portion 46 at the center of the bottom surface portion 45 is fitted into the through hole 37 at the center of the bottom flat surface 34 of the rack guide base 30, A rack guide 20 is formed together with the rack guide base 30 by being seated on the concave surface 35 of the rack 30, and the rack guide 20 is a hole extending in the lateral direction in the casing 3 (direction perpendicular to the moving direction of the rack bar 8). 9, the rack bar 8 is slidably supported.

  A plurality of recesses 47 are formed on the sliding surface (a pair of inclined surface portions 43a and 43a) of the multilayer sliding piece 40 of the rack guide 20, and the recess 47 occupying the sliding surface The total area ratio of the openings 48 is 5 to 40%, and the openings 48 of the recesses 47 are formed so as to overlap with each other in the sliding direction of the rack bar 8 by δ. In sliding between the sliding piece 40 and the rack bar 8, the lubricant supplied to the sliding surface including the recess 47 during the assembly is interposed between the sliding surface and the rack bar 8. The lubricant is always present along the sliding direction.

  The synthetic resin layer 43 wears on the sliding surface, and the sliding between the synthetic resin layer 43 and the rack bar 8 fills the porous metal sintered layer 42 and the pores of the porous metal sintered layer 42. Even when the resin and the rack bar 8 are shifted to sliding, the upper surface 43b of the synthetic resin layer 43 in the recess 47 is exposed on the sliding surface. The upper surface (bottom surface of the step) 43b of the synthetic resin layer 43 in the recess 47 is interposed therebetween. As a result, in the initial stage of sliding, a lubricant is interposed between the rack bar 8 and the sliding surface, and even when wear of the synthetic resin layer 43 on the sliding surface proceeds, the sliding surface has a recess. 47, the upper surface 43b of the synthetic resin layer 43 is exposed and interposed between the synthetic resin layer 43 and the rack bar 8, so that an increase in sliding frictional resistance is prevented, and deterioration in steering feeling due to an increase in sliding frictional resistance can be prevented. .

  6, 7 and 8 show another embodiment of the recess 47 formed in the sliding surface (the pair of inclined surface portions 43a and 43a) of the multilayer sliding piece 40. FIG.

  FIG. 6 shows a multilayer sliding piece 40 having a recess 47 having a long side in a direction orthogonal to the sliding direction A of the rack bar 8 on the sliding surface and facing each other. FIG. 7 shows that the sliding surface has a long side in a direction perpendicular to the sliding direction A of the rack bar 8 at a predetermined interval in the sliding direction A of the rack bar 8. The multilayer sliding piece 40 provided with the recessed part 47 of two planar view square shapes which oppose each other is shown.

  FIG. 8 shows a recess 47 having a rectangular shape in plan view that has a long side in the sliding direction A of the rack bar 8 on the sliding surface and is opposed to the direction orthogonal to the sliding direction A of the rack bar 8. The multilayer sliding piece 40 provided with this is shown.

  According to the rack and pinion steering device 1 including the rack guide 20 and the coil spring 11 that elastically presses the rack teeth 7 of the rack bar 8 against the pinion 6 through the rack guide 20, the rack bar 8 is slid. At least one recess 47 is formed in the sliding surface (the pair of inclined surface portions 43a and 43a) of the multilayer sliding piece 40 of the rack guide 20 that is movably supported. Since the lubricating oil such as grease that has been filled and applied is interposed, the rack bar 8 is smoothly guided by the handle operation. Further, since the recess 47 is formed with a step in the back metal 41, the porous metal sintered layer 42, and the synthetic resin layer 43 in the thickness direction of the multilayer sliding piece 40, the multilayer sliding piece. 40 and the rack bar 8 slide, wear of the synthetic resin layer 43 on the sliding surface of the multilayer sliding piece 40 proceeds, and the sliding between the synthetic resin layer 43 and the rack bar 8 is caused by the porous metal firing. Even when the synthetic resin filled in the pores of the binder layer 42 and the porous metal sintered layer 42 and the rack bar 8 are slid, the synthetic resin layer in the recess 47 is formed on the sliding surface. 43 is exposed to the sliding surface, and the rack bar 8 is filled in the porous metal sintered layer 42 and the pores of the porous metal sintered layer 42 on the sliding surface of the multilayer sliding piece 40. Since it slides with the synthetic resin and the upper surface 43b of the synthetic resin layer 43 exposed in the recess 47, a sudden sliding friction occurs. Increase of resistance is prevented, as a result, it is possible to prevent deterioration of the steering feeling due to the increase in sliding friction resistance.

It is sectional drawing which shows the rack guide of this invention. It is a top view of FIG. It is sectional drawing which shows the multilayer sliding piece in the rack guide of FIG. It is a partially enlarged view of a multilayer sliding piece. It is an expanded sectional view showing a recess. It is a top view which shows the other Example of a multilayer sliding piece. It is a top view which shows the other Example of a multilayer sliding piece. It is a top view which shows the other Example of a multilayer sliding piece. It is sectional drawing which shows a rack and pinion type steering device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rack pinion type steering device 6 Pinion 8 Rack bar 10, 20 Rack guide 30 Rack guide base | substrate 40 Multi-layer sliding piece 43a Inclined surface part 44 Flat surface part 45 Bottom surface part 46 Hollow protrusion part 47 Recessed part

Claims (6)

  A concave surface having a pair of flat surfaces opposing each other, a pair of inclined surfaces extending integrally from each of the pair of flat surfaces, and a bottom flat surface extending integrally from the pair of flat surfaces; The concave surface of the rack guide base body having a concave portion at the center of the flat bottom surface of the concave surface and having a cylindrical outer peripheral surface includes a back metal plate made of a steel plate, a porous metal sintered layer integrally formed on the surface of the back metal plate, The porous metal sintered layer comprises a pore and a synthetic resin layer filled and coated on the surface. The pair of opposed inclined surfaces, the pair of flat surfaces continuous to the inclined surfaces, and the flat surfaces are continuous. A multi-layer sliding piece having a bottom surface portion and a hollow projecting portion extending in the center of the bottom surface portion to the back metal side, the hollow projecting portion in the center of the bottom surface portion into a concave portion in the center of the bottom flat surface of the rack guide base. The inclined surface of the multilayer sliding piece that is fitted and seated Are formed with at least one recess having a step in the back metal, the porous metal sintered layer, and the synthetic resin layer in the thickness direction of the multilayer sliding piece. Is characterized in that the bottom surface of the step of the synthetic resin layer has a depth that matches at least the surface of the sintered porous metal layer, and the concave portion of the inclined surface portion is filled with a lubricant. Rack guide to be.   The rack guide according to claim 1, wherein the recess of the inclined surface portion has a substantially circular shape in plan view.   The rack guide according to claim 1, wherein the recess of the inclined surface portion has a substantially square shape in plan view.   The rack guide according to any one of claims 1 to 3, wherein an area ratio of the opening of the recess to an area of the inclined surface portion is 5 to 40%.   The rack guide according to any one of claims 1 to 4, wherein the rack guide base is made of any one of iron-based sintered metal, aluminum, an aluminum alloy, zinc, or a zinc alloy.   6. A gear case, a pinion rotatably supported by the gear case, a rack bar formed with rack teeth meshing with the pinion, and the rack bar slidably supported. A rack and pinion type steering apparatus comprising the rack guide described above and a spring that presses the rack guide toward the rack bar.

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