Suspension device

Abstract

To provide a suspension device for vehicle in which vibration absorption performance during travelling is improved.SOLUTION: A suspension device comprises a plurality of leaf springs 10, 20, 30 which are arranged in series in a cross direction of a vehicle. Leaf springs arranged in series respectively support separate axle, and connection members 40, 50 movably attached to a chassis are arranged between two adjacent front side and rear side leaf springs that are adjacent to each other. A leaf rear end part 12, 22, 32 at a rear end of the adjacent front side leaf springs and a leaf front end part 11, 21, 31 at a front end of the adjacent rear side leaf springs are connected to the connection member. A part of a load received by any one of two adjacent leaf springs can be transmitted to the other adjacent leaf spring via the connection member.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a suspension system for use in a vehicle, and more particularly to a suspension system using leaf springs. [Background technology]

[0002] Leaf springs are widely used as vehicle suspensions (see, for example, FIG. 1 of Patent Document 1). The leaf spring 1 has a rear end connected to a shackle 5 by a link mechanism (connected by a swivel pair), and the shackle 5 applies a forward biasing force to the rear end of the leaf spring 1. When the leaf spring receives an upward force, for example when the wheel hits a bump in the road surface, the elastic force of the leaf spring itself and the biasing force of the shackle act as a reaction force to perform the suspension function.

[0003] Furthermore, leaf springs are widely used not only in vehicles equipped with a power source, such as passenger cars, trucks, and even towing vehicles (tractors), but also in trailers (towed vehicles) (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-76481 A [Patent Document 1] JP 2019-6235 A Summary of the Invention [Problem to be solved by the invention]

[0005] Leaf springs are widely used and have the advantage of being simple in structure, but there are cases where consideration is needed to improve their vibration absorption performance. The present invention has been made in view of the above problems, and an object of the present invention is to provide a suspension device using leaf springs with improved vibration absorbing performance during driving. [Means for solving the problem]

[0006] The present invention is a suspension device for a vehicle that is arranged between a chassis and a number of axles equipped on the chassis, the suspension device comprising a number of leaf springs arranged in series in the fore-and-aft direction of the vehicle, each leaf spring supporting a different axle, and a connecting member that is rotatably attached to the chassis is arranged between two adjacent leaf springs on the front and rear sides that are adjacent to each other, and the connecting member connects the leaf rear end of the rear end of the front adjacent leaf spring and the leaf front end of the front end of the rear adjacent leaf spring, so that a portion of the load received by either of the two adjacent leaf springs can be transmitted to the other adjacent leaf spring via the connecting member.

[0007] At least one of the leaf rear end connecting structure between the leaf rear end and the connecting member and the leaf front end connecting structure between the connecting member and the leaf front end is a slide connection.

[0008] The leaf front end connecting structure is a rotary connection in which the leaf front end of the rear adjacent leaf spring is rotatably supported on the rear connecting portion of the connecting member, and the leaf rear end connecting structure is a slide connection in which the leaf rear end of the front adjacent leaf spring and the front connecting portion of the connecting member are slidably connected to each other, and a slider, which is the other, is slidably connected along a guide surface, which is one of the leaf rear ends and the front connecting portion, and the slider is slidable in a slide section between one abutment position where the slider abuts on an abutment portion on one end of the guide surface, and the other abutment position where the slider abuts on an abutment portion on the other end of the guide surface, and when the slider is positioned in the slide section, when the leaf rear end of the front adjacent leaf spring moves rearward and / or upward or moves forward and / or downward, the slider and the guide surface can slide relative to each other.

[0009] When the slider is positioned at one of the end positions and the rear leaf end of the front adjacent leaf spring moves rearward and / or upward, the connecting member rotates and the front leaf end of the rear adjacent leaf spring connected to the connecting member moves downward.

[0010] The leaf rear end has the guide surface, and the front connecting portion has a slider.

[0011] In addition, the number of the leaf springs arranged in series and each supporting a separate axle is three or more, the front end of the leaf of an intermediate leaf spring arranged between the foremost leaf spring and the rearmost leaf spring is rotatably supported by the rear connecting portion of the front connecting member arranged in front of the intermediate leaf spring, and a guide surface of the leaf rear end of the intermediate leaf spring is slidably connected to a slider of the front connecting portion of the rear connecting member arranged rearward of the intermediate leaf spring, so that a portion of the load received by the intermediate leaf spring can be transmitted to the front adjacent leaf spring adjacent at the front side via the front connecting member, and can also be transmitted to the rear adjacent leaf spring adjacent at the rear side via the rear connecting member.

[0012] In addition, when the slider is positioned at one of the end positions, the change in the deflection of the intermediate leaf spring causes the rear end of the leaf of the intermediate leaf spring to move rearward and / or upward, causing the rear connecting member to rotate, resulting in a downward movement of the front end of the leaf of the rear adjacent leaf spring connected to the rear connecting member, and / or the front end of the leaf of the intermediate leaf spring to move forward and / or upward, causing the front connecting member to rotate.

[0013] When the vehicle is stopped on the road, the slider is located within the slide section and is located above the pivot axis of the connecting member that is rotatably connected to the chassis, and the front end of the leaf of the rear adjacent leaf spring is located above the pivot axis.

[0014] Moreover, each of the axles supports a driven wheel. The vehicle is also a towed vehicle that is not equipped with a braking device for braking the driven wheels.

[0015] The towed vehicle is a trailer house vehicle, the layout of which includes a heavy weight area with a relatively heavy weight per unit area and a light weight area with a relatively light weight, and the heavy weight area is located in the area above the second leaf spring located in the center of the three leaf springs arranged in series. Effect of the Invention

[0016] According to the present invention, it is possible to provide a suspension device that exhibits improved performance in terms of vibration absorbing performance during driving. [Brief description of the drawings]

[0017] [Figure 1] 1 is a side view showing a vehicle in which a suspension device according to the present invention is used; [Diagram 2] 1 is a side view showing a suspension device according to the present invention; [Diagram 3] 3 is an enlarged view showing a main portion of the suspension device shown in FIG. 2, where (A) is an enlarged side view showing the first leaf spring, (B) is an enlarged side view showing the second leaf spring, and (C) is an enlarged side view showing the third leaf spring. [Figure 4] 3A and 3B are enlarged views showing main parts of the suspension device shown in FIG. 2, in which (A) is an enlarged side view showing a state in which the first slide shaft portion of the first connecting member is positioned in the slide section, (B) is an enlarged side view showing a state in which the first slide shaft portion is positioned in the front end position, and (C) is an enlarged side view showing a state in which the first slide shaft portion is positioned in the rear end position. [Diagram 5] FIG. 3 is a side view showing a leaf spring used in the suspension system shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Next, the suspension device according to the present invention (see FIG. 2) will be described. Here, as shown in FIG. 1, an embodiment will be described in which the present invention is used in a towed vehicle (hereinafter, sometimes simply referred to as a vehicle) TH towed by a towing vehicle V such as a trailer. When the vehicle TH is viewed in a plan view, the suspension devices are arranged in a position close to the wheels on both the left and right sides, in a direction parallel or nearly parallel to the center line of the vehicle extending in the fore-aft direction X. However, here, we will explain one of the suspension devices 1 arranged close to the wheels on one side, and will not explain the other one. Furthermore, illustrations and descriptions of well-known structures relating to suspensions using leaf springs may be omitted.

[0019] As shown in FIG. 2, the suspension system 1 includes three leaf springs (three units) 10, 20, 30 arranged in series in the front-rear direction X of the vehicle TH. The leaf springs 10, 20, and 30 used in this embodiment are leaf springs configured by stacking a plurality of arch-shaped leaf springs that are curved convexly downward. The suspension system 1 also includes two connecting members 40, 50 disposed between the leaf springs 10, 20, 30. A chassis 60 of the vehicle TH on which the suspension system 1 is installed is provided with support members 61, 62, 63, and 64 used to fix the suspension system 1 in place. In the following description, when focusing on two adjacent leaf springs, one in front and one in back, that are adjacent to each other via a connecting member among the three (plural) leaf springs 10, 20, 30 arranged in series, the two leaf springs, one in front and one in back, may be referred to as a set of adjacent leaf springs (or simply, adjacent leaf springs). The leaf spring disposed on the front side of the adjacent leaf springs may be referred to as the front adjacent leaf spring, and the leaf spring disposed on the rear side of the adjacent leaf springs may be referred to as the rear adjacent leaf spring. Furthermore, of the three (three or more) leaf springs 10, 20, 30 arranged in series, the first leaf spring 10 arranged at the forefront may be referred to as the foremost leaf spring, the rearmost third leaf spring 30 may be referred to as the rearmost leaf spring, and the leaf spring (second leaf spring 20) arranged between the foremost leaf spring and the rearmost leaf spring may be referred to as the intermediate leaf spring. The intermediate leaf spring has both its front and rear ends connected to connecting members.

[0020] Of the support members, the front support member 61, which is located most forward, is a member that rotatably supports (pivotally supports) the front end portion (first eye) 11 of the first leaf spring 10, which is located most forward. The first intermediate support member 62 is a member that rotatably supports the first connecting member 40. The second intermediate support member 63 is a member that rotatably supports the second connecting member 50. The rear support member 64, which is located most rearward, is a member that supports the rear end portion (third slide portion 32) of the third leaf spring 30, which is located most rearward.

[0021] The first leaf spring 10 is rotatably connected to a front support member 61 of the vehicle TH at its front end, the first eye 11 (leaf front end), and is slidably connected to a second slide shaft portion 42 (slider) of the first connecting member 40 (described later), at its rear end, the first slide portion 12 (leaf rear end) (leaf rear end connecting structure, slide connection). Such a connection structure between the first slide portion (leaf rear end portion) 12 and the first connecting member 40 may be referred to as a leaf rear end connecting structure. The connection structure between the first slide portion 12 and the first connecting member 40 is a slide connecting structure. The rotation axis 11a of the first eye 11 is an axis extending in a horizontal lateral direction (a direction perpendicular to the paper surface in FIG. 2) perpendicular to the vehicle front-rear direction X.

[0022] As shown in FIG. 5, the first slide portion 12 of the first leaf spring 10 is formed by bending the rear end portion of the longest spring (hereinafter sometimes referred to as the parent spring) 10a, which is located at the top row among the multiple leaf springs that make up the first leaf spring 10, and is an integral structure with the parent spring 10a. The first sliding portion 12 is a portion that is disposed at the rear end of the main spring 10a and has what can be called an oval shape. More specifically, the first slide portion 12 includes a plate-shaped lower guide portion 121 extending to connect to the rear end side of the main body portion of the arch-shaped parent spring 10a which is curved convexly downward, a plate-shaped upper guide portion 122 arranged opposite and above the lower guide portion, a rear end semicircular arc portion 123 which is connected to the rear end of the lower guide portion 121 and the rear end of the upper guide portion 122 and is curved in a convex shape toward the rear, and a front end semicircular arc portion 124 which is connected to the front end of the upper guide portion 122, curves downward from the front end of the upper guide portion 122 and is curved in a convex shape toward the front. In other words, the first slide portion 12 has a so-called oval-shaped first hollow portion (hereinafter sometimes referred to as the first slide groove) 13 surrounded by a lower guide portion 121, an upper guide portion 122, a rear end semicircular arc portion 123 and a front end semicircular arc portion 124. The first slide groove 13 is a long groove (long hole) extending in the extension direction Xs along the parent spring 10a, which is curved convexly downward, and penetrates in the horizontal direction (perpendicular to the paper surface in Figure 5), and has a lower guide surface (upper surface of the lower guide portion 121) 121a and an upper guide surface (upper surface of the upper guide portion 122) 122a extending in the extension direction Xs of the parent spring 10a. In other words, the first slide shaft portion (the other sliding pair) 42 described below, which is slidably connected to the first slide portion 12, can also be said to be slidably connected to the first slide groove 13 (one of the sliding pairs). Incidentally, since the extending direction Xs of the first slide portion 12 (first slide groove, parent spring 10a) is substantially the same direction as the front-rear direction X, the direction of the first slide portion 12 may be referred to as the front-rear direction X.

[0023] In addition, since the configurations of the second leaf spring 20 and the third leaf spring 30 are similar to that of the first leaf spring 10, a description thereof will be omitted here. The common configurations will be given the same names, and as necessary, the terminology will be such that "second" or "third" is added instead of "first" in front of the name.

[0024] The first connecting member 40 (see Figure 3 (A) etc.) comprises a first pivot shaft portion 41 rotatably connected to the first intermediate support member 62, a rod-shaped first slide shaft portion 42 (front connecting portion) connected to the first slide portion 12 of the first leaf spring 10, and a first interlocking shaft portion 43 (rear connecting portion) on which the front end eye (second eye) 21 of the second leaf spring 20 is rotatably supported. The first rotating shaft portion 41 is formed in the center of the first connecting member 40, the first sliding shaft portion 42 is positioned forward of the first rotating shaft portion 41, and the first interlocking shaft portion 43 is positioned rearward of the first rotating shaft portion 41. The rotation axis direction of the first rotation shaft portion 41 and the first interlocking shaft portion 43, and the extending direction of the rod-shaped first slide shaft portion 42 are all the above-mentioned horizontal direction (the direction perpendicular to the paper surface in FIG. 3).

[0025] In addition, the configuration of the second connecting member 50, which is supported so as to be freely rotatable by the second intermediate support member 63 (see Figure 2), is similar to that of the first connecting member 40, so a description thereof will be omitted here. The common configuration will be given the same name, and, where necessary, the term "second" will be used instead of "first" before the name.

[0026] In a structure using such members 10, 20, 30, 40, 50, a portion of the force received by the first leaf spring 10 can be transmitted to the second leaf spring 20 via rotation of the first connecting member 40 at the first pivot shaft portion 41, and conversely, a portion of the force received by the second leaf spring 20 can be transmitted to the first leaf spring 10 via rotation of the first connecting member 40 at the first pivot shaft portion 41. In other words, in the suspension device 1, when the first leaf spring 10 is subjected to a load such as an upward force FA1 (see Figure 2) described below, a portion of that force can be transmitted to the second leaf spring 20 via the first connecting member 40, so that the upward force FA1 can be received in cooperation with the first leaf spring 10 and the second leaf spring 20.

[0027] Next, the configuration of the first connecting member 40 will be further described mainly with reference to FIG. The first connecting member 40 shown in FIG. 4(A) is in a state in which the first slide shaft portion 42 and the first interlocking shaft portion 43 are positioned at the same height. The first connecting member 40 has a front arm portion 40b extending diagonally upward and forward from the front end of the central portion 40a in which the first rotating shaft portion 41 is formed, and a first sliding shaft portion 42 is arranged at the front end of the front arm portion 40b. The first connecting member 40 also includes a rear arm portion 40c that extends obliquely upward and rearward from the rear end of the central portion 40a, and a first interlocking shaft portion 43 is disposed at the rear end of the rear arm portion 40c. In other words, when the first slide shaft portion 42 and the first interlocking shaft portion 43 are positioned at the same height, the first slide shaft portion 42 and the first interlocking shaft portion 43 are positioned above the first rotating shaft portion 41. For example, when the vehicle TH is parked on the road (and capable of being driven), the first slide shaft portion (slider) 42 is located within the slide section Pm and is located above the first pivot shaft 41 of the first connecting member 40 which is rotatably connected to the chassis 60, and the second eye (front end of the leaf) 21 of the second leaf spring (rear adjacent leaf spring) 20 is located above the first pivot shaft 41. In this embodiment, the distance D1 between the first rotation shaft 41 and the first slide shaft 42 and the distance D2 between the first rotation shaft 41 and the first interlocking shaft 43 are equal. Furthermore, comparing the first leaf spring 10 and the first connecting member 40, the above-mentioned separation distances D1, D2 in the first connecting member 40 are shorter than the distance S between the front and rear support positions of the first leaf spring 10 (see FIG. 5). The support position distance S is the distance between the first eye 11 and the first slide shaft portion 42, and varies with the movement of the first slide shaft portion 42 caused by the rotation of the first connecting member 40. When the first slide shaft portion 42 is positioned in a slide section Pm described below (for example, the state shown in FIG. 4(A)), if the deflection state of the first leaf spring 10 undergoes a load such as an upward force FA1 (see FIG. 2) described below and the distance S between the support positions changes, causing the position of the rear end portion (for example, the first slide portion 12) of the first leaf spring 10 to change (move in the front-to-back and / or up-down directions), most of the change is absorbed by the slide between the first slide shaft portion 42 and the first slide shaft portion 42, and a part of the force caused by the change is transmitted to the second slide shaft portion 42 (first connecting member 40) side via frictional force. On the other hand, for example, when the first slide shaft portion 42 is positioned at the front end position (one of the end positions) P1 of the first slide portion 12 described below (see Figure 4 (B)), if the deflection state of the first leaf spring 10 receives an upward force FA and the position of the rear end portion (e.g., the first slide portion 12) of the first leaf spring 10 changes (moves rearward and / or upward), the change is transmitted in its entirety to the first slide shaft portion 42 and absorbed by the rotational movement RL1 of the first connecting member 40 (first slide shaft portion 42). Furthermore, when the first slide shaft portion 42 is positioned at the rear end position (the other end position) P2 of the first slide portion 12 described below (see Figure 4 (C)), if the deflection state of the first leaf spring 10 receives the downward force FB and the position of the rear end portion (e.g., the first slide portion 12) of the first leaf spring 10 changes (moves forward and / or downward), the change is transmitted in its entirety to the first slide shaft portion 42 and absorbed by the rotational movement RL2 of the first connecting member 40 (first slide shaft portion 42). In this way, the suspension device 1 of this embodiment is configured so that the mechanism for absorbing fluctuations in the deflection of the first leaf spring 10 (and the forces resulting from the fluctuations) changes depending on whether the first slide shaft portion (slider) 42 is positioned in the slide section Pm or not. In this embodiment, when the first slide portion (first leaf rear end portion) 12 moves rearward and / or upward relative to the first slide shaft portion (front connecting portion, slider) 42, the first slide shaft portion (slider) 42 finally moves to one end position (front end position) P1 where the first slide portion (first leaf rear end portion (guide surface) 12 abuts against an end portion on one end side of the first slide portion (first leaf rear end portion (guide surface) 12), and when the first slide portion (first leaf rear end portion) 12 moves forward and / or downward relative to the first slide shaft portion (front connecting portion, slider) 42, the first slide shaft portion (slider) 42 finally moves to the other end position (rear end position) P2 where the first slide portion (first leaf rear end portion (guide surface) 12 abuts against an end portion on the other end side of the first slide portion (first leaf rear end portion (guide surface) 12), and the first slide shaft portion (front connecting portion, slider) 42 is slidable in a slidable slide section between one end position P1 and the other end position P2. In addition, with regard to the fluctuation in the deflection of the leaf springs 10, 20, 30, when the leaf spring is subjected to, for example, an upward force FA (FA1, FA2, FA3) and the radius of curvature increases, the deformation may be referred to as a fluctuation (deformation) in which the deflection increases (weakes), and when the leaf spring is subjected to, for example, a downward force FB (FB1, FB2, FB3) and the radius of curvature decreases, the deformation may be referred to as a fluctuation (deformation) in which the deflection increases.

[0028] The first slide shaft portion 42 is slidable relative to the first slide portion 12 along the extension direction (longitudinal direction) Xs of the first slide portion 12. In other words, the first slide shaft portion 42 is movable between a front end position P1 (see FIG. 4(B)) where it abuts against the front end of the first slide portion 12 and a rear end position P2 (see FIG. 4(C)) where it abuts against the rear end of the first slide portion 12. In addition, regarding the slide portion 12 (22, 32), a position (range) between the front end position P1 and the rear end position P2 in which the slide shaft portion 42 (52) can slide is sometimes referred to as a slide section Pm (see FIG. 5), and a position within the slide section is sometimes referred to as a slide position Pm. In addition, among the slide positions Pm, a central position equidistant from the slide front end position P1 and the slide rear end position P2 is sometimes referred to as a slide central position Ps. It should be noted that detailed description of the configuration of the second connecting member 50 is omitted for the same reasons as mentioned above.

[0029] Next, the operation of the suspension system 1 will be described.

[0030] Here, as shown in FIG. 1, a case will be described in which the tire T of the vehicle TH is subjected to vertical forces (loads) such as an upward force FA and a downward force FB, based on a state in which the tire T of the vehicle TH is in contact with the road surface XR in a drivable state. The upward forces FA (FA1, FA2, FA3) referred to here are, for example, upward forces (forces pushing upward) that the tire T of a moving vehicle TH receives when the tire T passes over a convex portion XRa (see FIG. 1) of the road surface XR. The downward forces FB (FB1, FB2, FB3) referred to here are forces in the opposite direction to the upward forces, for example, a downward force that the tire T of a moving vehicle TH receives when it passes over a depression in the road surface XR (a force in the direction of gravity that the tire T receives after the reaction force of gravity received from the road surface XR is released).

[0031] In the following explanation, we may use a boundary surface B1 (see Figure 3) that passes through the first eye 11 at the front end of the first leaf spring 10 and the first pivot shaft portion 41 of the first connecting member 40 connected to the rear end side of the first leaf spring 10. Unless otherwise specified, the following description will be directed to a state in which the position of the slide shaft portion (center) 42 (52) is located in the area above the boundary surfaces (boundary lines) B1, B2, both when the vehicle TH is stopped and when it is moving. In addition, the following explanation relates to the case where the angle α1 (the intersection angle located below the direction of gravity) between the line segment L1 connecting the first eye 11 and the first slide shaft portion 42 and the line segment L2 connecting the first rotating shaft portion 41 and the first slide shaft portion 42 is greater than 90 degrees and less than 180 degrees (greater than or equal to 90 degrees and less than or equal to 180 degrees), as shown in Figure 3(A). In other words, the suspension system 1 of this embodiment is configured to operate within such a range.

[0032] [Operation description 1] The following description will be given starting from a state in which the first slide shaft portion 42 of the first connecting member 40 is located in the slide section Pm (see FIG. 4(A)) of the first slide portion 12 as shown in FIG.

[0033] In this state, when the first tire T1 (first axle A1) receives an upward force FA1, the force is transmitted to the first leaf spring 10. The upward force FA1 is a force that acts to straighten (increase the radius of curvature) the downwardly convex curved (warped) first leaf spring 10; in other words, it is a force that causes a deformation (fluctuation) in which the deflection of the first leaf spring 10 is straightened. At this time, since the first eye 11 at the front end is axially supported by the front end support member 61, when the warp of the first leaf spring 10 receiving the upward force FA1 straightens, a force Fp (not shown) is generated which moves the first slide portion 12 of the first leaf spring 10 rearward in the longitudinal direction Xs (see Figure 4(A)) of the first leaf spring 10 (parent spring 10a). In addition, when the first leaf spring 10 receives an upward force FA1, a force Fq (not shown) is generated in the first leaf spring 10, which rotates the first slide portion 12 of the first leaf spring 10 upward (counterclockwise rotation in Figure 3 (A)) RS1 with the first front end eye 11 as the rotation axis. In the following description, the resultant force of these forces Fp, Fq generated when the first leaf spring 10 receives the upward force FA1 will be referred to as a rear transmission component force FR (FR1, FR2, FR3) (see FIG. 3). The direction and length of the arrow of the rear transmission component force FR shown in FIG. 3 and the like are shown for the sake of convenience so as to make it easier to understand, and are not necessarily accurate.

[0034] In the state shown in Figure 2, the first slide shaft portion 42 is located within a sliding section Pm in which it can slide relative to the first slide portion 12, and the rotation direction K1 (see Figure 4 (A)) of the first slide shaft portion 42 around the first rotation axis 41 is a direction that is close to the sliding direction Xs of the first slide shaft portion 42. The rearward transmission component force FR1 generated when the upward force FA1 is received includes a component force in the rotation direction K1 (clockwise force of the first slide shaft portion 42); however, when the rotation direction K1 and the sliding direction Xs of the first slide shaft portion 42 are similar and the first slide shaft portion 42 is slidable, most of the force component in the rotation direction K1 of the rearward transmission component force FR1 acts as a force that slides the first slide portion 12 rearward. That is, of the force of the rear transmission component force FR1 in the rotation direction K1, the force transmitted from the first leaf spring 10 side to the first connecting member 40 side is a part of the force transmitted via the frictional force generated between the first sliding portion 12 in a slidable state and the first sliding shaft portion 42. The force transmitted in this manner is a force that rotates the first connecting member 40 backward (clockwise RL1).

[0035] As described above, in the suspension device 1, the upward force FA1 received by the first leaf spring 10 can be received by the cooperation of the first leaf spring 10 and the second leaf spring 20. However, when the first slide shaft portion 42 is located within the slide section Pm of the first slide portion 12 (see Figures 2 and 4(A)), the proportion of the upward force FA1 received by the first leaf spring 10 that is transmitted to the second leaf spring 20 via the first connecting member 40 is relatively small, and it can be said that the transmitted force is only a portion of the force (relatively small).

[0036] When the first leaf spring 10 receives an upward force FA1 and a rearward transmission component force FR1 is generated, a force FF1 (see FIG. 3(A). Hereinafter, this may be referred to as a forward transmission component force FF) is generated in a direction that moves the first eye 11 forward. However, since the first eye 11 is supported by a front end support member 61 fixed to the vehicle body TH, the first eye 11 does not move in the fore-and-aft direction X of the vehicle body even when the forward transmission component force FF1 is generated.

[0037] As shown in FIG. 2, when the first slide shaft portion 42 of the first connecting member 40 is positioned in the slide section Pm of the first slide portion 12 and the first wheel T1 receives a downward force FB1, an action or movement occurs in the opposite direction to when the first wheel T1 receives an upward force FA1. The operation and action when a downward force FB1 is applied is basically the opposite of that when an upward force is applied, and the explanation will be given by substituting the opposite terms, so the explanation will be omitted here. Similarly, in the "Operation Explanations 2 to 6" described later, the explanation of the operation when a downward force is applied will be omitted.

[0038] [Operation description 2] When the first leaf spring 10 receives the upward force FA1, a deformation (fluctuation) occurs in which the deflection straightens out, and the first sliding portion 12 moves rearward, the first sliding shaft portion 42 in the first sliding portion 12 moves relatively toward the front end inside the first sliding portion 12. Then, when a large upward force is received, the first sliding shaft portion 42 eventually reaches a position P1 (hereinafter, simply referred to as the front end position) where it abuts against the front end semicircular arc portion 124 at the front end of the first sliding portion 12 (see FIG. 4(B)). When the first slide shaft portion 42 moves relatively rearward, it finally reaches the rear end position P2 (the position where it abuts against the rear end semicircular arc portion 123, the other abutting position) (see FIG. 4(C)).

[0039] Here, we will explain the case where the first tire T1 (first axle A1) receives an upward force FA1 when the first slide shaft portion 42 of the first connecting member 40 is positioned at the front end position (one of the end positions) P1 of the first slide portion 12 (see Figure 4 (B)). Note that the explanation of the contents common to "Operation Explanation 1" will be omitted.

[0040] In this state, when the first leaf spring 10 receives an upward force FA1, the first slide shaft portion 42 does not move (slide) relatively forward within the first slide portion 12, and therefore the rearward transmission force component FR1 of the upward force FA1 is transmitted directly from the first slide portion 12 to the first slide shaft portion 42 (first connecting member 40, second eye 21). When the first slide portion 12 moves rearward due to the rear transmission force FR, the first slide shaft portion 42 rotates rearward RL1 (see FIG. 4A) in the rotation direction K1 in conjunction with this (see FIG. 4A). At this time, the second eye 21 of the second leaf spring 20 rotates clockwise RL1 (downward in FIG. 4B) by the same angle as the rotation angle of the first slide shaft portion 42. Here, since the extension direction Xs of the first slide portion and the rotation direction K1 of the first slide shaft portion 42 are approximately the same direction, it can be said that the amount of rearward movement of the first slide portion 12 and the amount of rotation of the first slide shaft portion 42 (second eye 21) in the rotation direction K1 are approximately the same, and it can be said that the force (proportion of the force) transmitted to the second leaf spring 20 via the first connecting member 40 when the first leaf spring 10 receives an upward force FA1 is relatively larger compared to the case of "Operation Description 1". Similar to the case of “Operation Description 1,” the upward force FA1 received by the first leaf spring 10 can be received by the cooperation of the first leaf spring 10 and the second leaf spring 20, and the first eye 11 does not move in the fore-and-aft direction X of the vehicle body.

[0041] [Comparison between Operation Description 1 and Operation Description 2] As described above, for example, when the upward force FA1 (rear transmission component force FR1) is relatively small, and the first slide shaft portion 42 of the first connecting member 40 is positioned in the slide section Pm of the first slide portion 12 (see FIG. 4(A)), the proportion of force transmitted from the first leaf spring 10 side to the second leaf spring 20 side is relatively small, and the amount of rotation of the first slide shaft portion 42 (second eye 21) is relatively small. However, when the first slide shaft portion 42 receives a larger upward force FA1 (rear transmission component force FR1) and is positioned at the front end position P1 of the first slide portion 12, the proportion of the force transmitted from the first leaf spring 10 side to the second leaf spring 20 side of the rear transmission component force FR1 becomes relatively large.

[0042] In this way, the suspension device 1 is configured so that when the upward force FA1 received by the first leaf spring 10 becomes large, the force transmission changes from frictional transmission to direct transmission, and a larger proportion of the force can be transmitted from the first leaf spring 10 to the adjacent second leaf spring 20.

[0043] In the following description, as in the case of "Operation Description 1," a state in which the second slide shaft portion 42 is located within the slide section Pm of the first slide portion 12 and the rear transmission force component FR (or the front transmission force component FF) and the like are transmitted between the leaf springs 10, 20, 30 and the connecting members 40, 50 connected via slides (friction force, sliding pair) may be referred to as a "connected state with relatively low interlocking (interlocking state with relatively low cooperativity)." In this case, the proportion of the transmitted force in the rear transmission force component FR (or the front transmission force component FF) and the like is relatively small. Also, as in the case of "Operation Description 2," the state in which the second slide shaft portion 42 is located at the front end position P1 of the first slide portion 12 and the rear transmission component force FR (or the front transmission component force FF, etc.) is directly transmitted between the leaf spring 10 and the connecting member 40 that are connected to each other is sometimes referred to as a "relatively highly interlocking state (relatively highly cooperative state)." In this case, the proportion of the transmitted force in the rear transmission component force FR (or the front transmission component force FF, etc.) is relatively large. In other words, the direct transmission here means that the rear transmission component force FR (or the front transmission component force FF) is transmitted by a so-called link mechanism via a pivot connection (turning pair) rather than by a slide (friction force, sliding pair).

[0044] [Operation description 3] As shown in Figure 2, a case will be described in which the second tire T2 (second axle A2) receives an upward force FA2 when the first slide shaft portion 42 of the first connecting member 40 is positioned in the slide section Pm of the first slide portion 12 and the second slide shaft portion 52 of the second connecting member 50 is positioned in the slide section Pm of the second slide portion 22. Note that explanations of the contents common to "Operation Explanations 1 and 2" may be omitted.

[0045] When the second tire receives an upward force FA2 in this state, that force is transmitted to the second leaf spring 20. This causes the second leaf spring 20 to deform (stretch) so as to expand its deflection, generating a rearward transmission force component FR2 of the upward force FA2. Then, a portion of the force component of the rear transmission force FR2 in the rotational direction K1 is transmitted from the second leaf spring 20 to the second connecting member 50 via the friction force between the second slide portion 22 and the second slide shaft portion 52.

[0046] However, unlike the first eye 11, the second eye 21 at the front end of the second leaf spring 20 is connected in a axially supported state to the first interlocking shaft portion 43 of the first connecting member 40, and is capable of rotating around the first rotating shaft 41. Therefore, a rearward transmission force component FR2 is generated in the second leaf spring 20, and a forward transmission force component FF2 (see Figure 3B) is generated in a direction that moves the second eye 21 on the front end side forward, and this is transmitted to the first leaf spring 10 side by frictional force via the first connecting member 40. The above-mentioned connection structure between the second eye 21 at the front end of the second leaf spring 20 and the first interlocking shaft portion 43 of the first connecting member 40 may be referred to as a leaf front end connection structure. The second eye 21 and the first interlocking shaft portion 43 are a rotational connection structure (rotating connection structure).

[0047] In this way, in the suspension device 1 of this embodiment, when the second leaf spring 20 receives an upward force FA2, a portion of that force can be transmitted to both the first leaf spring 10 and the third leaf spring 30, and the upward force FA2 received by the second leaf spring 20 can be received by the cooperation of the first, second and third leaf springs 10, 20, 30.

[0048] The state of "Operation Description 3" is a state in which the first slide shaft portion 42 and the second slide shaft portion 52 are positioned in the slide section Pm of the first slide portion 12 and the second slide portion 22, and is a connected state with relatively low interlocking. Therefore, when a rear transmission component force FR2 and a front transmission component force FF2 are generated, the proportion of force transmitted from the second leaf spring 20 to the adjacent second connecting member 50 (third leaf spring 30) side and the first connecting member 40 (first leaf spring 10) side is relatively small.

[0049] [Operation description 4] Next, we will explain the case where the second tire T2 (second axle A2) receives an upward force FA2 when the second slide shaft portion 52 of the second connecting member 50 is positioned at the front end position P1 of the second slide portion 22 (see Figure 4 (B)). Note that the explanation of the contents common to "Operation Explanations 1 to 3" may be omitted.

[0050] In this state, when the second leaf spring 20 receives an upward force FA2, a fluctuation occurs in which the deflection of the second leaf spring 20 extends, but since the second slide shaft portion 52 cannot move forward within the second slide portion 22, the rearward transmission force component FR2 of the upward force FA2 is transmitted directly from the second slide shaft portion 22 to the second slide shaft portion 52 (second connecting member 50, third eye 31). When the second slide portion 22 moves rearward (and / or upward) due to the rear transmission component force FR2, the second slide shaft portion 52 (second connecting member, rear connecting member) rotates rearward RL1 in the rotation direction K1 in conjunction with this. At this time, the third eye 31 of the third leaf spring 30 rotates clockwise RL1 (downward in FIG. 4B) by the same angle as the rotation angle of the second slide shaft portion 52. In this case, it can be said that the amount of rearward movement of the second slide portion 22 and the amount of rotation of the second slide shaft portion 52 (third eye 31) in the rotation direction K1 are almost the same, and the force (proportion) transmitted to the third leaf spring 30 via the second connecting member 20 when subjected to an upward force FA2 is relatively larger compared to the case of "Operation Description 3".

[0051] In addition, when the second leaf spring 20 receives an upward force FA2 and a rearward transmission force component FR2 is generated, a forward transmission force component FF2 is generated which moves the second eye 21 on the front end side forward and is transmitted to the first connecting member 40 (the first leaf spring 10 side). When the second eye (leaf front end) 21 rotates forward (and / or upward) due to the forward transmission force component FF2, the first connecting member (front connecting member) 40 rotates in conjunction with this, and the force is transmitted to the first leaf spring 10 side.

[0052] The state of "Operation Description 4" is a state in which the second slide shaft portion 52 is positioned at the front end position P1 of the second slide portion 22, and is a connected state with relatively high interlocking. Therefore, when the rear transmission force component FR2 and the front transmission force component FF2 are generated, the proportion of force transmitted from the second leaf spring 20 to the adjacent second connecting member 50 side and the first connecting member 40 side is relatively large. In addition, when a forward transmission force component FF2 is generated, the proportion of force transmitted from the second leaf spring 20 to the first leaf spring 10 via the adjacent first connecting member 40 is determined by whether the connection state between the first slide shaft portion 42 and the first slide portion 12 is a relatively highly interlocking connection state or a relatively low interlocking state.

[0053] Also, the upward force FA2 can be received by the cooperation of the first to third leaf springs 10, 20, 30, similarly to the case of "Operation Description 3."

[0054] [Comparison between Operation Description 3 and Operation Description 4] Similar to the relationship between Operation Description 1 and Operation Description 2, the suspension device 1 is configured such that when the upward force FA2 received by the second leaf spring 20 becomes large, the force transmission changes from frictional transmission to direct transmission, so that a larger proportion of the force can be transmitted from the second leaf spring 20 to the adjacent third leaf spring 30 and the first connecting member 40.

[0055] [Operation description 5] As shown in Figure 2, a case will be described in which the third tire T3 (third axle A3) receives an upward force FA3 when the second slide shaft portion 52 of the second connecting member 50 is positioned in the slide section Pm of the second slide portion 22 and the third slide shaft portion 65 of the fourth support member 64 is positioned in the slide section Pm of the third slide portion 32. Note that the contents common to "Operation Descriptions 1 to 4" may be omitted.

[0056] In this state, when the third tire T3 receives an upward force FA3, the force is transmitted to the third leaf spring 30, causing deformation (variation) in which the third leaf spring 30 expands, generating a rear transmission force component FR3 (see FIG. 3(C)). Of the force component of the rear transmission force FR3 in the rotational direction K1, a portion of the force is transmitted from the second leaf spring 30 to the third slide shaft portion 65 (rear support member 64) via the friction force between the third slide portion 32 and the third slide shaft portion 65. Since the third slide shaft portion 65 is fixed to the rear support member 64, when a rear transmission force component FR3 is generated, the third slide portion 32 can slide relative to the fixed third slide shaft portion, but the third slide shaft 65 does not move even when subjected to a force from the third slide portion 32.

[0057] The third eye 31 at the front end of the third leaf spring 30 is supported by the second interlocking shaft portion 53 of the second connecting member 50 and is rotatable, similar to the second eye 11. Therefore, when a rearward transmission component force FR3 is generated in the third leaf spring 30, a forward transmission component force FF3 that moves the third eye 31 at the front end side forward is generated and is transmitted to the second leaf spring 20 side via the second connecting member 50 by frictional force.

[0058] In this way, the suspension system 1 is configured so that the upward force FA3 received by the third leaf spring 30 can be received by the second and third leaf springs 20, 30 in cooperation with each other.

[0059] The state of "Operation Description 5" is a state in which the second slide shaft portion 52 and the third slide shaft portion 65 are positioned in the slide section Pm of the second slide portion 22 and the third slide portion 32, and is a connected state with relatively low interlocking, so that when the rear transmission force component FR and the front transmission force component FF are generated, the proportion of force transmitted from the third leaf spring 30 to the adjacent second connecting member (second leaf spring) is relatively small.

[0060] [Operation Description 6] A case will be described where the third tire T3 (third axle A1) receives an upward force FA3 while the third slide shaft portion 65 is located at the front end position P1 of the third slide portion 32. Note that the explanation of the contents common to "Operation Explanations 1 to 5" may be omitted.

[0061] When the third leaf spring 30 receives an upward force FA3 in this state, the deflection of the third leaf spring 30 stretches, causing a deformation (fluctuation), resulting in a rearward transmission force component FR3 and a forward transmission force component FF3. However, since the third slide shaft portion 65 is fixed to the rear support member 64, the third slide shaft portion 65 and the third slide portion 32 do not move rearward due to the rearward transmission force component FR. On the other hand, the forward transmission component force FF3 acts as a force that moves the third eye 31 on the front end side forward, and is transmitted to the second connecting member 50, and the force is transmitted to the first leaf spring 10 side.

[0062] The state of "Operation Description 6" is a state in which the third slide shaft portion 65 is positioned at the front end position P1 of the third slide portion 32, and is a connected state with relatively high interlocking, so that when a forward transmission component force FF3 is generated, the force transmitted from the third leaf spring 30 to the adjacent second connecting member 50 is relatively large. In addition, when a forward transmission force component FF3 is generated, the proportion of force transmitted from the third leaf spring 30 to the second leaf spring 20 via the adjacent second connecting member 50 is determined by whether the connection state between the second slide shaft portion 52 and the second slide portion 22 is a relatively highly interlocking connection state or a relatively low interlocking state.

[0063] Also, FA3 can be supported by the cooperation of the second and third leaf springs 20, 30, which is the same as in the case of "Operation Description 5."

[0064] [Comparison of Operation Description 5 and Operation Description 6] Similar to the relationship between Operation Description 3 and Operation Description 4, the suspension device 1 is configured such that when the upward force FA3 received by the third leaf spring 30 becomes large, the force transmission changes from frictional transmission to direct transmission, so that a larger proportion of the force can be transmitted from the third leaf spring 30 side to the adjacent second connecting member 50.

[0065] Next, the movement of the suspension system of this embodiment will be described while assuming a situation in which the vehicle is running.

[0066] The suspension system 1 of a vehicle TH undergoes various forces while in motion and exhibits complex behavior, but here we will explain the effects of the suspension system 1 by focusing on its behavior when it receives an upward force FA. Therefore, this does not necessarily coincide with the actual behavior.

[0067] Here, the operation of the suspension device 1 having the three leaf springs 10, 20, 30 arranged in series will be described starting from the state shown in FIG.

[0068] [Mitigation of vibration caused by upward force FA1 applied to first tire T1] In this state, when the traveling vehicle TH approaches, for example, a convex portion XRa (see FIG. 1) on the road surface XR or an uphill slope, the first tire T1 (first axle A1) first receives an upward force FA1 from the convex portion. As a result, the first leaf spring 10 receives an upward force FA1, and a rearward transmission component force FR1 of the upward force FA1 is generated.

[0069] Here, when the magnitude of the upward force FA1 is relatively small, the first slide shaft portion 42 connected to the first slide portion 12 is maintained in a state in which it is positioned in the slide section Pm within the first slide portion 12 (a state in which interlocking is relatively low). When the interlocking is low, as described above, the proportion of the force transmitted to the second leaf spring 20 side via the first connecting member 40 is small among the rear transmission component force FR1 of the upward force FA1 received by the first leaf spring 10. In other words, most of the upward force FA1 (rear transmission component force FR1) is received by the elastic deformation (deformation in which the warp is straightened) of the first leaf spring 10, and the generation of vibration is mitigated.

[0070] On the other hand, when the vehicle TH approaches a convex portion XRa (see FIG. 1) on the road surface XR while traveling and the upward force FA1 received by the first leaf spring 10 is relatively large, a larger rearward transmission force component FR1 is generated, which may result in the first slide shaft portion 42 being positioned at the front end position P1 (see FIG. 4(B)) of the first slide portion 12 (a state in which interlocking is relatively high). When the interlocking is high, not only is the rearward transmission force component FR1 large, but the proportion of the force transmitted to the second leaf spring 20 via the first connecting member 40 in the rearward transmission force component FR1 also increases.

[0071] In this way, in the suspension system, when the upward force FA1 received from the road surface becomes large and the linkage becomes high, a larger force is transmitted to the second leaf spring 20 side compared to when the upward force FA1 received from the road surface is small and the linkage is low. In other words, in the suspension system, when the first leaf spring 10 is subjected to a large upward force FA1, a large proportion of the force is transmitted to the adjacent second leaf spring 20, and the cooperation of both leaf springs 10, 20 makes it possible to more effectively and reliably mitigate the generation of large vibrations caused by the large upward force FA1.

[0072] [Mitigation of vibration caused by upward force FA2 applied to second tire T2] Thereafter, as the vehicle TH travels further, the first tire T1 passes the protruding portion XRa, and the second tire T2 approaches the protruding portion XRa. As a result, the second leaf spring 20 receives the upward force FA2, and a rearward transmission force component FR2 and a forward transmission force component FF2 of the upward force FA2 are generated.

[0073] When the magnitude of the upward force FA2 is relatively small, the second slide shaft portion 52 connected to the second slide portion 22 is maintained in a state in which it is located in the slide section Pm within the second slide portion 22 (a state in which the interlocking is relatively low). When the interlocking is low, as described above, the proportion of the rear transmission force component FR2 transmitted to the third leaf spring 30 via the second connecting member 50 is small, and the proportion of the front transmission force component FF2 transmitted to the first leaf spring 10 via the first connecting member 40 is small. In other words, most of the upward force FA2 (rear transmission force component FR2 and front transmission force component FF2) is received by the elastic deformation (deformation in which the warp is straightened) of the second leaf spring 20, and the generation of vibration is mitigated.

[0074] On the other hand, when the vehicle TH approaches a convex portion XRa (see FIG. 1) on the road surface XR while traveling and the upward force FA2 received by the second leaf spring 20 is relatively large, a larger rear transmission force component FR2 is generated, which may result in the second slide shaft portion 52 being positioned at the front end position P1 of the second slide portion 22 (a state in which the interlocking is relatively high). When the interlocking is high, not only is the rearward transmission force component FR2 large, but the proportion of the force transmitted to the third leaf spring 30 via the second connecting member 50 in the rearward transmission force component FR2 also increases. In addition, in the case of the second leaf spring 20, the proportion of the force transmitted to the first leaf spring 10 side via the first connecting member 40 also increases with respect to the forward transmission component force FF2 generated together with the rearward transmission component force FR2.

[0075] In this way, in the suspension system 1, when the upward force FA2 received from the road surface becomes large and the linkage becomes high, a larger force is transmitted to the third leaf spring 30 side and also to the first leaf spring 10 side, compared to when the upward force FA2 received from the road surface is small and the linkage is low. In other words, in the suspension device 1, when the second leaf spring 20 is subjected to a large upward force FA2, a large proportion of the force is transmitted to the adjacent first leaf spring 10 and third leaf spring 30 both at the front and rear, and the cooperation of the three leaf springs 10, 20, 30 makes it possible to more effectively and reliably mitigate the generation of large vibrations caused by the large upward force FA2.

[0076] [Mitigation of vibration caused by upward force FA3 applied to third tire T3] Thereafter, as the vehicle TH travels further, the second tire T2 passes the protruding portion XRa, and the third tire T3 approaches the protruding portion XRa. As a result, the third leaf spring 30 receives the upward force FA3, and a rearward transmission force component FR3 and a forward transmission force component FF3 of the upward force FA3 are generated.

[0077] When the magnitude of the upward force FA3 is relatively small, the third slide shaft portion 65 connected to the third slide portion 32 is maintained in a state in which it is located in the slide section Pm within the third slide portion 32 (a state in which the interlocking is relatively low). When the interlocking is low, as described above, the proportion of the force transmitted to the third slide shaft portion 65 (rear support member 64) of the rear transmission force component FR3 is small, and the proportion of the force transmitted to the second leaf spring 20 via the second connecting member 50 is small of the front transmission force component FF3. In other words, most of the upward force FA3 (rear transmission force component FR3 and front transmission force component FF3) is received by the elastic deformation (deformation in which the warp is straightened) of the third leaf spring 30, and the generation of vibration is mitigated.

[0078] On the other hand, when the vehicle TH approaches a convex portion XRa (see FIG. 1) on the road surface XR while traveling and the upward force FA3 received by the third leaf spring 30 is relatively large, a larger rear transmission force component FR3 is generated, which may result in the third slide shaft portion 65 being positioned at the front end position P1 of the third slide portion 32 (a state in which the interlocking is relatively high). When the interlocking is high, a larger rear transmission force component FR3 and a larger front transmission force component FF3 are generated; however, since the third slide shaft portion 65 is fixed to the rear support member 64, the proportion of the forward transmission force component FF3 that is transmitted to the second leaf spring 20 side via the second connecting member 50 becomes larger.

[0079] In this way, in the suspension system 1, when the upward force FA3 received from the road surface side becomes large and the interlocking becomes high, a larger force is transmitted to the second leaf spring 20 side compared to when the upward force FA2 received from the road surface side is small and the interlocking is low. In other words, in the suspension device 1, when the third leaf spring 30 is subjected to a large upward force FA3, a large proportion of the force is transmitted to the adjacent second leaf spring 20 at the front, and the cooperation of the second and third leaf springs 20, 30 makes it possible to more effectively and reliably mitigate the generation of large vibrations caused by the large upward force FA3.

[0080] As can be seen from the above explanation, when the suspension device 1 is subjected to a large upward force FA (downward force FB), the impact is not absorbed solely by the leaf spring that receives the force, but rather the impact is effectively absorbed by cooperation with adjacent leaf springs.

[0081] In particular, in the second leaf spring 20 having adjacent leaf springs on both the front and rear sides, when a large upward force FA2 (downward force FB2) is received, the force is effectively transmitted to the leaf springs on both the front and rear sides, and the impact can be more effectively mitigated in cooperation with the leaf springs on both the front and rear sides.

[0082] The suspension system 1 of the above-described embodiment is an example used in a towed vehicle, and the axles supported by each leaf spring of the suspension system 1 are fitted with driven wheels. Although the suspension system 1 is suitable for vehicles that do not have braking devices for the wheels (driven wheels), it can be used as a suspension for various vehicles.

[0083] Moreover, the suspension system of this embodiment is more suitable as a suspension system for a trailer house, for example, among other towed vehicles. The trailer house TH is a vehicle on which a living space is mounted (carried) and has, for example, a kitchen and other water facilities and compartments (living spaces) such as rooms. In addition, the weight per unit area of ​​the plots varies depending on their uses, and the layout (floor plan) of each plot is fixed in position. Incidentally, in the case of cargo vehicles that carry luggage, it is possible and common to load luggage while taking into consideration the overall balance of the vehicle, such as loading luggage so that the entire cargo vehicle has an even weight balance. However, as mentioned above, trailer houses have a fixed layout in which compartments with different weights per unit area are combined, and when trying to create a floor plan that prioritizes livability, it can easily become difficult to achieve a balanced state for the entire vehicle. That is, in the trailer house TH, there are inevitably sections THh having a heavy weight per unit area (hereinafter, heavy sections) and sections having a light weight per unit area.

[0084] As described above, the suspension device 1 of this embodiment has a configuration in which the three leaf springs 10, 20, and 30 are arranged in series. More specifically, two suspension devices 1 are disposed in series, parallel to each other and spaced apart from each other, on both the left and right sides of the trailer house vehicle TH. As described above, when the second leaf spring 20, which is located in the center in the fore-and-aft direction of the vehicle, receives a large upward force FA2 (see Figure 2), it is able to distribute and transmit that force to the leaf springs 10, 20 on both the front and rear sides. This configuration has superior shock absorption and vibration absorption capabilities compared to the first and third leaf springs 10, 30, which can only distribute force to adjacent leaf springs on either the front or rear side.

[0085] In this case, in the trailer house vehicle TH (see Figure 1), when comparing the central area THc above the second leaf spring 20 supporting the second axle A2 of the centrally located second tire T2, the front area THa above the first leaf spring 10 supporting the first axle A1 of the forward located first tire T1, and the rear area THe above the third leaf spring 30 supporting the third axle A3 of the rear located third tire T3, it can be said that the central area Hc has the best vibration damping performance when the weight section THh is located. Examples of the heavy section THh having a heavy weight per unit area include a water tank area and a water-related area including a water tank.

[0086] In this way, by using the suspension device 1 of this embodiment, even though a configuration is adopted in which leaf springs of the same performance and shape are arranged in series, an area suitable for arranging the weight section THh, i.e., an area (central area THc) with superior vibration damping performance, can be provided above the centrally arranged leaf spring. The layout configuration in which heavy sections THh such as the wet area are placed in the central area THc is a layout that further reduces vibration and shaking inside the trailer house vehicle when it is traveling, and contributes to reducing breakdowns and other problems caused by vibration of the trailer house vehicle's interior and installed items.

[0087] The invention of this application is not limited to the configurations described in the above embodiments, and includes modifications that do not deviate from the spirit of the invention.

[0088] For example, the suspension device 1 of this embodiment has three leaf springs arranged in series, but the number is not limited to three and may be any number (two or more than two). In a suspension system having three or more leaf springs arranged in series, the leaf springs arranged in the middle (central) position other than the leaf springs arranged in the front and rear rows are connected to connecting members on both the front and rear sides of the leaf springs. As can be seen from the explanation of the second leaf spring 20, such leaf springs are more likely to exhibit vibration damping performance than the front and rear leaf springs. In addition, when the number of leaf springs arranged in series is four or more, the upward force received by any one leaf spring can be transmitted to more leaf springs, which is advantageous in that it is possible to reduce the impact. Also, the central area THc suitable for arranging the weight section THh can be realized over a wide range. If the central area THc is wide, the freedom of arranging the gravity section THh increases, and the feasibility of a trailer house layout that combines livability and vibration control increases. On the other hand, when the number of leaf springs arranged in series is three, it has the characteristic that a configuration having intermediate leaf springs with excellent shock absorbing performance can be realized with the minimum number of leaf springs.

[0089] In addition, in the suspension device of this embodiment, the leaf springs are arranged so that the slide portions 12, 22, 32 (sliding pairs) are located on the rear end side of the leaf springs, but depending on the characteristics of the vehicle, a configuration in which the leaf springs are arranged so that the slide portions (sliding pairs) are located on the front end side of the leaf springs is also possible. [Explanation of symbols]

[0090] 1...suspension device, 10...first leaf spring, 10a...main spring, 11...first eye (first leaf front end, first front end eye), 11a...rotation axis of first eye, 12...First slide portion (rear end portion of first leaf, one sliding pair), 121...lower guide portion, 122...upper guide portion, 123...rear end semicircular arc portion (one end portion), 124...front end semicircular arc portion (the other end portion), 121a... guide surface (upper surface of the lower guide part), 122a... guide surface (upper surface of the upper guide part), 13...First hollow portion (first slide groove, one slide pair), 20…Second leaf spring (middle leaf spring), 21... second eye (second front end eye, second leaf front end), 21a... rotation axis of second eye, 22...Second slide portion (rear end portion of second leaf, one sliding pair), 23...Second hollow portion (second slide groove, one slide pair), 30…Third leaf spring, 31...third eye (third front end eye, third leaf front end), 31a...rotation axis of the third eye, 32...Third slide part (rear end of third leaf, one sliding pair), 33...Third hollow portion (third slide groove, one sliding pair), 40...First connecting member (front connecting member), 40a...center portion of first connecting member, 40b...front arm portion, 40c...rear arm portion, 41...first rotating shaft portion (first rotating shaft), 42...First slide shaft portion (front connecting portion, slider, other sliding pair), 43...First interlocking shaft portion (rear connecting portion), 50...second connecting member (rear connecting member), 50a...center portion of second connecting member, 50b...front arm portion, 50c...rear arm portion, 51...second rotating shaft portion (second rotating shaft), 52...Second slide shaft portion (front connecting portion, slider, other sliding pair), 53...Second interlocking shaft portion (rear connecting portion), 60... vehicle chassis (chassis), 61... front support member, 62... first intermediate support member, 63: second intermediate support member; 64: rear support member; 65...third slide shaft portion, A1,A2,A3...Axle, B1,B2...Boundary surface (boundary line), D1, D2: Inter-axis distance (separation distance) of connecting members, FA, FA1, FA2, FA3...upward force (load), FB, FB1, FB2, FB3...downward force (load), FF, FF1, FF2, FF3...Forward transmitted force, FR,FR1,FR2,FR3...Backward transmitted force, K1: rotation direction of the first connecting member; L1, L2: imaginary line segment; P1: (first) front end position of the slide portion (one end position), P2: rear end position of the (first) slide part (the other end position), Pm: slide section (slide position), Ps: first slide central position, RL1: rearward rotation direction of the first connecting member (second eye), RL2: forward rotation direction of the first connecting member (second eye), RS1: Leaf spring slide rotates upward (counterclockwise), RS2: Downward rotation of the leaf spring slide (clockwise), S: Distance between the front and rear support positions of the first leaf spring, T, T1, T2, T3...Tires, TH...Towed vehicle (vehicle, trailer house), THa: front area, THc: center area, THe: rear area, THh: weight section, V: trailer or other towing vehicle, X: Front-rear direction (vehicle front-rear direction), Xs: Extension direction (longitudinal direction) of the first slide portion (first slide groove, parent spring), XR: Road surface, XRa: Convex part of road surface, α1...Angle (the angle of the intersection located below the direction of gravity).

Claims

1. A suspension device for a vehicle disposed between a chassis and a plurality of axles provided on the chassis, A plurality of leaf springs are arranged in series in the front-rear direction of the vehicle, Each of the leaf springs arranged in series supports a different axle, A connecting member is disposed between two adjacent leaf springs on the front and rear sides that are adjacent to each other, the connecting member being pivotally attached to the chassis; a leaf rear end portion of a rear end of the front adjacent leaf spring and a leaf front end portion of a front end of the rear adjacent leaf spring are connected to the connecting member, A suspension device in which a portion of a load received by either one of the two adjacent leaf springs can be transmitted to the other adjacent leaf spring via the connecting member.

2. 2. The suspension device according to claim 1, wherein at least one of a leaf rear end connecting structure between the leaf rear end and the connecting member and a leaf front end connecting structure between the connecting member and the leaf front end is a slide connection.

3. the leaf front end connection structure is a rotational connection in which the leaf front end of the rear adjacent leaf spring is rotatably supported by the rear connection portion of the connection member, the leaf rear end connection structure is a slide connection in which the leaf rear end of the front adjacent leaf spring and the front connection part of the connection member are slidably connected to each other, and a slider which is one of the leaf rear end and the front connection part is slidably connected along a guide surface which is the other of the leaf rear end and the front connection part, the slider is slidable in a slide section between one abutment position where the slider abuts against an abutment portion on one end side of the guide surface and another abutment position where the slider abuts against an abutment portion on the other end side of the guide surface, 3. The suspension device according to claim 2, wherein when the slider is positioned in the sliding section and the leaf rear end of the front adjacent leaf spring moves rearward and / or upward or moves forward and / or downward, the slider and the guide surface can slide relative to each other.

4. 4. The suspension device according to claim 3, wherein when the leaf rear end of the front adjacent leaf spring moves rearward and / or upward with the slider positioned at one of the abutment positions, the connecting member rotates, and the leaf front end of the rear adjacent leaf spring connected to the connecting member moves downward.

5. 5. The suspension system according to claim 4, wherein said leaf rear end portion includes said guide surface, and said front connector portion includes a slider.

6. The number of said leaf springs arranged in series and each supporting a separate axle is three or more; a front end portion of an intermediate leaf spring disposed between the foremost leaf spring and the rearmost leaf spring is rotatably supported by the rear connecting portion of a front connecting member disposed in front of the intermediate leaf spring, a guide surface of a leaf rear end of the intermediate leaf spring is slidably connected to a slider of the front connecting portion of a rear connecting member arranged on the rear side of the intermediate leaf spring, 6. The suspension device according to claim 5, wherein a portion of the load received by the intermediate leaf spring is capable of being transmitted to the front adjacent leaf spring adjacent at the front side via the front connecting member, and is also capable of being transmitted to the rear adjacent leaf spring adjacent at the rear side via the rear connecting member.

7. When the slider is positioned at one of the end positions, the deflection of the intermediate leaf spring is increased by a fluctuation of an action in which the leaf rear end of the intermediate leaf spring moves rearward and / or upward, causing the rear connecting member to rotate, and causing the leaf front end of the rear adjacent leaf spring connected to the rear connecting member to move downward; an action in which the leaf front end portion of the intermediate leaf spring moves forward and / or upward to rotate the front connecting member; 7. The suspension of claim 6, which produces either or both of these movements.

8. When the vehicle is stopped on the road, The slider is located within the slide section and is located above a rotation axis of the connecting member that is rotatably connected to the chassis, 4. The suspension system according to claim 3, wherein a leaf front end of the rear adjacent leaf spring is located above the pivot shaft.

9. 9. A suspension system as claimed in any one of claims 1 to 8, wherein each of the axles supports a driven wheel.

10. 10. The suspension of claim 9, wherein the vehicle is for a towed vehicle that does not have a braking device for braking the driven wheels.

11. The towed vehicle is a trailer house vehicle, The trailer house vehicle has a layout including a heavy area having a relatively heavy weight per unit area and a light weight area having a relatively light weight per unit area, 11. The suspension system according to claim 10, wherein the weight area is disposed in an area above a second leaf spring disposed in the center among the three leaf springs disposed in series.

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