JP2021156295A - Shock absorber - Google Patents

Abstract

To provide a shock absorber equipped with a stroke sensor improving the durability of a rod extension part.SOLUTION: A shock absorber 20 includes an upper side outer tube 30, a lower side inner tube 40, a cylinder 50 in the inner tube 40, a cylindrical body 80 extending from a lower end 41 of the inner tube 40 into the cylinder 50, a piston rod 60 extending from an upper end 31 of the outer tube 30 into the cylinder 50, a piston 70 provided on the piston rod 60 and vertically moving forward/backward in the cylinder 50, a rod extension part 100 coupled to the piston 70 at an upper end 101 by a coupling mechanism 110 so as to rock with respect to a center line CL of the outer tube 30, and extending into the cylindrical body 80, and a coil 132 provided in the cylindrical body 80 so as to detect a slide position of the rod extension part 100 with respect to the cylindrical body 80.SELECTED DRAWING: Figure 2

Description

The present invention relates to a shock absorber suitable for use in a saddle-riding vehicle.

As a shock absorber adopted in a saddle-riding vehicle such as a motorcycle, there is a configuration that can be incorporated as one of the two shock absorbers constituting the front fork. In the front fork, for example, in order to grasp the traveling state of the saddle-riding vehicle, it may be required to detect the stroke amount of the shock absorber, which is the expansion / contraction distance of the front fork. Such a shock absorber is known, for example, in Patent Document 1.

The shock absorber known in Patent Document 1 includes a piston rod extending from the upper end of the outer tube located on the upper side to the inside of the inner tube located on the lower side, and an inner tube provided on the piston rod on the upper side. It is provided with a piston that divides the oil chamber and the lower oil chamber, and a rod extension portion (conductor member) that extends from the piston to the lower oil chamber. The upper end of this rod extension is fixed to the piston. A cylindrical coil portion is arranged in the lower oil chamber. The coil of the coil portion detects the slide position of the rod extension portion with respect to the inner tube. A stroke sensor is composed of a rod extension portion and a coil portion.

Japanese Unexamined Patent Publication No. 2016-194320

While driving a saddle-mounted vehicle, for example, due to the influence of an external force due to braking operation, the bending force (radial load, that is, the force in the direction intersecting the center line of the shock absorber) is applied to the shock absorber of the front fork. In, such a force may be simply referred to as a "bending force"). When a bending force acts on the shock absorber, the bending force may also act on the rod extension portion. Since the lower end of the rod extension is slidably supported by a bearing, movement in the radial direction is restricted. Therefore, bending stress can be concentrated on the upper end portion and the lower end portion of the rod extension portion. Since the rod extension portion is an elongated member that forms a part of the stroke sensor, its flexural rigidity is extremely small as compared with the piston rod. Therefore, it is preferable to increase the durability of the rod extension portion.

An object of the present invention is to provide a shock absorber provided with a stroke sensor having enhanced durability of a rod extension portion.

As a result of diligent studies, the present inventor has made the rod extension portion swingable with respect to the center line of the shock absorber when a bending force is applied to the rod extension portion, thereby making the rod extension portion durable. It has been found that it becomes possible to provide a shock absorber with improved sex. The present invention has been completed based on this finding.

According to the present invention, an outer tube having an upper end as a closed end and a lower end as an open end and an outer tube having an upper end as an open end and a lower end as a closed end are fitted so as to be able to advance and retreat a part of the inside of the outer tube. An inner tube, a cylinder extending from the lower end of the inner tube to the inside of the inner tube, a tubular cylinder extending from the lower end of the inner tube to the inside of the cylinder, and the outer. A piston rod extending from the upper end of the tube to the inside of the cylinder, a piston provided on the piston rod that can advance and retreat inside the cylinder in the vertical direction, and swinging with respect to the center line of the outer tube. The rod includes a rod extension portion extending into the inside of the cylinder body and a coil provided inside the cylinder body so that a slide position of the rod extension portion with respect to the cylinder body can be detected. A shock absorber is provided in which the upper end of the rod extension portion is connected to either the lower end of the piston rod or the piston via a connecting mechanism that connects the extension portion and the mating side member.

Further, the connecting mechanism may have a spherical slide bearing.

Further, by sealing between the inner peripheral surface of the cylinder and the outer peripheral surface of the rod extension portion by a sealing member, a gas chamber is formed inside the cylinder, and the coil is formed of the cylinder. It may be provided in the gas chamber.

INDUSTRIAL APPLICABILITY The present invention can provide a shock absorber provided with a stroke sensor having enhanced durability of the rod extension portion.

It is a side view of the motorcycle which mounted the front fork with the shock absorber according to the Example. It is a side view which cross-sections the main part of one of the two shock absorbers (the first leg and the second leg) which make up the front fork shown in FIG. It is an enlarged cross-sectional view around the cylinder body and the stroke sensor shown in FIG. It is an enlarged cross-sectional view around the piston and the connecting mechanism shown in FIG. It is sectional drawing of the coil unit of the stroke sensor shown in FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings. The form shown in the attached figure is an example of the present invention, and the present invention is not limited to this form. In the explanation, left and right refer to the left and right based on the occupant in the vehicle, and front and rear refer to the front and rear based on the traveling direction of the vehicle. In the figure, Fr indicates the front, Rr indicates the rear, Up indicates the top, and Dn indicates the bottom.

As shown in FIG. 1, the shock absorber 20 is adopted for a vehicle, for example, and as an example, two shock absorbers constituting a front fork of a motorcycle, which is a kind of saddle-riding vehicle on which an occupant straddles. It can be incorporated as one of (first leg and second leg).

The motorcycle 10 (suspension type vehicle 10) includes a vehicle body 11, an engine 12 (power source 12) supported at the lower center of the vehicle body 11, a front fork 13 provided at the front portion of the vehicle body 11, and the front surface thereof. The front wheels 14 supported by the fork 13, the steering handle 15 connected to the front fork 13, the occupant seat 16 provided in the center of the upper part of the vehicle body 11, and the passenger seat 16 extending rearward from the rear portion of the vehicle body 11 in the vertical direction. A wheel support mechanism 17 represented by a swingable link mechanism or a swing arm, a rear wheel 18 supported by the wheel support mechanism 17, and a rear bridged between the vehicle body 11 and the wheel support mechanism 17. It has a suspension 19 and.

Hereinafter, one shock absorber 20 among the two shock absorbers (first leg and second leg) constituting the front fork 13 will be described in detail.

As shown in FIGS. 2 and 3, the shock absorber 20 has an outer tube 30, an inner tube 40, a cylinder 50, a piston rod 60, and a piston 70 as basic components. That is, the shock absorber 20 has a telescopic structure in which the inner tube 40 can be moved forward and backward with respect to the outer tube 30.

The outer tube 30 is an upper cylindrical member that forms a part of the shock absorber 20, extends in the vertical direction, and the upper end 31 is closed by an upper cap 32 (fork bolt 32). The upper end 31 of the outer tube 30 is a closed end, and the lower end 33 of the outer tube 30 is an open end.

The inner tube 40 is a lower cylindrical member that forms a part of the shock absorber 20, and a part of the inner tube 40 is fitted to the inside of the outer tube 30 so as to be able to advance and retreat in the center line CL direction. The lower end 41 of the inner tube 40 is closed by the bottom cap 42 (bottom bolt 42) and is connected to the wheel side bracket 43. The upper end 44 of the inner tube 40 is an open end, and the lower end 41 of the inner tube 40 is a closed end.

The cylinder 50 is a cylindrical member extending from the lower end 41 of the inner tube 40 (that is, the bottom cap 42) to the inside of the inner tube 40, and is located on the center line CL of the outer tube 30. There is. The lower end 51 of the cylinder 50 is a closed end closed by the bottom cap 42.

The piston rod 60 is a rod-shaped member extending from the upper end 31 of the outer tube 30 (that is, the upper cap 32) to the inside of the cylinder 50, and is located on the center line CL of the outer tube 30. The piston rod 60 is composed of, for example, a pipe.

The piston 70 is integrally provided at the lower end 61 of the piston rod 60 by a screw connection, and can advance and retreat inside the cylinder 50 in the vertical direction. The inside of the cylinder 50 is divided into an upper first liquid chamber 52 and a lower second liquid chamber 53 by a piston 70. For example, oil is contained in the first liquid chamber 52 and the second liquid chamber 53.

Further, the shock absorber 20 includes a cylindrical body 80 and a stroke sensor 90.

The cylinder 80 is a cylindrical member extending from the lower end 41 of the inner tube 40 (that is, the bottom cap 42) to the inside of the cylinder 50, and is located on the center line CL of the outer tube 30. There is. The lower end 81 of the tubular body 80 is a closed end. The upper end 82 of the cylinder 80 is an open end open to the inside of the cylinder 50.

The stroke sensor 90 has a rod extension portion 100 (sensor core portion 100) and a coil unit 130.

The rod extension portion 100 is a rod-shaped conductor extending from the lower end 61 of the piston rod 60 or the piston 70 to the inside of the tubular body 80, and is located on the center line CL of the outer tube 30. The rod extension 100 is preferably composed of a pipe whose upper end 101 is closed.

More specifically, as shown in FIGS. 2 and 4, the upper end 101 of the rod extension portion 100 is connected to the lower end 61 of the piston rod 60 or the piston 70 via the connecting mechanism 110. In this embodiment, the upper end 101 of the rod extension portion 100 is connected to the piston 70 by the connecting mechanism 110, but the present invention is not limited to this.

The connecting mechanism 110 connects the upper end 101 of the rod extension portion 100 to the piston 70 so as to swing in a direction intersecting the center line CL of the outer tube 30. The connecting mechanism 110 preferably has a configuration including a spherical slide bearing 111. The spherical slide bearing 111 is a bearing whose basic components are an outer ring 112 having a concave spherical surface portion 112a on the inner peripheral surface and an inner ring 113 having a convex spherical surface portion 113a sliding on the concave spherical surface portion 112a on the outer peripheral surface. be.

For example, the connecting mechanism 110 has a spherical plain bearing 111 and a bolt 114. The outer ring 112 of the spherical plain bearing 111 is attached to the lower part of the piston 70. The inner ring 113 of the spherical plain bearing 111 is attached to the end surface of the upper end 101 of the rod extension portion 100 by the bolt 114. As a result, the upper end 101 of the rod extension portion 100 is connected to the piston 70 by the connecting mechanism 110. By adopting this spherical slide bearing 111, the rod extension portion 100 can easily swing with respect to the center line CL.

It is particularly preferable that the spherical plain bearing 111 is a self-aligning spherical plain bearing. Due to the self-alignment type, the radial load acting in the direction intersecting the center line CL and the thrust load (axial load) acting in the axial direction of the rod extension portion 100 can be supported at the same time. Therefore, even when a bending force acts on the rod extension portion 100, the sliding motion can be performed more smoothly.

An example of a product using this spherical slide bearing 111 is a product Pyroball (trade name "PILLO BALL") manufactured by Nippon Thompson Co., Ltd.

As shown in FIG. 2, the length of the cylinder 80 is shorter than (1) the cylinder 50, and (2) the length at which the rod extension 100 does not come out of the cylinder 80 even when the shock absorber 20 is fully extended. In addition, (3) the cylinder body 80 is set to a length that does not come into contact with the piston 70 and the connecting mechanism 110 when the shock absorber 20 is shortened to the maximum.

As shown in FIGS. 2 and 3, a cylindrical head portion 120 is provided at the upper end 82 of the cylindrical body 80. More specifically, the head portion 120 is located concentrically with the tubular body 80.

The lower half of the head portion 120 is fitted and screwed to the outer peripheral surface of the upper end 82 of the tubular body 80, and includes a first seal member 121. The first sealing member 121 seals between the outer peripheral surface of the tubular body 80 and the inner peripheral surface of the head portion 120.

The upper half of the head portion 120 is fitted to the rod extension portion 100, and includes a bearing 122 and a second seal member 123. The bearing 122 supports the lower portion of the rod extension portion 100 so as to be movable in the vertical direction. The second sealing member 123 seals between the outer peripheral surface of the rod extension portion 100 and the inner peripheral surface of the head portion 120.

As a result, the tubular body 80 supports the lower portion of the rod extension portion 100 so as to be movable in the vertical direction. The inner peripheral surface of the tubular body 80 and the outer peripheral surface of the rod extension portion 100 are sealed by the sealing members 121 and 123. Therefore, the liquid (for example, oil) of the second liquid chamber 53 does not flow into the internal space 124 of the tubular body 80, and the gas exists in the internal space 124. Hereinafter, the internal space 124 of the tubular body 80 will be referred to as a “gas chamber 124”.

The upper portion of the tubular body 80 or the head portion 120 is preferably supported in the radial direction (direction intersecting the center line CL) by the inner peripheral surface of the inner tube 40. As a result, when a radial load acts on the tubular body 80 from the rod extension portion 100 via the bearing 122, the tubular body 80 can be supported by the inner tube 40. Even if the bending rigidity of the tubular body 80 is reduced by that amount, the durability against the bending force can be improved.

Further, the head portion 120 may be integrally configured with the tubular body 80.

As shown in FIGS. 3 and 5, the coil unit 130 is fitted inside the tubular body 80 and housed in the tubular body 80. The coil unit 130 is provided on the coil 132, the cylindrical support 131 (coil bobbin 131) that supports the coil 132, the cap portion 133 that closes the lower end of the support 131, and the upper end of the support 131. Includes an annular cover portion 134 provided. The coil 132 is wound around the support 131.

The support 131 is positioned concentrically with respect to the center line CL of the outer tube 30, and is positioned in the center line CL direction by restricting movement in the center line CL direction by the cap portion 133 and the cover portion 134. Has been done. The rod extension portion 100 (sensor core portion 100) can move forward and backward in the support 131.

The coil 132 can detect the position of the rod extension portion 100 with respect to the tubular body 80 in the center line CL direction (center line CL direction of the outer tube 30). The coil 132 is provided in the gas chamber 124 together with the support 131. The coil 132 has a characteristic that the inductance increases as the temperature rises.

The cap portion 133 is provided with a terminal board 135. The terminal board 135 is provided with a terminal 136 to which the coil 132 is connected. The cable harness 137 connected to the terminal 136 extends to the outside through the bottom side cap 42 and the wheel side bracket 43, and is connected to a control unit (not shown). The portion of the wheel-side bracket 43 from which the cable harness 137 is pulled out is sealed by the grommet 138.

Next, the operation of the stroke sensor 90 will be described. As shown in FIGS. 3 and 5, the insertion length (fitting length) of the rod extension portion 100 with respect to the coil 132 changes as the shock absorber 20 expands and contracts. At this time, when an alternating current is flowing through the coil 132, an eddy current is generated in the rod extension portion 100 so as to cancel the fluctuation of the magnetic field. The inductance of the coil 132 changes due to the eddy current. The stroke amount of the shock absorber 20 can be detected by this change in inductance. For example, the stroke amount can be converted from the change amount of the inductance to obtain the stroke amount.

The description of the above embodiment can be summarized as follows.
As shown in FIGS. 2 and 3, the shock absorber 20 has an outer tube 30 having an upper end 31 as a closed end and a lower end 33 as an open end, and an upper end 44 as an open end and a lower end 41 as a closed end. An inner tube 40 that is partially fitted to the inside of the outer tube 30 so as to be able to advance and retreat, a cylinder 50 that extends from the lower end 41 of the inner tube 40 to the inside of the inner tube 40, and the inner tube. A tubular cylinder 80 extending from the lower end 41 of the 40 to the inside of the cylinder 50, a piston rod 60 extending from the upper end 31 of the outer tube 30 to the inside of the cylinder 50, and the piston rod 60. A piston 70 that can move forward and backward in the cylinder 50 and a rod extension 100 that extends into the cylinder 80 so as to swing with respect to the center line CL of the outer tube 30. And the coil 132 provided inside the cylinder 80 so that the slide position of the rod extension 100 with respect to the cylinder 80 can be detected, and the rod extension 100 and the mating member are connected to each other. The upper end 101 of the rod extension portion 100 is connected to either the lower end 61 of the piston rod 60 or the piston 70 via the connecting mechanism 110.

As described above, the stroke sensor 90 includes the rod extension portion 100 and the coil 132. When a bending force (radial load) acts on the shock absorber 20, the bending force may also act on the rod extension portion 100. The lower end 102 of the rod extension 100 is supported by the bearing 122 so as to be able to move forward and backward in the vertical direction, while the movement in the radial direction is restricted. Therefore, in the conventional shock absorber, the bending stress may be concentrated on the rod extension portion 100.

On the other hand, in the present invention, the upper end 101 of the rod extension portion 100 is configured to be swingable in the direction (diameter direction) intersecting the center line CL by the connecting mechanism 110. Therefore, when a bending force acts on the rod extension portion 100, the rod extension portion 100 can swing in the radial direction with the upper end 101 as a reference. As a result, bending stress is less likely to be concentrated on the rod extension portion 100 as compared with the form having no connecting mechanism 110. As a result, according to the present invention, it is possible to provide a shock absorber 20 including a stroke sensor 90 having improved durability of the rod extension portion 100.

Further, as shown in FIG. 3, the shock absorber 20 is described by sealing between the inner peripheral surface of the tubular body 80 and the outer peripheral surface of the rod extension portion 100 by the sealing members 121 and 123. A gas chamber 124 is formed inside the tubular body 80, and the coil 132 is provided in the gas chamber 124 in the tubular body 80.

As described above, in the shock absorber 20, the coil 132 is arranged in the gas chamber 124, which is less susceptible to temperature changes than the liquid chamber 53 (second liquid chamber 53). Since the specific heat of air existing in the gas chamber 124 is larger than that of oil, the temperature change is slower than that of oil. Therefore, by adopting such a form, the coil 132 has a characteristic that the inductance increases as the temperature rises, but the temperature rise of the liquid (oil) in the shock absorber 20 causes the inductance characteristic of the coil 132. The effect can be eliminated as much as possible. As a result, it is possible to make it difficult for an error to occur in the stroke amount detected by the stroke sensor 90, so that it is possible to provide the shock absorber 20 having improved temperature characteristics of the stroke sensor 90.

Moreover, it is not necessary to add a capacitor for temperature compensation to the detection circuit of the stroke sensor 90. Therefore, since the number of parts does not increase, the price of the shock absorber 20 can be reduced.

The present invention is not limited to the examples as long as the actions and effects of the present invention are exhibited.
For example, the shock absorber 20 according to the present invention can be applied not only to motorcycles but also to tricycles, buggies and the like. That is, it can be mounted on saddle-riding vehicles other than motorcycles.

The shock absorber 20 of the present invention is suitable for being mounted as a rear cushion on a saddle-riding vehicle such as a motorcycle.

13 Front fork 20 Shock absorber 30 Outer tube 31 Upper end (closed end)
33 Lower end (open end)
40 Inner tube 41 Lower end (closed end)
44 Upper end (open end)
50 Cylinder 51 Lower end 52 1st liquid chamber 53 2nd liquid chamber 60 Piston rod 61 Lower end 70 Piston 80 Cylinder 81 Lower end (closed end)
82 Upper end (open end)
90 Stroke sensor 100 Rod extension 101 Upper end 102 Lower end 110 Connection mechanism 111 Spherical plain bearing 120 Head 122 First seal member 123 Second seal member 124 Gas chamber 130 Coil unit 132 Coil CL Outer tube center line

Claims (3)

An outer tube with the upper end as the closed end and the lower end as the open end,
An inner tube having an open end at the upper end and a closed end at the lower end, and a part of the outer tube that is fitted to the inside of the outer tube so as to be able to move forward and backward.
A cylinder extending from the lower end of the inner tube to the inside of the inner tube,
A tubular body extending from the lower end of the inner tube to the inside of the cylinder,
A piston rod extending from the upper end of the outer tube to the inside of the cylinder,
A piston provided on the piston rod that can move up and down inside the cylinder,
A rod extension portion extending into the inside of the cylinder so as to be swingable with respect to the center line of the outer tube,
Includes a coil provided inside the cylinder so that the slide position of the rod extension with respect to the cylinder can be detected.
The upper end of the rod extension is connected to either the lower end of the piston rod or the piston via a connecting mechanism that connects the rod extension and the mating member.
Buffer. The shock absorber according to claim 1, wherein the connecting mechanism has a spherical plain bearing. A gas chamber is formed inside the cylinder by sealing between the inner peripheral surface of the cylinder and the outer peripheral surface of the rod extension portion by a sealing member.
The coil is provided in the gas chamber in the cylinder.
The shock absorber according to claim 1 or 2.

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