Front fork

Abstract

A front fork (10) comprises: a first cylindrical body (30) configured by a cylindrical body having a closed upper end; a second cylindrical body (40) which is provided coaxially with and below the first cylindrical body (30), partially overlaps the first cylindrical body (30), and has a closed lower end; a hydraulic jack (60) which is provided inside the first cylindrical body (30) or the second cylindrical body (40) and is capable of adjusting, by hydraulic pressure, the length from a bottom (30a) of the first cylindrical body (30) to a bottom (40a) of the second cylindrical body (40); an actuator (17) that operates when energized; and a pump (50) that operates the hydraulic jack (60) when the actuator (17) is operated. The actuator (17) is directly connected to the pump (50).

Description

Front fork

[0001] The present invention relates to a front fork.

[0002] A front fork is provided that damps vibrations and the like received from the road surface from the front wheel of a saddle-type vehicle toward the vehicle body. As a prior art related to the front fork, there is a technique disclosed in Patent Document 1.

[0003] As shown in Patent Document 1, the front fork is an upright front fork, and a jack chamber for adjusting the seat height of a saddle-type vehicle is provided inside an inner tube provided at the upper part.

[0004] Japanese Patent Application Laid-Open No. 2017-178176

[0005] For example, it is conceivable to operate a pump by an actuator, adjust the amount of oil in the jack chamber, and arbitrarily adjust the height of a saddle-type vehicle. At this time, since there is a limit to the mounting space for parts of the saddle-type vehicle, it is desired to suppress the enlargement of the front fork as much as possible.

[0006] An object of the present invention is to provide a front fork that is small while mounting an actuator and a pump.

[0007] Hereinafter, the present disclosure will be described.

[0008] According to the present disclosure, a first cylinder body constituted by a cylinder body with one end closed, a second cylinder body provided coaxially with the first cylinder body on the other side of the first cylinder body, and having one end overlapping the first cylinder body and the other end closed, an actuator that operates by energization, a pump that is connected to the actuator and circulates oil when the actuator operates, and a hydraulic jack provided inside the first cylinder body or the second cylinder body and capable of adjusting the length from the bottom of the first cylinder body to the bottom of the second cylinder body by the hydraulic pressure of the oil circulated by the pump are provided.

[0009] According to the present invention, it is possible to provide a compact front fork that incorporates an actuator and a pump.

[0010] This is a cross-sectional view of a shock absorber used in a front fork according to an embodiment. This is an enlarged view of part 2 of Figure 1. This is a cross-sectional view taken along line 3-3 of Figure 2. This is an enlarged view of part 4 of Figure 1.

[0011] Embodiments of the present invention will be described below with reference to the attached drawings. Note that the embodiments shown in the attached drawings are examples of the present invention, and the present invention is not limited to these embodiments.

[0012] <Example> Refer to Figure 1. Figure 1 shows a front fork 10. The front fork 10 is a shock absorber provided on the left and right sides of the front wheel of a saddle-type vehicle. Note that the front fork 10 of the present invention only needs to be provided on at least one of the left and right sides, and the other front fork may be a front fork with a different configuration from the front fork according to the present invention.

[0013] The front fork 10 has an outer tube, which is a first cylindrical body 30, at the top and an inner tube, which is a second cylindrical body 40, at the bottom. For example, the front fork 10 is an inverted type front fork in which a part of the second cylindrical body 40 is located inside the first cylindrical body 30.

[0014] Furthermore, the front fork 10 is not limited to an inverted type; it may also be an upright type in which the tip of the first cylinder positioned at the top is inside the tip of the second cylinder positioned at the bottom. In this case, the first cylinder becomes the inner tube, and the second cylinder becomes the outer tube.

[0015] The front fork 10 includes, in addition to the first cylinder 30 and the second cylinder 40, a spring 13 that biases the first cylinder 30 and the second cylinder 40 in a direction that separates them, a cylindrical inner cylinder 14 that extends from the first cylinder 30 toward the second cylinder 40, a cylindrical piston rod 15 that is fixed to the second cylinder 40 and extends into the interior of the inner cylinder 14, and a piston 16 that is fixed to the tip of the piston rod 15 and generates a damping force when the first cylinder 30 is displaced relative to the second cylinder 40. The device includes an actuator 17 located inside the first cylindrical body 30 that rotates when energized, a pump 50 connected to the actuator 17 that circulates oil when the actuator 17 is activated, a hydraulic jack 60 that operates when the pump 50 is activated and adjusts the length from the bottom 30a of the first cylindrical body 30 to the bottom 40a of the second cylindrical body 40, and a cylindrical liquid delivery cylinder 22 that extends from the pump 50 toward the bottom 40a of the second cylindrical body 40 through which oil passes.

[0016] Refer to Figure 2. The pump housing 23, which houses the pump 50, is fastened to the first cylindrical body 30. A cylindrical spacer 24 is provided inside the pump housing 23, and the space partitioned by the pump 50 and the spacer 24 is the internal flow path R1 of the housing through which oil flows.

[0017] The support member 25, which supports the inner cylinder 14 and the liquid delivery cylinder 22, is sandwiched and fixed between the pump housing 23 and the pump 50. An internal flow path R2 for oil is formed inside the support member 25. The inner cylinder 14 is screw-fastened to the support member 25, and the end of the liquid delivery cylinder 22 is inserted into the support member 25.

[0018] A connecting member 27, which is rotatably supported by a bearing 26, is connected to the shaft portion 17a, which is the rotation axis of the actuator 17. A transmission member 28, which transmits the rotation of the actuator 17, is fixed to the connecting member 27. The transmission member 28 has a hexagonal prism shape and is connected to the pump 50. As a result, the rotation of the actuator 17 is transmitted to the pump 50, and the pump 50 operates.

[0019] Refer to Figure 1. The lower end of the hydraulic jack 60 is provided with a spring support portion 29 that receives the upper end of the spring 13. The spring support portion 29 moves up and down together with the hydraulic jack 60.

[0020] The first cylinder 30, the second cylinder 40, the spring 13, the inner cylinder 14, the piston rod 15, the piston 16, the actuator 17, the pump 50, the hydraulic jack 60, the liquid delivery cylinder 22, the pump housing 23, the spacer 24, the support member 25, the bearing 26, the connecting member 27, the transmission member 28, and the spring receiving part 29 are arranged coaxially. Hereinafter, the axis common to these components will be referred to as the axis CL of the first cylinder 30.

[0021] The first cylindrical body 30 has a first main body portion 31 which is formed in a cylindrical shape, and a first lid portion 32 which closes the upper end of the first main body portion 31. The first lid portion 32 is screw-fastened to the inner circumferential surface of the first main body portion 31.

[0022] A connector 32a for inserting a power harness is formed at the upper end of the first cover portion 32. Inside the first cover portion 32, a circuit board 32b is provided, which is powered by the connector 32a and controls the actuator 17. In other words, the connector 32a and the circuit board 32b are integrally provided on the first cover portion 32.

[0023] The second cylindrical body 40 has a second main body portion 41 which is formed in a cylindrical shape, and a second lid portion 42 which closes the lower end of the second main body portion 41.

[0024] The spring 13 is made of a coil spring, with its upper end biasing the first cylindrical body 30 upward and its lower end biasing the second cylindrical body 40 downward. As a result, the first cylindrical body 30 and the second cylindrical body 40 are biased to move apart from each other.

[0025] The piston rod 15 has its lower end fixed to the second cover portion 42 and its upper end is threaded.

[0026] A well-known piston can be used for the piston 16. When the front wheel rides over a bump or other obstacle in the road surface, the second cylinder 40 is displaced relative to the first cylinder 30. More specifically, it compresses and extends along the axis CL of the first cylinder 30. At this time, oil passes through the inside of the piston 16, generating a damping force. Leaf springs for adjusting the damping force may be provided on the upper and lower surfaces of the piston 16.

[0027] The actuator 17 is directly supported by the first cover portion 32. The actuator 17 is an electric motor whose shaft portion 17a rotates when power is supplied via the circuit board 32b.

[0028] Refer to Figure 2. Pump 50 is, for example, an external gear pump as a gear pump. Pump 50 has a pump housing 51 which is a housing formed by two separable members, a drive gear 52 which is a gear housed in the pump housing 51 and through which a transmission member 28 passes through the center, and a driven gear 53 which meshes with the drive gear 52 and rotates as the drive gear 52 rotates. Note that an internal gear pump as a gear pump can be used for pump 50. A vane pump or a piston pump can also be used.

[0029] As the drive gear 52 rotates, the driven gear 53 rotates, and oil is pumped in the area between each gear 52, 53 and the pump housing 51. The direction of oil circulation changes depending on the direction in which the drive gear 52 and the driven gear 53 rotate.

[0030] Refer to Figure 3. The pump 50 further includes a first valve 54, which is a check valve that allows oil to flow from top to bottom (towards the back of the page) when a predetermined hydraulic pressure is applied, and a second valve 55, which is a check valve that allows oil to flow from bottom to top (towards the front of the page) when a predetermined hydraulic pressure is applied.

[0031] Refer to Figure 2. The pump housing 51 has a first housing 51a in which the drive gear 52 and driven gear 53 are housed, and a second housing 51b superimposed on the first housing 51a. Inside the pump housing 51, there is a housing internal passage R3 through which oil can pass. The housing internal passage R3 is connected to both the storage internal passage R1 and the support member internal passage R2, including parts not shown.

[0032] The second valve 55 includes a valve body 55a provided inside the pump housing 51 and having a passage through which oil can pass; a push rod 55b whose tip faces the valve body 55a and which is displaceable up and down; a second valve spring portion 55c that biases the push rod 55b downward; and a valve body 55d that is biased downward by contact with the tip of the push rod 55b and closes a part of the passage.

[0033] Refer to Figure 3 as well. The configuration of the first valve 54 may be the same as that of the second valve 55, or it may be a different configuration.

[0034] Refer to Figure 4. The hydraulic jack 60 includes a substantially cylindrical outer fixing portion 61 supported by the first lid portion 32 (see Figure 1), a substantially cylindrical inner fixing portion 62 supported by a support member 25 (see Figure 1) and provided along the inner circumferential surface of the outer fixing portion 61, a guide member support portion 63 fixed to the tip of the inner fixing portion 62, a cylindrical guide member 64 fixed to the outer circumference of the guide member support portion 63, a displacement portion 65 that abuts the outer circumferential surface of the guide member 64 and is displaceable in the vertical direction, and a position sensor 66 provided in the space between the outer fixing portion 61 and the inner fixing portion 62 for detecting the amount of displacement of the hydraulic jack 60 (position of the displacement portion 65).

[0035] Between the inner fixing portion 62 and the inner cylindrical body 14, a jack portion passage R4 is formed, which is a passage through which oil passes. The jack portion passage R4 is connected to the support member internal passage R2.

[0036] The area enclosed by the inner fixing part 62, the inner cylinder 14, and the displacement part 65 is the jack chamber JR, which is filled with oil. When oil is supplied to the jack chamber JR, the displacement part 65 is pushed down by hydraulic pressure against the biasing force of the spring 13. Relatively, the first cylinder 30 is lifted, and the height of the saddle-type vehicle increases. On the other hand, when the oil is sucked out of the jack chamber JR, the displacement part 65 is pushed up by the biasing force of the spring 13. Relatively, the first cylinder 30 is lowered, and the height of the saddle-type vehicle decreases.

[0037] The position sensor 66 includes a coil and is energized via the circuit board 32b (see Figure 1). When the displacement unit 65 is displaced, the magnetic field changes. This information is sent to the circuit board 32b. The circuit board 32b detects the position of the displacement unit 65 from pre-mapped information. The height of the saddle-type vehicle can be detected by the position of the displacement unit 65.

[0038] Refer to Figure 1. Note that the actuator 17 and the pump 50 do not necessarily have to be located inside the first cylinder 30 or the second cylinder 40. In this case, the case housing the actuator 17 and the pump 50 can be located adjacent to either cylinder 30 or 40.

[0039] Furthermore, the actuator 17, pump 50, and hydraulic jack 60 may be provided in the second cylindrical body 40 (especially the lower part).

[0040] Furthermore, in this embodiment, the oil used to generate damping force is used as the operating oil for the hydraulic jack 60, but other oils, such as the lubricating and cooling oil used in the front fork 10, may also be used. In addition, a separate reservoir for the operating oil of the hydraulic jack 60 may be provided.

[0041] The operation of the front fork 10 described above will now be explained.

[0042] Refer to Figure 2. When raising the ride height of the saddle-type vehicle, the circuit board 32b (see Figure 1) energizes the actuator 17, causing the drive gear 52 to rotate in one direction. This draws oil up through the inside of the fluid supply cylinder 22. The drawn-up oil is sent to the internal passage R1 of the storage section.

[0043] Referring also to FIG. 3, when oil is sent into the internal flow path R1 of the storage section, the first valve 54 is pushed down, and the oil flows in the order of the internal flow path R3 in the housing, the internal flow path R2 in the support member, and the jack section flow path R4 (see FIG. 4).

[0044] Referring to FIG. 4, the oil that has flowed into the jack section flow path R4 flows into the jack chamber JR and pushes down the displacement section 65. As a result, the vehicle height increases.

[0045] Referring to FIG. 2, when lowering the vehicle height of the saddle-type vehicle, the circuit board 32b (see FIG. 1) energizes the actuator 17 to rotate the drive gear 52 in the other direction opposite to one direction. As a result, the second valve 55 rises and the internal flow path R3 in the housing is opened.

[0046] Referring to FIG. 4, when the drive gear 52 is rotating in the other direction, the oil in the jack chamber JR is sucked up and rises through the jack section flow path R4. As the oil in the jack chamber JR decreases, the displacement section 65 is pushed up by the biasing force of the spring 13, and the vehicle height decreases.

[0047] Referring to FIG. 2, the oil that has risen through the jack section flow path R4 (see FIG. 4) passes through the support member internal flow path R2 and the housing internal flow path R3 and is sent downward from the liquid delivery cylinder 22.

[0048] The front fork 10 described above is summarized below.

[0049] Refer to Figure 1. Firstly, the front fork 10 comprises a first cylindrical body 30, which is composed of a cylindrical body with one end (upper end) closed; a second cylindrical body 40, which is provided coaxially with the first cylindrical body 30 and on the other side (lower side), with one end (upper end) overlapping the first cylindrical body 30 and the other end (lower end) closed; an actuator 17 that operates when electricity is applied; a pump 50 connected to the actuator 17, which circulates oil when the actuator 17 operates; and a hydraulic jack 60 provided inside the first cylindrical body 30 (or the second cylindrical body 40), which can adjust the length from the bottom 30a of the first cylindrical body 30 to the bottom 40a of the second cylindrical body 40 by the hydraulic pressure of the oil circulated by the pump 50. Because the actuator 17 is directly connected to the pump 50, these components can be made compact. A compact front fork 10 can be provided while still incorporating the actuator 17 and the pump 50.

[0050] Here, "direct" means that the actuator 17 and the pump 50 are installed adjacent to each other and connected, and also includes cases where they are connected via a coupling or where the actuator 17 and the pump 50 are arranged in parallel.

[0051] Secondly, in the first front fork 10, the actuator 17 and the pump 50 are located inside the same cylindrical body (first cylindrical body 30) in which the hydraulic jack 60 is installed. This allows the actuator 17 and the pump 50 to be located in close proximity to the hydraulic jack 60. This shortens the time from when the actuator 17 is activated until the hydraulic jack 60 is activated. In other words, it improves responsiveness. The same applies when the hydraulic jack 60, actuator 17, and pump 50 are all located in the second cylindrical body 40.

[0052] Thirdly, in the second front fork 10, the hydraulic jack 60, actuator 17, and pump 50 are provided on the upper part of the first cylindrical body 30 (the upper part in the direction of gravity, which is one end). The lower part of the front fork 10 is close to the wheel and is therefore susceptible to vibrations from the road surface. By providing the hydraulic jack 60, actuator 17, and pump 50 on the upper part of the front fork 10, the effects of vibrations on these components can be suppressed, and the hydraulic jack 60 can be operated more reliably.

[0053] Fourthly, the third front fork 10 further includes a fluid delivery cylinder 22 that extends from the pump 50 toward the bottom 40a of the second cylindrical body 40, and through which oil flows when the pump 50 is operated. When supplying fluid toward the hydraulic jack 60, the oil accumulated at the bottom can be used, eliminating the need to provide space at the top for storing oil, thus allowing the front fork 10 to be made smaller.

[0054] Refer to Figure 2. Fifth, in any of the second to fourth front forks 10, the hydraulic jack 60 has a position sensor 66 for detecting the amount of operation of the hydraulic jack 60. By having the position sensor 66, the hydraulic jack 60 can be operated more reliably. The same applies when the hydraulic jack 60, actuator 17, and pump 50 are provided in the second cylindrical body 40.

[0055] Refer to Figure 1 as well. Sixth, the fifth front fork 10, which has a circuit board 32b that operates the actuator 17 and receives information detected by the position sensor 66, is provided on the first cylindrical body 30. The hydraulic jack 60, actuator 17, pump 50, position sensor 66 and circuit board 32b can be provided close to each other. The hydraulic jack 60 can be operated with higher responsiveness and more reliably. The same applies when the hydraulic jack 60, actuator 17, pump 50, position sensor 66 and circuit board 32b are provided on the second cylindrical body 40.

[0056] Seventh, in any of the first to sixth front forks 10, the oil supplied to the pump 50 is oil for generating damping force. Since the oil for generating damping force is used as the operating oil for the hydraulic jack 60, the space required for filling the oil is minimized, which contributes to miniaturizing the front fork 10.

[0057] Eighth, the front fork 10 is one of the first to seventh, and the pump 50 is a gear pump. The hydraulic jack 60 can be extended and compressed simply by switching between forward and reverse rotation. It is preferable that the hydraulic jack 60 can be extended and retracted with a simple configuration.

[0058] Ninthly, in the eighth front fork 10, the rotation axis (shaft portion 17a) of the actuator 17 and the rotation axis (transmission member 28) of the drive gear 52 of the pump 50 are coaxial with (coincident with) the axis CL of the first cylindrical body 30. By arranging the drive components on the axis CL of the first cylindrical body 30, the generation of vibrations when these components are operating can be suppressed.

[0059] Tenth, in any of the second to ninth front forks 10, the actuator 17 and the pump 50 are provided along the axis CL of the first cylindrical body 30. The actuator 17 and the pump 50 can be compactly arranged around the axis CL of the first cylindrical body 30, contributing to miniaturization of the front fork 10.

[0060] Eleventh, the second front fork 10, in which the hydraulic jack 60, actuator 17, and pump 50 are located at the lower part of the second cylindrical body 40. The lower part of the front fork 10 has relatively more space, making it easier to arrange the components.

[0061] Furthermore, the present invention is not limited to the examples provided, provided that it achieves the functions and effects of the present invention.

[0062] The front fork of the present invention is suitable for saddle-type vehicles.

[0063] 10...Front fork 17...Actuator 22...Liquid delivery cylinder 30...First cylinder, 30a...Bottom of the first cylinder 32a...Circuit board 40...Second cylinder, 40a...Bottom of the second cylinder 50...Pump 60...Hydraulic jack 66...Position sensor CL...Axis of the first cylinder

Claims

1. A front fork comprising: a first cylindrical body consisting of a cylindrical body with one end closed; a second cylindrical body provided coaxially with the first cylindrical body and on the other side thereof, with one end overlapping the first cylindrical body and the other end closed; an actuator that operates when electricity is supplied; a pump connected to the actuator and which circulates oil when the actuator is operated; and a hydraulic jack provided inside the first cylindrical body or the second cylindrical body, which can adjust the length from the bottom of the first cylindrical body to the bottom of the second cylindrical body by the hydraulic pressure of the oil circulated by the pump.

2. The front fork according to claim 1, wherein the actuator and the pump are provided inside the same cylindrical body, which is either the first cylindrical body or the second cylindrical body, in which the hydraulic jack is provided.

3. The front fork according to claim 2, wherein the hydraulic jack, the actuator, and the pump are provided at the upper end in the direction of gravity, which is one end of the first cylindrical body.

4. The front fork according to claim 3, further comprising a liquid supply cylinder extending from the pump toward the bottom of the second cylinder, through which oil flows when the pump is operated.

5. The front fork according to claim 2, wherein the hydraulic jack has a position sensor for detecting the amount of operation of the hydraulic jack.

6. The front fork according to claim 5, wherein a circuit board for operating the actuator and receiving information detected by the position sensor is provided in the same cylindrical body as the hydraulic jack, which is either the first or second cylindrical body.

7. The front fork according to claim 1, wherein the oil supplied to the pump is an oil for generating damping force.

8. The front fork according to claim 1, wherein the pump is a gear pump.

9. The front fork according to claim 8, wherein the rotation axis of the actuator and the rotation axis of one of the gears of the pump are coaxial with the axis of the first cylindrical body.

10. The front fork according to claim 2, wherein the actuator and the pump are provided along the axis of the first cylindrical body.

11. The front fork according to claim 2, wherein the hydraulic jack, the actuator, and the pump are provided at the lower end of the other end of the second cylinder in the direction of gravity.

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