JP3938766B2 - Compression coil spring - Google Patents

Description

  The present invention relates to a spring characterized by a spring structure and a spring mounting structure.

  2. Description of the Related Art Conventionally, for example, in a strut type suspension device used in an automobile or the like, a cylindrical shock absorber having a cylinder filled with oil and a piston received therein, and a compression provided to surround the cylinder type shock absorber There is an assembly in which an assembly including a coil spring is assembled so as to connect a vehicle body and a link member of a suspension device. However, since the input from the tire does not necessarily coincide with the axis of the shock absorber and is accompanied by a lateral load, a lateral load and a moment act on the sliding portion between the cylinder and piston of the shock absorber, resulting in a sliding resistance. As a result, the ride comfort of the car is impaired and the life of the shock absorber is shortened.

  In view of this, conventionally, the coil spring is offset to the axis of the shock absorber, and the lateral load and moment generated in the sliding portion between the shock absorber cylinder and the piston due to the lateral load and moment generated by the coil spring are reduced. Methods for reducing the moment are known. However, the offset amount is limited by the diameter of the coil spring, the installation space, and the like, and the lateral load and moment sufficient to completely cancel the lateral load and moment received by the input from the tire cannot be generated.

  Japanese Laid-Open Patent Publication No. 1-156119 proposes to reduce a lateral load and a moment generated in a sliding portion between a cylinder and a piston of a shock absorber by using a coil spring whose axis is curved in a free state. Has been. However, it is not clear how a bending coil spring can be held in the straightened state, and a bending coil spring suitable for a wheel suspension cannot be manufactured at low cost.

  In view of such problems of the prior art, a main object of the present invention is to provide a shock absorber for a shock absorber without increasing its size in a suspension device for a vehicle including a cylindrical shock absorber and a compression coil spring surrounding the shock absorber. An object of the present invention is to suitably reduce the sliding resistance generated between the cylinder and the piston.

  The second object of the present invention is to improve the ride comfort of the vehicle by suitably reducing the sliding resistance generated between the cylinder and the piston of the shock absorber in the above-described vehicle suspension system. It is to improve the durability.

  A third object of the present invention is a vehicle suspension system of the type described above, which does not increase the size of the apparatus and does not hinder the assembly workability, and does not interfere with the assembly of the shock absorber cylinder and piston. The purpose is to suitably reduce the dynamic resistance.

  A fourth object of the present invention is to provide a coil spring suitable for use in the vehicle suspension system as described above.

Such an object is, according to the invention, to provide a corresponding point on the strand for variations in length along the strand of the spring at a constant winding direction angular position for each turn along the vertical axis. The pitch angle given as the amount of change in height is maximized and minimized only once over almost the entire length of the coil, and each terminal forms a reference seat perpendicular to the axis. It is composed of a coiled coil spring, and is adapted to generate a lateral force perpendicular to the axis between both ends when the coil spring is expanded and contracted in the axial direction and compressed in the axial direction. This is achieved by providing a compression coil spring characterized in that:

  In particular, the lateral force generated in the coil spring acts between the piston and cylinder of the shock absorber due to a deviation between the acting direction of the load from the wheel and the axis of the shock absorber. If the lateral force is determined to be minimized, the sliding resistance caused by the lateral force generated between the shock absorber cylinder and the piston can be suitably reduced, improving the ride comfort of the vehicle, The durability of the absorber can be improved.

  If the coil spring wound along the inclined axis is maintained at a state having a vertical axis by applying a lateral initial load at both ends, and the coil spring is held so as to expand and contract in the vertical axis direction, the compression coil spring However, with the expansion and contraction, a lateral force can be generated between both ends, and a desired lateral force can be generated without increasing the size of the apparatus and without being subjected to geometric restrictions. can do. Also, the assembly workability is suitable, and the manufacturing cost is low.

  Alternatively, a coil spring wound along a vertical axis is held at both ends so as to maintain a state having an inclined axis by applying an initial load in the lateral direction and extending and contracting in the direction of the inclined axis, The same purpose can be achieved by holding a coil spring wound so that the pitch angle is periodically maximized and minimized along each axis so as to expand and contract in the vertical axis direction. Can do.

  Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a partially cutaway front view schematically showing a main part of a vehicle suspension device to which the present invention is applied. A strut assembly 4 having an upper end attached to the vehicle body 1 and a lower end attached to a link member 3 connecting the vehicle body 1 and the wheel carrier 2 is provided with a shock absorber 5 formed of a cylindrical oil damper, and the shock absorber 5 The compression coil spring 6 is held between the cylinder and the piston with spring seats 7 and 8. The upper spring seat 7 is pivotally attached to the vehicle body 1 via a rubber bushing or the like together with the upper end of the piston rod of the shock absorber 5, and the lower spring seat 8 is fixed to the outer periphery of the cylinder of the shock absorber 5. .

  Here, the compression coil spring 6 has a central axis B inclined at an angle θ as shown by an imaginary line in FIG. 2 in an unloaded state. In a state where both ends of the compression coil spring 6 are firmly held, a vertical load similar to that of a normal cylindrical coil spring is applied by applying a predetermined load in a direction opposite to each other in the lateral direction to elastically deform both ends. A shape having a central axis A can be obtained.

  As shown in FIG. 3, this compression coil spring 6 is inclined by an angle θ from its vertical axis A to the tilt axis B with a normal cylindrical coil spring obtained when deformed by applying a lateral load as a reference shape. Can be considered. That is, the compression coil spring having the vertical axis A in the orthogonal coordinate system defined by the X axis so that the vertical axis A is perpendicular to the Y axis and extends in the inclination direction of the inclination axis B. If an arbitrary point is given by coordinates (Sny, Snx), the corresponding point of the compression coil spring having the inclined axis B maintains the original coordinate Sny for the position in the Y direction, and the position in the X direction. Is given by shifting the original coordinate Snx in the X direction by an amount obtained by multiplying the coordinate Sny in the Y direction by tan θ, that is, as the coordinate (Snx + Sny · tan θ, Sny). The inclination θ of the central axis B of the compression coil spring 6 is determined according to the lateral load applied between the cylinder and the piston of the shock absorber 5 in the vehicle. Further, it is necessary to hold both ends of the coil spring 6 in a state where an initial lateral force and moment are applied, and it is necessary to make the spring seat suitable for it.

  In order to create such a spring, for example, a coil spring 6 as described above can be obtained by winding a strand of wire around a slanted cylindrical core bar at an equal pitch along the reference vertical axis. It is done. The outer periphery of the metal core may be smooth or may be provided with a spiral groove for guiding the strand. Such coiling is usually performed hot, and then a process such as tempering is performed.

Here, the sliding resistance F between the cylinder and the piston of the shock absorber 5 depends on the friction coefficient μ and the drag N,
F = μ · N
It is expressed. The drag N is a function of the lateral load vector Rsus applied between the cylinder and the piston of the shock absorber 5.

And the lateral load vector Rsus is
Rsus = Rgeo + Rcoil
It is expressed. Here, Rgeo is a geometric lateral load vector generated by the difference in the movement direction of the axle and the shock absorber 5 depending on the suspension structure, that is, the wheel support system, and Rcoil is a lateral load vector due to the inclination of the coil spring. is there. If this Rsus is reduced, the sliding resistance F is reduced. Therefore, Rcoil may be set to a size and direction so as to cancel Rgeo. That is, if other conditions are the same, Rcoil increases as the inclination of the central axis B of the spring 6 increases. Such a relationship can be solved analytically, but practically, it is better to solve by the finite element method (FEM), to perform an optimum design according to the application, and to wind the coil based on that.

  Here, in the above configuration, the spring 6 is tilted two-dimensionally. However, the spring 6 may be tilted three-dimensionally according to Rgeo, and may have a curved axis line in an unloaded state. Moreover, it is good also as a nonlinear spring from which a spring constant changes with expansion / contraction amounts.

  On the other hand, in place of the compression coil spring 6 having the axis B inclined in the free state as described above, as shown in an imaginary line in FIG. 4, as the second embodiment of the present invention, the vertical axis C in the free state is shown. It is also possible to use a normal cylindrical coil spring 16 having In this case, in use, both ends of the coil spring 16 are firmly held and a load is applied in the lateral direction so that the axis of the coil spring 16 is tilted by an angle θ as indicated by the tilt axis D. . Further, the coil spring 16 is used so as to expand and contract in the direction of the axis D. Also in this case, it is necessary to hold both ends of the coil spring 16 in a state where an initial lateral force and a moment are applied, and it is necessary to use a spring seat suitable for it.

  In order to create such a spring, a coiling machine is used as in the case of a normal cylindrical coil spring, and a cylindrical cored bar is rotated and a wire is wound around it at a constant pitch by a feeding device. Thus, the coil spring 16 as described above is obtained. Such coiling is usually performed hot, and then a process such as tempering is performed. Similarly to the above, the outer periphery of the metal core may be smooth or may be provided with a spiral groove for guiding the strand.

  5 to 7 show a third embodiment of the present invention. The compression coil spring 26 of this configuration has a shape as shown in FIG. 5 in an unloaded state. That is, in the no-load state, the center axis O is a straight line, the radius r is constant, and the pitch P is also constant pitch cylindrical coil spring, but the pitch angle (α) changes periodically with each winding. It is stipulated to do. The pitch angle (α) is given as the amount of change (ΔH) of the height (H) of the corresponding point on the strand relative to the variation (r · Δβ) of the length (r · β) along the strand of the spring. It is done. Here, β represents the rotation angle of the winding direction of the point on the element wire of the spring with respect to the central axis.

  In order to create such a spring, it is the same as in the case of a normal cylindrical coil spring. To create such a spring, a coiling machine is used as in the case of a normal cylindrical coil spring. If the wire is wound while being rotated while being fed in the vertical axis direction so that the pitch angle is periodically changed for each turn, the coil spring 26 is formed as described above. Such coiling is usually performed hot, and then a process such as tempering is performed. Similarly to the above, the outer periphery of the metal core may be smooth or may be provided with a spiral groove for guiding the strand.

  In FIG. 6, the horizontal axis is the number of nodes and the vertical axis is the spring height (H) when 20 nodes are provided per revolution (360 °) along the wire of the coil spring. A graph is shown. In the case of a normal coil spring, as indicated by a broken line B, the height of the corresponding point on the strand with respect to the number of nodes, that is, the rotation angle (β) in the winding direction of the point on the spring strand. (H) increases proportionally. On the other hand, in the case of the coil spring shown in FIG. 5, as indicated by the solid line A, the number of nodes, that is, the rotation angle (β) of the point on the spring strand is on the corresponding strand. The height (H) of the point periodically increases or decreases with respect to the level of the broken line B every 180 °.

  FIG. 7 shows a graph in which nodes are defined similarly, the horizontal axis is the number of nodes, and the vertical axis is the pitch angle (α). As shown by this graph, the pitch angle (α) of the coil spring is 180 as indicated by the solid line A with respect to the number of nodes, that is, the rotation angle (β) of the winding direction of the point on the wire of the coil spring. The maximum and minimum are repeated in order for each degree. That is, one peak and one valley of the pitch angle (α) appear between one volume (20 nodes in the figure). When the coil spring 26 is compressed, a lateral force is generated in a specific direction between both ends. The coil spring 26 is attached so that the lateral force acts in a direction against a lateral load generated in the shock absorber 5.

  The lateral force generated at each end of the coil spring 26 increases as the amplitude of the pitch angle α (W in FIG. 7) increases. The amount is determined according to the lateral load applied between the cylinder and the piston of the shock absorber 5 in the vehicle. The structure of the coil spring 26 has the same geometric structure as that of the coil spring 6 shown in FIG. 4, but the coil spring 26 has a reference seating surface at the end of the spring with respect to the compression direction of the spring. Is perpendicular to the equi-pitch direction (A) of the spiral of the wire, and is inclined at an angle θ with respect to the central axis (B) of the spring.

  Further, in the above configuration, the spring 26 is configured such that the pitch angle (α) periodically repeats the maximum and the minimum in the diameter direction, that is, the angle between the maximum and the minimum is the same. In this case, for example, the maximum and minimum values can be arbitrarily set at a winding direction angle (β) position that is offset with respect to the diameter direction so as to form 160 ° with each other.

  The present invention can be applied not only to a cylindrical coil spring, but also to a conical coil spring, a drum coil spring, a barrel coil spring, a taper coil spring, and the like. In FIG. 7, in addition to a cylindrical coil spring (dashed line A) whose pitch angle is periodically increased and decreased and a cylindrical coil spring having a constant pitch angle (dashed line B), as shown in FIG. Also shown is the relationship between the nodes, i.e., the winding direction angle (β) and the pitch angle (α). For example, in the case of a conical coil spring having an equal pitch, since the increment of the axial distance for each turn is constant, as indicated by the broken line C, the number of spring nodes, that is, the number of turns increases. The pitch angle (α) gradually increases. In the case of a conical coil spring in which the pitch angle increases and decreases periodically, the number of nodes of the spring, that is, the winding direction angle (β, as shown by a two-dot chain line D, which is given as a combination of the broken line A and the broken line C, ) Increases, the pitch angle periodically increases and decreases, and the amplitude increases.

  As is apparent from the above description, according to the vehicle suspension device of the present invention, the vehicle suspension device having the cylindrical shock absorber and the compression coil spring surrounding the shock absorber between the vehicle body and the wheel. In this case, the compression coil spring is a spring that generates a load in a direction against the lateral load generated in the shock absorber due to the compression, so that the sliding resistance between the cylinder and the piston due to the lateral load generated in the shock absorber is reduced. Can be reduced or completely offset, and the apparatus is not increased in size.

While there has been described about the shape condition of a preferred embodiment of the present invention, those skilled in the art without departing from the claims of the present invention will be made with various modifications.

It is a partially broken partial front view showing typically the principal part of the suspension system for vehicles to which the present invention was applied. It is a figure which shows only the spring of the suspension system for vehicles to which this invention was applied. It is a schematic diagram explaining the spring of FIG. It is a figure which shows only the spring of the suspension system for vehicles in another embodiment to which this invention was applied. It is a figure which shows only the spring of the suspension apparatus for vehicles in another embodiment with which this invention was applied. It is a graph which shows the relationship between the node (angle) of a coil spring, and spring height (H). It is a graph which shows the relationship between the node (angle) of a spring, and a pitch angle ((alpha)).

Claims (2)

The pitch angle given as the change in the height of the corresponding point on the strand relative to the variation in length along the strand of the spring, at a constant winding direction angular position for each turn along the vertical axis, It consists of a coil spring wound so as to become a maximum and a minimum only once over substantially the entire length of the coil and so that each end forms a reference seat surface perpendicular to the axis,
A compression coil, wherein the coil spring is expanded and contracted in the axial direction, and is adapted to generate a lateral force perpendicular to the axis between both ends when compressed in the axial direction. Spring. The compression coil spring according to claim 1, wherein the coil spring has a true cylindrical shape in a substantially unloaded state.

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