Bush for isolating stabilizer from vibration

A bush for isolating a stabilizer from vibration, is adapted to be fitted from the open end of an axle beam having a substantially U-shaped cross-section, to a stabilizer bar passing through the inside of the axle beam. The bush includes a fitting hole and an opening for guiding the bar into the fitting hole. The opening has a pair of first projections facing each other and a pair of second projections facing each other. When the opening becomes engaged with the bar, the first and second projections sequentially and individually contact with the bar and elastically deform in the direction in which the opening opens. When the fitting hole has engaged with the bar, the bush makes contact with the inner surface of the beam and elastically deforms in the direction in which the opening closes, and this causes the second projections to make contact with the first projections

TECHNICAL FIELD

The present invention relates to a bush adapted to be attached to a stabilizer bar in a vehicle suspension, for isolating a stabilizer from vibration.

BACKGROUND ART

In, for example, a rear suspension, there are structures in which the rear wheels are mounted on both ends of an axle beam which is long and narrow in the width direction of the vehicle, and a stabilizer bar bridges both ends of the axle beam. The cross-sectional shape of the axle beam is U-shaped. The stabilizer bar, which is a torsion bar, is arranged inside the axle beam.

While a vehicle is traveling and when the brakes are applied, the axle beam and stabilizer bar are subjected to some vibration. In order to suppress this vibration, an anti-vibration bush is fitted partway along the length of the axle beam. This technology is disclosed in Patent Document 1. Because the anti-vibration bush is fitted onto the stabilizer bar, it is known as a bush for isolating a stabilizer from vibration.

The bush for isolating a stabilizer from vibration disclosed in Patent Document 1 is an elastic element formed with a substantially C-shaped cross-section. This bush is introduced from the open end of an axle beam having a U-shaped cross-section, and fitted over the stabilizer bar. The outer peripheral surface of the fitted bush comes into contact with the inner surface of the axle beam in a compressed state. Vibration of the axle beam and the stabilizer bar is suppressed by the bush.

In order to fit a bush formed with a substantially C-shaped cross-section over a stabilizer bar, the opening in the bush has to be opened widely. Thus, a greater degree of flexibility allows the bush to be attached more securely on the axle beam and stabilizer bar. However, vibration must not cause an attached bush to come off the axle beam and stabilizer bar. Thus, the elastic element serving as the bush is preferably relatively hard.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF INVENTION

Technical Problem

An object of the present invention is to provide a technique allowing a bush for isolating a stabilizer from vibration to be more securely attached on an axle beam and stabilizer bar while also more effectively preventing the bush from coming off the axle beam and stabilizer bar.

Solution to Problem

According to the present invention, there is provided a stabilizer-vibration-isolating bush for isolating a stabilizer in a vehicle suspension from vibration, the bush being adapted to be inserted from an open end of an axle beam having a substantially U-shaped cross-section and extending in a vehicle width direction and to be engaged with a stabilizer bar passing through inside the axle beam, wherein the bush comprises a tubular elastic element which has an opening for engaging with the stabilizer bar and a fitting hole being in communication with the opening and adapted to be fitted over the stabilizer bar, characterized in that: the opening has a pair of first projections and a pair of second projections in a range from the fitting hole to an open end of the opening;

the first projections are positioned adjacent to the fitting hole and face each other; the second projections are positioned adjacent to the open end of the opening and face each other; the second projections and the first projections are formed so as to make sequential and individual contact with the stabilizer bar and so as to be individually capable of elastically deforming in a direction of opening of the opening as the opening engages with the stabilizer bar; and the elastic element is formed so as to make contact with a substantially U-shaped inner surface of the axle beam and elastically deform in a direction of closing of the opening, and thereby be capable of elastically deforming the second projections until the projections contact the first projections, when the fitting hole is fitted over the stabilizer bar.

Preferably, an opening width between the second projections is greater than an opening width between the first projections.

Desirably, each of the second projections has an inclined surface facing the open end of the opening, and the inclined surfaces are formed so as to move closer to each other while moving from the open end to the fitting hole.

In a preferred form, the first projections and the second projections are provided by a pair of grooves being formed in a pair of mutually opposing opening surfaces for constituting the opening, and the grooves are formed into a V-shaped cross-section.

Preferably, the elastic element has a pair of contact surfaces for making contact with an inner surface of the axle beam when fitted into the axle beam, and a pair of relief grooves positioned proximally to the contact surfaces and on the surface opposing the opening, and the relief grooves are formed so as to be capable of elastically deforming in a direction of absorbing error in the fitting dimensions of the contact surfaces with respect to the inner surface of the axle beam.

Desirably, when the fitting hole is fitted over the stabilizer bar, at least a portion of the elastic element in an area where contact is made with the substantially U-shaped inner surface of the axle beam is formed as an irregular surface.

Advantageous Effects of Invention

In the present invention, when the opening engages with the stabilizer bar, the pair of second projections is the first to come into contact with the stabilizer bar. This causes elastic deformation which opens the opening on the open end side approximately halfway. Afterwards, the pair of first projections come into contact with the stabilizer bar. This causes elastic deformation which opens the opening on the fitting hole side approximately halfway. Because the opening can be opened in two stages, the force used to open the opening (i.e., the force occurring when the opening engages with the stabilizer bar) is unexpectedly small. As a result, the bush for isolating the stabilizer from vibration can be fitted onto the stabilizer bar using a small amount of force. Also, an improvement is realized in regard to the bush for isolating the stabilizer from vibration being attached to the axle beam and the stabilizer bar.

When the fitting hole has been fitted over the stabilizer bar, the elastic element comes into contact with the substantially U-shaped inner surface of the axle beam and is elastically deformed in the direction closing the opening. This elastic deformation causes the pair of second projections to make contact with the pair of first projections. As a result, the pair of first projections adjacent to the fitting hole and the pair of second projections adjacent to the open end of the opening come into contact with each other when the fitting hole has been fitted over the stabilizer bar. The pair of first projections and the pair of second projections support each other so that any force acting on the other is stopped. For example, when force occurs in the direction for extracting the fitting hole from the stabilizer bar (extraction force), the extraction force causes elastic deformation which moves the pair of first projections toward the pair of second projections. However, because the pair of first projections is supported by the pair of second projections, the deformation is suppressed. Because the deformation of the pair of first projections is suppressed, it is difficult for the opening to open. This suppresses the bush for isolating the stabilizer from vibration from coming off with respect to the axle beam and the stabilizer bar.

The present invention thus allows the bush for isolating the stabilizer from vibration to fit better on the axle beam and stabilizer bar while also more effectively preventing the bush from coming off with respect to the axle beam and stabilizer bar.

In the present invention, the opening width between the pair of second projections is preferably set greater than the opening width between the pair of first projections. When the dimension from the base end of one second projection to the base end of the other second projection has been predetermined, the height of each one of the second projections can be reduced to the extent that the opening width between the pair of second projections is increased. When the second projections are inclined toward the first projections, it is difficult for second projections of a lower height to come into contact with the first projections even if the angle of inclination is fixed.

As mentioned above, when the opening engages with the stabilizer bar, the pair of second projections are the first to come into contact with the stabilizer bar. This causes elastic deformation which opens the open end of the opening by approximately half. Because the short second projections do not come into contact with the first projections when the second projections first come into contact with the stabilizer bar, the first projections are not affected. The pair of second projections can be sufficiently elastically deformed to open the opening on the open end side approximately halfway. This further improves the fit of the bush for isolating the stabilizer from vibration with respect to the stabilizer bar.

In the present invention, each of the pair of second projections has an inclined surface facing the open end of the opening. Preferably, the pair of inclined surfaces are formed so as to move closer to each other while moving from the open end to the fitting hole. Thus, the pair of inclined surfaces are tapered and become narrower from the open end to the fitting hole. When the opening is first engaged with the stabilizer bar, the pair of tapered surfaces makes contact with the stabilizer bar. At this time, the reaction force from the stabilizer bar sustained by the pair of inclined surfaces is divided into a horizontal force and a vertical force. The horizontal force is the reaction force in the direction of engagement, and the vertical force is the reaction force in the push open direction of the opening. Therefore, when the opening becomes engaged with the stabilizer bar, the vertical force can elastically deform the pair of second projections in the opening direction of the opening. Because the pair of inclined surfaces are pushed open by the vertical force, the fit of the bush for isolating the stabilizer from vibration with respect to the stabilizer bar is further improved.

In the present invention, the pair of first projections and the pair of second projections are preferably provided by the formation of a pair of grooves in a pair of opening surfaces facing each other to constitute the opening, and the pair of grooves have a V-shaped cross-section. The pair of second projections can be elastically deformed with the bottoms of the cross-sectionally V-shaped grooves serving as the pivot points. Because the bottoms of the cross-sectionally V-shaped grooves serve as the pivot points, elastic deformation of the grooves and the second projections is readily achieved. For example, when the fitting hole is fitted over the stabilizer bar, as mentioned earlier, the elastic element comes into contact with the substantially U-shaped inner surface of the axle beam and is elastically deformed in the closing direction of the opening. This closes the pair of grooves. Because the pair of grooves are cross-sectionally V-shaped grooves in this case, they are easily closed using the bottoms as the pivot points, and the closed state can be maintained. As a result, the pair of second projections easily continues to support the pair of first projections. Thus, the bush for isolating the stabilizer from vibration is more effectively suppressed from coming off with respect to the axle beam and the stabilizer bar.

In the present invention, the elastic element preferably has a pair of relief grooves. The pair of relief grooves can be elastically deformed in a direction of absorbing error in the fitting dimensions of the pair of contact surfaces with respect to the inner surface of the axle beam. Thus, any error in the fitting dimensions of the pair of contact surfaces due to variability in the manufacturing precision of the axle beam and the elastic element can be absorbed. For example, when the opening angle of an axle beam having a substantially U-shaped cross-section is narrow, elastic deformation of the pair of inclined surfaces towards each other facilitates fitting with the axle beam. Also, one type of elastic element (bush for isolating a stabilizer from vibration) can be prepared for axle beams having variability in their opening angles. This can improve the versatility of the bush for isolating a stabilizer from vibration.

In the present invention, an irregular surface is preferably formed in at least a portion in an area of the elastic element making contact with the substantially U-shaped inner surface of the axle beam when the fitting hole has been fitted over the stabilizer bar. Because the surface is irregular, the surface area making contact with the substantially U-shaped inner surface of the axle beam is small. This improves the fit of the bush for isolating the stabilizer from vibration with respect to the axle beam and the stabilizer bar.]

DESCRIPTION OF EMBODIMENTS

The following is a description of the mode for carrying out the present invention, made with reference to the appended drawings.

The following is a description made of a vehicle suspension using the anti-vibration bush in the first embodiment, with reference toFIG. 1throughFIG. 8. As shown inFIG. 1, a vehicle suspension10has a bush for isolating a stabilizer from vibration11, is positioned in the rear portion of the vehicle, and suspends the wheels31,

The suspension10includes an axle beam13(beam component13) which is long and narrow in the width direction of the vehicle, left and right arms24,25extending to the front and to the rear from both the left and right ends of the axle beam13, left and right link portions27,28provided on the front ends of the left and right arms24,25, and a stabilizer bar16bridging both ends of the left and right arms24,25. The left and right wheels31,32are rotatably supported at the rear ends of the left and right arms24,25.

This suspension10is a so-called axle beam suspension in which the wheels31,32are attached to both ends of the axle beam13, and a suspension bar16bridges both ends of the axle beam13.

When viewed from the width direction of the vehicle, as shown inFIG. 2andFIG. 3, the axle beam13has a nearly sideways U-shaped cross-section open on the front end or rear end. More specifically, the axle beam13is an integrated molded article made of an arcuate (crescent-shaped) base end17, a pair of upper and lower inclined plates18,18connected to the upper and lower ends of the arc of the base end17, and a pair of upper and lower horizontal plates19,19connected to the distal ends of the pair of inclined plates18,18.

As shown inFIG. 3, the radius of the inside of the base end17is Rb. The pair of upper and lower inclined plates18,18are positioned on a tangent of the arc of the base end17. The pair of upper and lower inclined plates18,18are formed so as to separate from each other as they move away from the upper and lower ends of the arc. The angle θ of the tapering in the pair of inclined plates18,18(tapering angle θ) is set as an acute angle, and is preferably set as approximately 60°. The tapering angle θ is the inner angle θ of the axle beam13or the tapering angle θ of the inner surface13aof the axle beam13. The range between the distal ends of the pair of horizontal plates19,19is open. As a result, the end13bof the axle beam13opposite the base end17is open. The opened end13bis referred to as open end13bbelow.

As shown inFIG. 3, the stabilizer bar16is composed of a round, bar-shaped torsion bar. It is positioned in the inner portion14(inner space14) of the axle beam13and extends along the axle beam13in the width direction of the vehicle. More specifically, the stabilizer bar16is positioned in the center between the pair of upper and lower inclined plates18,18. A horizontal straight line Cs extending in the front and rear directions of the vehicle through the center16aof the stabilizer bar16is referred to below as the axis Cs. The axle beam13is formed in a linearly symmetrical shape relative to the axis Cs. The diameter of the stabilizer bar16is smaller than the radius Rb of the inside of the base end17. A distance Lt from the bottom17aof the base end17to the center16aof the stabilizer bar16is greater than the radius Rb of the base end17. The axle beam13combined with the stabilizer bar16forms a beam assembly74.

As shown inFIG. 1andFIG. 2, at least one anti-vibration bush11is fitted partway along the length of the axle beam13. This bush for isolating a stabilizer from vibration11suppresses vibration of the axle beam13and vibration of the stabilizer bar16while, e.g., the vehicle is traveling or is under braking. Because the anti-vibration bush11is fitted over the stabilizer bar16, it is known as a bush for isolating a stabilizer from vibration. The anti-vibration bush11is referred to below as a bush for isolating a stabilizer from vibration11(abbreviated: bush11).

As shown inFIG. 3andFIG. 4, the bush11is a short, tubular elastic element with a uniform cross-sectional shape. The bush11is made out of a material such as rubber. More specifically, the tubular bush11has an overall profile that is substantially triangular when the tube is viewed lengthwise. The overall profile of the bush11is preferably a linearly symmetrical isosceles triangle relative to the axis Cs. The overall profile is more preferably an equilateral triangle within the frame of dotted lines. The equilateral triangle is linearly symmetrical relative to the axis Cs, and the stabilizer bar16is oriented to one vertex Pt positioned on the axis Cs. Because the inner angle θ of the axle beam13is set to 60°, a good fit is achieved and the angle is matched if the bush11has the shape of an equilateral triangle.

The three sides of a bush11whose overall profile is that of an equilateral triangle are composed of a first side36and a second side37mutually inclined with respect to the axis Cs, and a third side41perpendicular to the axis Cs as shown by the dotted lines. The vertex Pt is the point of intersection between the first side36and the second side37. Because the first side36is the first lateral surface of the bush11, it is appropriately referred to as the first lateral surface36below. Because the second side37is the second lateral surface of the bush11, it is appropriately referred to as the second lateral surface37below. Because the third side41is the third lateral surface of the bush11, it is appropriately referred to as the third lateral surface41below.

The bush11has a fitting hole42positioned in the approximate center of the equilateral triangle, and an opening45passing from the fitting hole42to the vertex Pt. This opening45opens the fitting hole42by creating a notch in the bush11from the fitting hole42to the vertex Pt. In other words, the fitting hole42and the opening45communicate with each other. Thus, the overall profile of a bush11having an opening45is that of both a substantially triangular shape and approximately the letter C when viewed lengthwise (in the length direction of the tube).

The fitting hole42and the opening45are positioned on the axis Cs, and pass through the bush11in the lengthwise direction. The fitting hole42is a perfectly round hole into which the round, bar-shaped stabilizer bar16is fitted. The diameter of the fitting hole42is substantially the same as the diameter of the stabilizer bar16. In other words, the diameter of the fitting hole42is set so that the entire inner peripheral surface of the fitting hole42makes close contact with the outer peripheral surface of the stabilizer bar16.

The opening45is an opening used for engaging the stabilizer bar16guidance into the fitting hole42. The opening45is formed in a shape which is linearly symmetrical with respect to the axis Cs. The overall profile of the opening45is substantially tapered, widening from the fitting hole42outward towards the vertex Pt. The minimum opening width w1of the opening45is smaller than the diameter of the fitting hole42.

As shown inFIG. 5, notches61,61are formed in a pair of upper and lower opening surfaces56,56which face each other to form the opening45. The pair of notches61,61are grooves having a bottom which are positioned so as to face each other. They have a V-shaped cross-section. In other words, a pair of inclined surfaces61a,61bform the V-shaped notch61. The opening angle of the pair of notches61,61can be either an acute angle or an obtuse angle, but an acute angle is preferred. The pair of notches61,61pass through the bush11in the lengthwise direction. In other words, the pair of notches61,61are formed along the direction of the fitting hole42. This pair of notches61,61are appropriately referred to as grooves61,61below.

In each opening surface56,56, the range from the fitting hole42to the open end45aof the opening45is divided by the pair of notches61,61(grooves61,61). As a result, the opening surfaces56,56are separated by the pair of notches61,61into a pair of first opening surfaces62a,62a, and a pair of second opening surfaces63a,63a. In other words, the opening surfaces56,56are divided in two lengthwise from the fitting hole42to the open end45aof the opening45by the notches61,61. The pair of first opening surfaces62a,62aare positioned adjacent to the fitting hole42and face each other. The pair of second opening surfaces63a,63aare positioned adjacent to the open end45aof the opening45and face each other.

The pair of second opening surfaces63a,63aand the pair of first opening surfaces62a,62aare formed so as to make sequential and individual contact with the stabilizer bar16and so as to be elastically deformable in the opening direction of the opening45individually when the opening45has engaged with the stabilizer bar16.

The following is a description of the first opening surface62a. By having a notch61formed in the first opening surface56, the notch61in the first opening surface56forms a first portion62close to the fitting hole42, and a second portion63close to the open end45aof the opening45. In other words, the first and second portions62,63may be regarded as portions which protrude from a bottom61cof the notch61toward the axis Cs as far as the first opening surface56. The first portion62is referred to as the first projection62, and the second portion63is referred to as the second projection63below. Because the second opening surfaces63a,63aare similar to the first opening surfaces62a,62a, further description has been omitted.

Thus, a pair of first projections62,62having first opening surfaces62a,62a, and a pair of second projections63,63having second opening surfaces63a,63aare formed in the opening45. The thickness of the first projections62,62and the second projections63,63is approximately half the overall thickness of from the fitting hole42to an open end15aof the opening45in the lengthwise direction of the opening.

The pair of first projections62,62are positioned adjacent to the fitting hole42and face each other. The pair of second projections63,63are positioned adjacent to the open end45aof the opening45and face each other. Thus, the opening45has a pair of first projections62,62, and a pair of second projections63,63in the range from the fitting hole42to the open end45aof the opening45.

The pair of second projections63,63and the pair of first projections62,62are formed so as to make sequential and individual contact with the stabilizer bar16and so as to be elastically deformable in the opening direction of the opening45individually when the opening45has engaged with the stabilizer bar16.

The first opening surfaces62a,62acan be parallel to the axis Cs. The opening width between the pair of upper and lower first projections62,62is w1, which is the same as the minimum opening width of the opening45. The opening width w2of the pair of upper and lower second projections63,63is greater than the opening width w1between the pair of upper and lower first projections62,62. Here, the opening width w2is the dimension separating the upper and lower second projections63,63from each other at their closest point.

The pair of second opening surfaces63a,63aare formed as inclined surfaces facing the open end45aof the opening45. The second opening surfaces63a,63aare inclined so as to come closer to each other as they move from the open end45atoward the fitting hole42.

More specifically, the pair of second opening surfaces63a,63aare inclined in two stages with respect to the axis Cs. The second opening surfaces63a,63aare composed of first inclined surfaces67,67, and second inclined surfaces68,68connected to the ends of the first inclined surfaces67,67. The first inclined surfaces67,67are inclined from the open end45aof the opening45toward the fitting hole42. The second inclined surfaces68,68are inclined from the ends of the first inclined surfaces67toward the fitting hole42.

Thus, each of the pair of second projections63,63has inclined surfaces67,67,68,68facing the open end45aof the opening45. The pair of first inclined surfaces67,67are inclined so as to come closer to each other as they move from the open end45atoward the fitting hole42. Similarly, the pair of second inclined surfaces68,68are inclined so as to come closer to each other as they move from the open end45atoward the fitting hole42.

The angle of inclination of the first inclined surface67with respect to the axis Cs is greater than the angle of inclination of the second inclined surface68with respect to the axis Cs. The pair of upper and lower first inclined surfaces67,67and the pair of upper and lower second inclined surfaces68,68are tapered and become narrower from the open end45aof the opening45toward the fitting hole42. The tapering angle of the taper in the upper and lower first inclined surfaces67,67is greater than the tapering angle of the taper in the upper and lower second inclined surfaces68,68.

As shown inFIG. 3, the bush11has a pair of first contact surfaces51,51, a pair of second contact surfaces52,52, a pair of recesses53,53, and a pair of relief grooves54,54(outer grooved portions54,54).

The pair of first contact surfaces51,51and the pair of second contact surfaces52,52make contact with the inner surface13aof the axle beam13when the bush11is fitted with respect to the axle beam13. One set of first and second contact surfaces47,48are formed along the first lateral surface36. The other set of first and second contact surfaces47,48are formed along the second lateral surface37. The pair of first contact surfaces51,51are positioned adjacent to the open end45aof the opening45. The pair of second contact surfaces52,52are positioned adjacent to the third lateral surface41.

The pair of recesses53,53are portions that arcuately recede into the bush11from the first and second lateral surfaces36,37. These are positioned between the pair of first contact surfaces51,51and the pair of second contact surfaces52,52. The pair of recesses53,53pass through the bush11in the lengthwise direction. Thus, the thickness of the bush11in the portions55,55(constricted portions55,55) between the fitting hole42and the pair of recesses53,53is smaller than the other portions. The pair of first projections62,62can be elastically deformed in the opening and closing directions of the opening45using the pair of constricted portions55,55as the pivot points.

The pair of relief grooves54,54are formed to enable elastic deformation in a direction which absorbs the error in the fitting dimensions of the pair of second contact surfaces52,52with respect to the inner surface13aof the axle beam13. More specifically, the pair of relief grooves54,54are positioned adjacent to the pair of second contact surfaces52,52and on the third lateral surface41(the surface41opposite the opening45). Also, the pair of relief grooves54,54are grooves having a bottom which open on the third lateral surface41and are oriented from the third lateral surface41toward the opening45. They are substantially parallel to the pair of second contact surfaces52,52. Also, the pair of relief grooves54,54are formed with mutual linear symmetry with respect to the axis Cs, and pass through the bush11in the lengthwise direction (seeFIG. 4).

The pair of relief grooves54,54are able to absorb any error in the fitting dimensions of the pair of second contact surfaces52,52due to variability in the manufacturing precision of the axle beam13and the bush11. For example, when the opening angle θ of the axle beam13having a substantially U-shaped cross-section is narrow, the bush can be easily fitted in the axle beam13by being elastically deformed in a direction which brings the pair of second contact surfaces52,52closer to each other. Also, one type of bush11can be prepared for axle beams13having variability in opening angles θ. This improves the versatility of the bush11.

However, as shown inFIG. 3andFIG. 5, the pair of second projections63,63can be elastically deformed in the opening and closing directions of the opening45using the bottom61c,61cof the pair of notches61as the pivot point. Thus, when the pair of first contact surfaces51,51are pushed toward the axis Cs, the pair of second projections63,63pivot on the bottom61c,61cof the notches61and are elastically deformed so as to close the opening45. As a result, the pair of notches61,61close. Afterwards, when the force pushing on the pair of first contact surfaces51,51is released, the pair of second projections63,63automatically return to their original state due to their own resilience. As a result, the pair of notches61,61open again. In this way, the pair of notches61,61can be opened and closed.

Because the bottom61c,61cof the notches61,61having a V-shaped cross-section serves as the pivot points, elastic deformation of the notches61and the second projections63,63is readily achieved. For example, as described above, when the fitting hole42is fitted over the stabilizer bar16, the bush11comes into contact with the substantially U-shaped inner surface13aof the axle beam13and is elastically deformed in the direction closing the opening45. This closes the pair of notches61,61. Because the pair of notches61,61are grooves having a V-shaped cross-section in this case, they are readily closed with the bottom61c,61cserving as the pivot points, and the closed state can be maintained. It is therefore easy for the pair of second projections63,63to continuously support the pair of first projections62,62. In this way, it is possible to suppress, in a more reliable manner, any incidence of the bush11coming off relative to the axle beam13and stabilizer bar16. The pair of notches61,61are referred to below as grooves61where appropriate.

The following is a description of the procedure for mounting a bush11having this configuration on the beam assembly74. First, as shown by arrow a1inFIG. 6A, the bush11is introduced from the open end13bof the axle beam13toward the stabilizer bar16.

Next, the position of the opening45of the bush11is harmonized with the stabilizer bar16. As mentioned above, the tapering angle of the tapering formed by the upper and lower first inclined surfaces67,67is large. As a result, it is easy to position the opening45with respect to the stabilizer bar16.

Next, when the bush11is pushed in and the opening45starts to become engaged with the stabilizer bar16, the first inclined surfaces67,67, each having the second projections63,63, make contact with and ride over the outer peripheral surface of the stabilizer bar16. At this time, as shown inFIG. 7, the reaction force fr sustained by the first inclined surface67from the stabilizer bar16is divided into a horizontal force fs and a vertical force fv. The horizontal force fs is the reaction force in the direction of engagement, and the vertical force fv is the reaction force in the direction which pushes open the opening45. Thus, when the opening45engaged with the stabilizer bar16, the second projections63can elastically deform under the vertical force fv in the opening direction of the opening45. Because the first inclined surface67is pushed open by the vertical force fv, the bush11is attached more securely on the stabilizer bar16. Because the action of the second inclined surfaces68described below is similar, the fitting operation is even easier.

Thus, as shown inFIG. 6A, the first inclined surfaces67,67, each of which having a second projection63,63, make contact with and ride over the outer peripheral surface of the stabilizer bar16, and are thereby pushed open by the outer peripheral surface. In other words, the second projections63,63elastically deform with the bottom61c,61cof the notches61,61serving as the pivot points so as to open the opening45. The notches61,61(grooves61,61) are opened in response to the deformation of the second projections63,63in the opening direction.

When the bush11is pushed in even further, as shown inFIG. 6B, the second inclined surfaces68,68of the second projections63,63are then pushed open by the outer peripheral surface of the stabilizer bar16. In other words, the second projections63,63elastically deform to further open the opening45. As described above, the tapering angle of the tapering formed by the upper and lower second inclined surfaces68,68is smaller than the tapering angle of the tapering formed by the upper and lower first inclined surfaces67,67. Because the tapering angle is small, the upper and lower second projections63,63can be easily pushed open.

Thus, only the second projections63,63are opened in the initial stage of the push-in operation. The first projections62,62taking up approximately half of the length of the opening45remain in the state prior to being introduced onto the stabilizer bar16. In other words, the force used to push in the bush11is an unexpectedly small force that elastically deforms and opens only the second projections63,63.

As shown inFIG. 6B, when the distal ends of the second projections63,63(second opening surfaces63a,63a) have ridden over the outer peripheral surface of the stabilizer bar16, the second projections63,63open no further. When the bush11is pushed in even further, the inclined surfaces of the upper and lower first projections62,62(the inclined surfaces61a,61aof the notches61,61) come into contact with and ride over the outer peripheral surface of the stabilizer bar16, pushing them open. As a result, the first projections62,62elastically deform with the constricted portions55,55serving as the pivot points, which opens the opening45.

Afterwards, when the bush11is pushed in even further, the distal ends of the upper and lower first projections62,62(the first opening surfaces62a,62a) come into contact with and ride over the outer peripheral surface of the stabilizer bar16. They are thus pushed open by the outer peripheral surface. In other words, the first projections62,62elastically deform so as to open the opening45even further. Thus, only the first projections62,62are opened in the latter stage of the push-in operation. The second projections63,63composing approximately half of the length of the opening45do not have to deform. In other words, the force used to push in the bush11is an unexpectedly small force that elastically deforms and opens only the first projections62,62.

While the first projections62,62are being pushed open by the outer peripheral surface of the stabilizer bar16, the first contact surfaces51,51come into contact with the inner surface13aof the axle beam13as shown inFIG. 6C. Accordingly, the first contact surfaces51,51are directed by the tapered inner surface13ain the closing direction (the direction approaching the axis Cs). As a result, the second projections63,63elastically deform using the bottom61c,61cof the notches61,61as the pivot points to close the opening45. At this time, the notches61,61are closed in response to the deforming of the second projections63,63in the closing direction. Thus, the second projections63,63deformed in the closing direction are not affected by the opening action of the first projections62,62.

Afterwards, when the bush11is pushed in even further, the distal ends of the first projections62,62(the first opening surfaces62a,62a) ride over the outer peripheral surface of the stabilizer bar16. With this, as shown inFIG. 6D, the first projections62,62return to their original state due to their own resilience. The fitting hole42is thus fitted over the stabilizer bar16.

In this state, the first contact surfaces51,51are guided in the closing direction (the direction approaching the axis Cs) by the base ends17of the closed arc of the axle beam13. As a result, the second projections63,63under prominent elastic deformation using the bottom61c,61cof the notches61,61as the pivot points to close the opening45. At this time, the notches61,61are closed in response to the deforming of the second projections63,63in the closing direction. As a result, the second projections63,63come into contact with the first projections62,62and are pressed as indicated by arrow a2. The task of mounting of the bush11on the axle beam13and the stabilizer bar16is then complete.

Thus, when the opening45engages with the stabilizer bar16, at first only the pair of second projections63,63(corresponding to the second opening surfaces63a,63a) come into contact with the stabilizer bar16, which elastically deforms them so as to open the opening45on the open end45aside approximately halfway. Afterwards, the pair of first projections62,62(corresponding to the first opening surfaces62a,62a) come into contact with the stabilizer bar16, which elastically deforms them so as to open the opening45on the fitting hole42side approximately halfway. In other words, because the thin first projections62,62and second projections63,63elastically deform separately, the deforming force is unexpectedly small. Because the opening45can be opened in two stages, the force opening the opening45, i.e., the force when the opening45engages with the stabilizer bar16, is also smaller than expected. As a result, the bush11can be fitted over the stabilizer bar16using a small force. The fit of the bush11with respect to the axle beam13and the stabilizer bar16is also improved.

However, as mentioned above, the opening width w2between the pair of second projections63,63is set so as to be larger than the opening width w1between the pair of first projections62,62. When the dimension from the base end of one second projection63to the base end of the other second projection63has been predetermined, the height of each one of the second projections63,63can be reduced to the extent that the opening width w2between the pair of second projections63,63is increased. When the second projections63,63are inclined toward the first projections62,62, it is difficult for the second projections63,63of a lower height to come into contact with the first projections62,62even if the angle of inclination is fixed.

As mentioned above, when the opening45engages with the stabilizer bar16, the pair of second projections63,63are the first to come into contact with the stabilizer bar16. This causes elastic deformation which opens the opening45on the open end45aside approximately halfway. Because the short pair of second projections63,63do not come into contact with the first projections62,62when the pair of second projections63,63are the first to come into contact with the stabilizer bar16, the first projections62,62are not affected. The pair of second projections63,63can be elastically deformed sufficiently to open the opening45on the open end45aside approximately halfway. This further improves the fit of the bush11with respect to the stabilizer bar16.

The outer peripheral surface of the fitted bush11makes contact with the inner surface13aof the axle beam13in a compressed state. Vibration of the axle beam13and the stabilizer bar16is suppressed by the anti-vibration bush11.

The following is a description of the force applied to remove the bush11from the beam assembly74. When the fitting hole42has been fitted over the stabilizer bar16as shown inFIG. 6D, the bush11comes into contact with the substantially U-shaped inner surface13aof the axle beam13and elastically deforms in the direction closing the opening45. This causes elastic deformation which causes the pair of second projections63,63to come into contact with the pair of first projections62,62. In other words, the pair of notches61,61(grooves61,61) are closed. As a result, when the fitting hole42has been fitted over the stabilizer bar16, the pair of first projections62,62adjacent to the fitting hole42and the pair of second projections63,63adjacent to the open end45aof the opening45come into contact with each other. In other words, the inclined surfaces61a,61aand the other inclined surfaces61b,61bcorresponding to the pair of notches61,61come into contact with each other as shown inFIG. 5. In the state shown inFIG. 6D, the elastic deformation of the pair of second projections63,63in the opening direction is restrained by the inner surface13aof the axle beam13. As a result, the pair of first projections62,62and the pair of second projections63,63support each other so as to stop the forces acting on each other.

Afterwards, when a force in the direction of extraction of the fitting hole42from the stabilizer bar16(extraction force) has been generated as indicated by arrow a3shown inFIG. 8, the movement of the first projections62,62in the extraction direction is restrained by the stabilizer bar16. Thus, the pair of first projections62,62elastically deform toward the pair of second projections63,63under the extraction force. However, because the pair of first projections62,62are supported by the pair of second projections63,63, the deformation is suppressed. Because the deformation of the pair of first projections62,62is suppressed, the opening45is difficult to open. As a result, the fitting hole42does not come away from the stabilizer bar16. It is therefore possible to suppress any incidence of the bush11coming off with respect to the axle beam13and stabilizer bar16. Also, neither a bonding agent nor a separate fixing component need to be used to suppress the bush11from coming off with respect to the axle beam13and the stabilizer bar16.

The following is a description of a bush for isolating a stabilizer from vibration11A of a second embodiment, made with reference toFIG. 9. The bush for isolating a stabilizer from vibration11A of the second embodiment is characterized by the formation of projections and recesses81on the pair of second contact surfaces52,52. The undulating projections and recesses81are arranged at a fixed pitch in the length direction of the bush for isolating a stabilizer from vibration11A. Because the rest of the configuration is similar to the configuration of the first embodiment shown inFIG. 1throughFIG. 7, further description has been omitted.

The following is a description of a bush for isolating a stabilizer from vibration11B in the third embodiment, made with reference toFIG. 10. The bush for isolating a stabilizer from vibration11B in the third embodiment is characterized by the formation of a plurality of small projections82on the pair of second contact surfaces52,52. The plurality of projections82can be conical, and are arranged in a staggered pattern on the pair of second contact surfaces52,52. Because the rest of the configuration is similar to the configuration of the first embodiment shown inFIG. 1throughFIG. 7, further explanation has been omitted.

Thus, the bush11A in the second embodiment and the bush11B in the third embodiment are characterized by the formation of an irregular surface in at least some (the pair of second contact surfaces52,52) of the portion (the pair of first contact surfaces51,51and the pair of second contact surfaces52,52) making contact with the substantially U-shaped inner surface13aof the axle beam13when the fitting hole42is fitted over the stabilizer bar16as shown inFIG. 2.

Because the pair of second contact surfaces52,52are uneven surfaces, the surface area making contact with the substantially U-shaped inner surface13aof the axle beam13is small. This improves the fit of the bush11with respect to the axle beam13and the stabilizer bar16. These bushes11A,11B also have the same operation and effect as the bush11in the first embodiment.

The bush11,11A,11B in the present invention can be used in either a rear suspension or front suspension.

Industrial Applicability

The bush for isolating a stabilizer from vibration11,11A,11B in the present invention is suitable for suppressing the vibration of an axle beam and stabilizer bar in the rear suspension of a vehicle.

List Of Reference Signs