JP2012057777A - Suspension device and coil spring for suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of controlling a lateral force generated in a coil spring.SOLUTION: A suspension device 10 connects between a vehicle body side member and a wheel side member of a vehicle. The suspension device 10 includes a coil spring 20, an upper sheet 36 abutting against an upper end portion of a winding of the coil spring 20, and a lower sheet 42 abutting against a lower end portion of the wiring of the coil spring 20. When a rated load acts on the coil spring 20, an end turn portion of at least either the upper end portion or lower end portion of the winding of the coil spring has a first wire diameter portion, and a second wire diameter portion smaller in wire diameter than the first wire diameter portion.

Description

  The present specification relates to a suspension device for connecting a vehicle body side member and a wheel side member of a vehicle, and a coil spring used in the suspension device.

  In a suspension device used for a vehicle such as an automobile, a coil spring is usually disposed between a vehicle body side member and a wheel side member. In the coil spring used in this type of suspension device, the load action line is usually eccentric from the coil axis. For this reason, when the coil spring expands and contracts, a lateral force (that is, a force perpendicular to the coil axis of the coil spring) is generated in the coil spring. In this type of suspension device, there is a demand for controlling the lateral force generated in the coil spring. For example, in a strut type suspension device used in an automobile or the like, a load input shaft to the suspension device is displaced from a strut shaft of a shock absorber (strut), and therefore a bending moment acts on the shock absorber. When a bending moment acts on the shock absorber, the smooth expansion and contraction of the shock absorber is hindered, and the ride comfort and handling / stability (so-called stability) is deteriorated. For this reason, if the bending moment which acts on a shock absorber can be reduced using the lateral force which generate | occur | produces in a coil spring, riding comfort and maneuverability can be improved. However, if the magnitude and direction of the lateral force generated in the coil spring is not appropriate, the bending moment acting on the shock absorber cannot be reduced, and the bending moment acting on the shock absorber is increased. Thus, a technique for controlling the lateral force generated in the coil spring has been developed (for example, Patent Document 1).

JP 2000-94920 A

  In the technique of Patent Document 1, the lateral force generated in the coil spring is controlled by bending the coil axis of the coil spring. For this reason, in the case where a sufficient space for arranging the coil springs cannot be ensured, there arises a problem that the coil springs and peripheral parts interfere with each other by bending the coil shaft.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique capable of controlling the lateral force generated in the coil spring without bending the coil shaft.

  The suspension device of the present application connects the vehicle body side member and the wheel side member of the vehicle. This suspension device has a coil spring, an upper seat that is disposed on the vehicle body side and abuts on the upper end portion of the coil spring winding, and a lower seat that is disposed on the wheel side and abuts on the lower end portion of the coil spring winding. is doing. When a reference load is applied to the coil spring, at least one end winding portion of the coil spring winding has a wire diameter larger than that of the first wire diameter portion and the first wire diameter portion. It has a small second wire diameter part.

  Here, the above-mentioned “reference load” means a load applied to the coil spring when the vehicle is stationary on a horizontal plane. In the case of a vehicle in which the load weight changes, the “reference load” changes depending on the load weight of the vehicle. For this reason, a load acting on the coil spring when an object having a preset load weight is placed on the vehicle is referred to as a “reference load”.

  In the above suspension device, when a reference load is applied to the coil spring, the first wire diameter portion having a large wire diameter and the wire diameter are formed on either the upper end portion or the lower end portion of the coil spring winding. A small second wire diameter portion is formed. For this reason, the contact force between the winding of the coil spring and the sheet changes depending on the positions of the first wire diameter portion and the second wire diameter portion, and a lateral force corresponding to the position is generated in the coil spring. Therefore, by adjusting the positions and lengths of the first wire diameter portion and the second wire diameter portion, the magnitude and direction of the lateral force generated in the coil spring can be controlled without bending the coil shaft. .

  In the above suspension device, other conventional techniques for controlling the lateral force of the coil spring can be used together. For example, the coil axis of the coil spring may be curved, the coil diameter of the coil spring may be changed in the direction of the coil axis, or the winding pitch of the coil spring may be changed. By combining these, the lateral force generated by the coil spring can be controlled in a wider range.

The above-described suspension device can be realized as a strut-type suspension device. In other words, the suspension device may further include a shock absorber that is disposed inside the coil spring and has an upper end connected to the vehicle body side member and a lower end connected to the wheel side member. The upper seat is fixed to the vehicle body side member, and the lower seat is fixed to the shock absorber. The first wire diameter portion and the second wire diameter portion are arranged so that the lateral force generated by the coil spring is in a direction to cancel the bending moment acting on the shock absorber by the external force acting on the wheel from the road surface. Yes.
According to such a configuration, the bending moment acting on the shock absorber is canceled out by the lateral force generated by the coil spring. For this reason, the smooth expansion-contraction operation | movement of a shock absorber is securable.

  In the above suspension device, the coil spring can be a cylindrical coil spring. By using the cylindrical coil spring, the coil spring can be easily manufactured.

  The present specification also discloses a novel coil spring for a suspension device that can control a lateral force generated in the coil spring. A coil spring for a suspension device disclosed in the present specification is disposed between a pair of seats respectively arranged on a vehicle body side and a wheel side in a suspension device that connects between a vehicle body side member and a wheel side member of a vehicle. The At least one of the upper end portion and the lower end portion of the coil spring winding has a first wire diameter portion and a second wire diameter portion having a smaller wire diameter than the first wire diameter portion.

The side view of the suspension apparatus 10 which concerns on this embodiment. The graph which shows the relationship between the winding number from the upper end of the winding of the coil spring which concerns on an Example, and a wire diameter. The top view from the upper end of the winding of the coil spring which concerns on an Example to the 1st roll. The figure which shows the calculation result which computed the contact force generate | occur | produced between the winding of the coil spring which concerns on an Example, and an upper sheet | seat. The graph which shows the relationship between the winding number from the upper end of the winding of the coil spring which concerns on a comparative example, and a wire diameter. The figure which shows the calculation result which computed the contact force generate | occur | produced between the winding of the coil spring which concerns on a comparative example, and an upper sheet | seat. Each load eccentric position on the upper end side (upper seat surface) and lower end side (lower seat surface) when the wire diameter of the coil at the upper end of the coil spring is changed (the wire diameter is changed in the figure), and the coil Load eccentric positions of the upper end side (upper seat surface) and lower end side (lower seat surface) when the wire diameters of the upper and lower ends of the spring are not changed (the wire diameter is not changed in the figure) FIG.

  As shown in FIG. 1, the suspension device 10 of this embodiment is a strut type suspension device that connects a vehicle body side member (not shown) and a wheel side member (not shown) of an automobile. The suspension device 10 includes a shock absorber 30, a coil spring 20, an upper seat 36, and a lower seat 42.

  The shock absorber 30 functions as a wheel positioning strut (strut) (not shown). The shock absorber 30 includes a cylinder 40 and a piston rod 34. The cylinder 40 has a cylindrical shape. A viscous fluid (for example, oil) is enclosed in the cylinder 40. The lower end of the cylinder 40 is fixed to a wheel side member (not shown). The lower end of the piston rod 34 is inserted into the upper end of the cylinder 40. The piston rod 34 is assembled to the cylinder 40 so as to be able to advance and retract. When the piston rod 34 moves back and forth with respect to the cylinder 40 (that is, when the shock absorber 30 expands and contracts), the viscous force of the viscous fluid sealed in the cylinder 40 acts on the piston rod 34. The upper end of the piston rod 34 is fixed to the vehicle body side member.

  A coil spring 20 is disposed outside the shock absorber 30. That is, it can be said that the shock absorber 30 is disposed inside the coil spring 20, and the shock absorber 30 penetrates the inside of the coil spring 20. The coil spring 20 is constituted by a winding wound spirally around a coil axis. In the present embodiment, the coil spring 20 is a cylindrical coil spring having an equal pitch. The entire surface of the coil spring 20 is coated with resin (paint). The coil axis of the coil spring 20 coincides with the axis of the shock absorber 30 (that is, the axis of the piston rod 34 and the cylinder 40).

  The upper end 22 of the coil spring 20 is in contact with the lower surface of the upper sheet 36. The lower end 24 of the winding of the coil spring 20 abuts on the upper surface of the lower seat 42. That is, the coil spring 20 is disposed between the upper seat 36 and the lower seat 42. The upper seat 36 has a disc shape and is fixed to the upper end of the piston rod 34. Since the upper end of the piston rod 34 is fixed to the vehicle body side member, the upper seat 36 is also fixed to the vehicle body side member. The lower seat 42 has a disc shape and is fixed to the cylinder 40. Since the lower end of the cylinder 40 is fixed to the wheel side member, the lower seat 42 is also fixed to the wheel side member.

  As shown in FIG. 1, the suspension device 10 is attached with a central axis 50 (an axis common to the piston rod 34, the cylinder 40, and the coil spring 20) inclined around the Y axis. When the load applied upward to the lower seat 42 is increased, the coil spring 20 is compressed and the piston rod 34 slides with respect to the cylinder 40 so that the lower seat 42 is located on the upper seat 36 side (upper side) along the Z-axis direction. ) When the load applied upward to the lower seat 42 decreases, the coil spring 20 extends and the piston rod 34 slides with respect to the cylinder 40, and the lower seat 42 is opposite to the upper seat 36 along the Z-axis direction (lower side). To the side). By the operation of the coil spring 20 and the shock absorber 30 as described above, the impact when the wheel gets over the protrusion on the road surface or the like is absorbed, and a comfortable riding comfort can be realized.

  In the above suspension device 10, when the magnitude of the load acting on the coil spring 20 changes, an end winding portion (a portion not functioning as a spring) and an effective winding portion (spring) at the upper end portion 22 of the winding of the coil spring 20. The position of the boundary of the part that functions as) changes. Similarly, also at the lower end portion 24 of the winding of the coil spring 20, when the magnitude of the load acting on the coil spring 20 changes, the position of the boundary between the end winding portion and the effective winding portion changes. When the boundary between the end winding portion and the effective winding portion changes in the upper end portion 22 and the lower end portion 24 of the coil spring 20, the lateral force generated in the coil spring 20 also changes accordingly. Therefore, when designing the coil spring 20, it is necessary to decide what kind of lateral force is to be generated in what kind of state. Therefore, in the present embodiment, the reference state is set within the operating range of the suspension device 10 and is designed so that a desired lateral force is generated in the coil spring 20 in the reference state. That is, in the present embodiment, a state where the vehicle is stationary on a horizontal plane is referred to as a “reference state”, and a load applied to the coil spring 20 in the “reference state” is referred to as a “reference load”. Note that the “reference load” acting on the coil spring 20 in the “reference state” varies depending on the weight of the vehicle body including the loaded weight. For this reason, in this embodiment, when the number of passengers is two, the load applied to the coil spring 20 is set as the “reference load”. The “reference state” can be set as appropriate within the operating range of the suspension device 10 according to the characteristics required of the vehicle. In addition, the “reference load” can be set to a load at another loaded weight according to the use of the vehicle (truck, private car, etc.).

  In the suspension device 10, when a reference load is applied to the coil spring 20, at least one end winding portion of the upper end portion 22 and the lower end portion 24 of the coil spring 20 has a first wire diameter portion and a first wire diameter portion. Also has a second wire diameter portion with a small wire diameter. And since a 2nd wire diameter part has a wire diameter smaller than a 1st wire diameter part, it becomes difficult to contact a sheet | seat (36 or 42) compared with a 1st wire diameter part. Thereby, the contact force generated between the coil spring 20 and the seat (36 or 42) changes according to the positions and sizes of the first contact portion and the second contact portion. Therefore, the magnitude and direction of the lateral force generated in the coil spring 20 can be controlled by appropriately designing the positions and sizes of the first contact portion and the second contact portion.

  As described above, in the suspension device 10, the shock absorber 30 functions as a wheel positioning strut (strut) (not shown). As a result, the load input shaft to the suspension device 10 is deviated from the central shaft 50 of the shock absorber 30, and a bending moment is applied to the shock absorber 30 by an external force acting on the wheel from the road surface. Therefore, in the present embodiment, the lateral force generated in the coil spring 20 when a reference load is applied to the coil spring 20 is in a direction in which the bending moment acting on the shock absorber 30 is canceled by the external force acting on the wheel from the road surface. In addition, the positions and sizes of the first wire diameter portion and the second wire diameter portion are set. As a result, a smooth sliding operation of the piston rod 34 of the shock absorber 30 is possible, and it is possible to suppress deterioration in riding comfort and maneuverability.

  Here, it is an actual example that the lateral force of the coil spring 20 can be controlled by forming the first wire diameter portion and the second wire diameter portion at the upper end portion 22 and / or the lower end portion 24 of the winding of the coil spring 20. I will give a description. 2-4 is a figure for demonstrating the Example which formed the 1st wire diameter part and the 2nd wire diameter part in the upper end part 22 of the coil spring 20. FIG. 5 and 6 are diagrams for explaining a comparative example in which the wire diameter of the upper end portion of the coil spring is constant.

  As shown in FIGS. 2 and 3, at the upper end 22 of the coil spring 20, the wire diameter of 0.0 to 0.1 turns (range A in FIG. 3) is constant at 6.0 mm, The wire diameter of the 0.2th roll (the range of B in FIG. 3) gradually changes from 6.0 mm to 10.0 mm, and the wire diameter of the 0.2 to 0.4th roll (the range of C in FIG. 3). Becomes constant at 10.0 mm, and the wire diameter of the 0.4th to 0.5th rolls (range D in FIG. 3) gradually changes from 10.0 mm to 6.0 mm. The wire diameter of the eye (range E in FIG. 3) is constant at 6.0 mm, and the wire diameter of the 0.65-0.7th roll (range F in FIG. 3) gradually increases from 6.0 mm to 10.0 mm. The wire diameter of the 0.7-1.0th roll (range G in FIG. 3) is constant at 10.0 mm. Therefore, in this embodiment, the 0.2-0.4th roll (range C in FIG. 3) and the 0.7-1.0th roll (range G in FIG. 3) are the first wire diameter portions. The 0.0-0.1th roll (the range of A in FIG. 3) and the 0.5-0.65th roll (the range of E in FIG. 3) are the second wire diameter portions. In addition, the 0.1-0.2th roll (range of B of FIG. 3), the 0.4-0.5th roll (range of D of FIG. 3), and the 0.65-0.7th roll (FIG. 3). The range of F) is a connection portion for connecting the first wire diameter portion and the second wire diameter portion.

  When a reference load is applied to the coil spring 20, the 0.0 to 0.7 turns of the upper end portion 22 of the coil spring 20 become end turns, and the portion exceeding the 0.7 turn is effective winding. Part. Further, in the end winding portion, the first wire diameter portion contacts the upper sheet 36, and the second wire diameter portion and the contact portion are not in contact with the upper sheet 36. As shown in FIG. 4, when the reference load is applied to the coil spring 20, the contact force generated between the coil spring 20 and the upper sheet 36 is 0.2 roll, 0.4 roll, 0. A peak occurs at the seventh volume. That is, of the windings of the coil spring 20, a peak occurs in the contact force at the boundary between the connection portion and the first wire diameter portion. Therefore, by controlling the position of the boundary between the connecting portion and the first wire diameter portion, that is, by controlling the position of the second wire diameter portion, a peak of contact force is generated between the coil spring 20 and the upper seat 36. The position to do can be controlled.

  On the other hand, as shown in FIG. 5, the coil spring of the comparative example has a constant wire diameter of 10.0 mm. In addition, when a reference load is applied to the coil spring of the comparative example, the 0.0 to 0.6 turns of the upper end of the coil spring become the end winding part (the part in contact with the upper sheet), and 0.6 turns The part beyond the eyes is an effective winding part. As shown in FIG. 6, when a reference load is applied to the coil spring of the comparative example, the contact force generated between the coil spring 20 and the upper sheet 36 has a peak at the 0.1th to 0.15th turns. .

  As is apparent from FIGS. 2 to 6, in the coil spring 20 of the embodiment, the first wire diameter portion and the second wire diameter portion are formed at the upper end portion 22 of the winding, so that the comparative example of FIGS. As compared with the above, the position where the peak of the contact force occurs between the coil spring 20 and the upper sheet 36 and the magnitude of the contact force are changed. Thereby, as shown in FIG. 7, the load eccentricity from the coil center of the coil spring 20 also changes. That is, with respect to the load eccentric position Δ on the upper end side of the coil spring of the comparative example (the winding wire diameter is constant), the load eccentric position ○ on the upper end side of the coil spring of the embodiment is directed toward the center in the x direction. The y direction is slightly moved outward. This also applies to the lower end portion of the coil spring 20. That is, the load eccentric position ● on the lower end side of the coil spring of the embodiment is directed toward the center in the x direction with respect to the load eccentric position ▲ on the lower end side of the coil spring of the comparative example (the wire diameter of the winding is constant). The y direction is moving outward. Therefore, by forming the first wire diameter portion and the second wire diameter portion at the upper end portion of the coil spring, the load eccentric positions of the upper end portion and the lower end portion of the coil spring can be changed. When the load eccentric positions of the upper end portion and the lower end portion of the coil spring change, the magnitude and direction of the lateral force generated in the coil spring also change. Therefore, the magnitude and direction of the lateral force generated in the coil spring can be controlled by controlling the position and length of the first wire diameter portion and the second wire diameter portion formed at the upper end portion of the coil spring.

  As is clear from the above description, by forming the first wire diameter portion and the second wire diameter portion at one end of the coil spring, the load eccentric position is changed at both ends of the coil spring, thereby the coil spring. The magnitude and direction of the lateral force generated in For this reason, even if the first wire diameter portion and the second wire diameter portion are formed at the lower end of the coil spring, the magnitude of the lateral force generated in the coil spring can be changed. Further, even if the first wire diameter portion and the second wire diameter portion are formed at the upper end and the lower end of the coil spring, the magnitude of the lateral force generated in the coil spring can be changed. Therefore, a desired lateral force can be generated from the coil spring by appropriately forming the first wire diameter portion and the second wire diameter portion at the upper end and / or the lower end of the coil spring.

  As described above, in the suspension device 10 according to the present embodiment, the end winding portion of the upper end portion 22 of the coil spring 20 has the first wire diameter portion and the second wire diameter portion, and thus is generated in the coil spring 20. Control the magnitude and direction of the lateral force. For this reason, it is not necessary to bend the axis of the coil spring 20, and the arrangement space of the suspension device 10 can be reduced.

  Further, in the above-described suspension device 10, since it is only necessary to form the first wire diameter portion and the second wire diameter portion at the end portion of the coil spring 20, the coil spring 20 can be a cylindrical coil spring having an equal pitch. . For this reason, compared with the case where a coil axis | shaft is curved, the coil spring 20 can be manufactured by a simple method.

  Further, in the suspension device 10 of the above-described embodiment, a region in which the wire diameter gradually changes between the first wire diameter portion and the second wire diameter portion (connection region (regions B, D, and F in FIG. 3)). ) So that the cross section of the coil spring does not change abruptly. This prevents stress concentration from occurring in the coil spring.

  In the above-described embodiment, the first wire diameter portion and the second wire diameter portion are provided at the end of the coil spring. However, the technique disclosed in this specification is not limited to such a form, and is generated in the coil spring. It can be designed as appropriate according to the lateral force desired. For example, a third wire diameter portion having a wire diameter different from the wire diameter of the first wire diameter portion and different from the wire diameter of the second wire diameter portion may be formed at the end of the coil spring.

  Furthermore, in the above-described embodiment, the cylindrical coil spring having a straight coil axis is used, but the technology disclosed in the present specification is not limited to this. For example, the coil shaft may be curved, and the shape of the coil spring may be a conical shape, a one-sided drawing shape, a drooping shape, a pinching shape, or the like, or the winding pitch of the coil spring changes. It may be a thing.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

10: Suspension device 20: Coil spring 22: Upper end 24: Lower end 30: Shock absorber 34: Piston rod 36: Upper seat 40: Cylinder 42: Lower seat 50: Center shaft

Claims (4)

A suspension device for connecting a vehicle body side member and a wheel side member of a vehicle,
Coil springs,
An upper seat arranged on the vehicle body side and in contact with the upper end of the coil spring winding;
A lower seat disposed on the wheel side and in contact with the lower end of the coil spring winding;
When a reference load is applied to the coil spring, at least one end winding portion of the coil spring winding has a first wire diameter portion and a first wire diameter portion having a smaller wire diameter than the first wire diameter portion. A suspension device having two wire diameter portions. The suspension device is a strut suspension device;
The shock absorber is further disposed inside the coil spring, the upper end is connected to the vehicle body side member and the lower end is connected to the wheel side member,
The upper seat is fixed to a vehicle body side member,
The lower seat is fixed to a shock absorber,
The first wire diameter portion and the second wire diameter portion are arranged so that the lateral force generated by the coil spring is in a direction to cancel the bending moment acting on the shock absorber by the external force acting on the wheel from the road surface. The suspension device according to claim 1.   The suspension device according to claim 1 or 2, wherein the coil spring is a cylindrical coil spring. In the suspension device for connecting the vehicle body side member and the wheel side member of the vehicle, a suspension device coil spring disposed between a pair of seats respectively disposed on the vehicle body side and the wheel side,
A coil spring for a suspension device, wherein at least one of the upper end portion and the lower end portion of the coil spring winding has a first wire diameter portion and a second wire diameter portion having a smaller diameter than the first wire diameter portion. .

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