JP2016038071A - Front fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front fork capable of attaining an appropriate attenuation force even if it is set to a uniflow type.SOLUTION: This invention comprises a rod 4 having one end connected to a cap member 2 and the other end fed-in or fed-out to/from a cylinder 3; a piston 5 connected to the other end of the rod 4 to define an inner side of the cylinder 3 into an extending side chamber R1 and a compressing side chamber R2; a base member 6 defining a reservoir R3 out of the cylinder 3 and a compression side chamber R2; the first passage 5a formed at the piston 5 allowing only a flow of fluid from the compression side chamber R2 to the extending chamber R1; the second passage 6a allowing only a flow of fluid from the reservoir R3 to the extending chamber R1; an attenuation passage MP having one end at the extension side chamber R1 opened to the side of the rod 4, passing through the rod 4 and a cap member 2 to communicate with the extending side chamber R1 and the reservoir R3; and an attenuation force generating member V applying a resistance against the flow of fluid passing through the attenuation passage MP and changing the resistance by a solenoid Sol.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a front fork.

  Among front forks used in straddle-type vehicles such as motorcycles and tricycles, a telescopic cylinder member including a vehicle body side tube and a wheel side tube, a cap member attached to the vehicle body side tube, and a wheel side tube A cylinder provided on the inner side of the cylinder, one end connected to the cap member and the other side connected to the cylinder, and the other end of the rod connected to the other end and slidably inserted into the cylinder. A piston that divides into the expansion side chamber and the pressure side chamber on the opposite rod side, a first passage that communicates the extension side chamber and the compression side chamber, and opens the first passage in the compression stroke, and the fluid flowing from the compression side chamber to the extension side chamber A first check valve that allows the flow, a second passage that communicates the reservoir formed outside the cylinder and the pressure side chamber, and opens the second passage in the extension stroke, and is directed from the reservoir to the pressure side chamber. A second check valve that allows fluid flow, a damping passage that communicates the extension side chamber and the reservoir through the rod, and attached to the cap member to provide resistance to the fluid flow through the damping passage; Some have a damping force generating member that changes this resistance with a solenoid and are set to a uniflow type (for example, Patent Document 1).

  According to such a uniflow type front fork, the fluid can circulate in one direction in this order through the compression side chamber, the extension side chamber, and the reservoir in both the expansion and compression strokes. In the extension stroke of the front fork, the communication between the extension side chamber and the compression side chamber is interrupted, and the fluid in the extension side chamber passes through the attenuation passage and moves to the reservoir. On the contrary, in the compression stroke of the front fork, the communication between the compression side chamber and the reservoir is cut off, and the fluid corresponding to the volume of the rod that has entered the cylinder passes through the damping passage and moves to the reservoir. In other words, according to the above configuration, the fluid passes through the attenuation passage in both the expansion and compression strokes, so that the damping force in the expansion stroke and the compression stroke can be changed with a single solenoid.

  Furthermore, in the extension stroke of the front fork, a maximum amount of fluid of the reduced extension side chamber can pass through the damping passage, and in the compression stroke, a maximum amount of fluid of the rod volume that has entered the cylinder. Can pass through the attenuation path. Therefore, in a biflow type front fork in which the bidirectional flow between the extension side chamber and the compression side chamber and the bidirectional flow between the compression side chamber and the reservoir are allowed, a damping passage that communicates the extension side chamber and the reservoir is provided and passes through the attenuation passage. In the uniflow type front fork, the flow rate of the fluid passing through the attenuation passage can be increased as compared with the case where the fluid flow is adjusted by a solenoid (for example, Patent Document 2). For this reason, the area | region of the piston speed which can adjust damping force can be expanded.

Japanese Patent No. 2695816 Japanese Patent Laid-Open No. 01-195195

  Here, in the uniflow type front fork disclosed in Japanese Patent No. 2695816, as shown in FIG. 4, the first passage 501 that communicates the expansion side chamber R1 and the compression side chamber R2 defined by the piston 500 is provided with the rod 400. The passage 401 has one end opened to the pressure side chamber R2 and one end opened to the lower portion of the rod 400 and the other end opened to the passage 401. A first check valve 403 that opens in the compression stroke and allows the flow of fluid from the pressure side chamber R2 toward the expansion side chamber R1 is provided on the pressure side chamber R2 side of the orifice 401 in the passage 401.

  The attenuation passage MP0 that connects the extension side chamber R1 and the reservoir R3 also includes the passage 401, the orifice 402, and an orifice (not shown) that opens to the upper side of the rod 400. A damping force generating member is provided downstream of the orifice.

  That is, in the front fork, the first passage 501 and the attenuation passage MP0 share a part of the pipeline (the orifice 402 and the passage 401). For this reason, in the compression stroke of the front fork, when the hydraulic oil in the pressure side chamber R2 opens the first check valve 403 and flows into the rod 400, a part of the hydraulic oil branches and flows into the extension side chamber R1 and the reservoir R3. . However, according to this configuration, since the hydraulic oil cannot flow into the extension side chamber R1 unless it passes through the orifice 402, the hydraulic oil is not sufficiently supplied to the extension side chamber R1 and becomes a negative pressure, thereby obtaining an appropriate damping force. There is a bug that can not be done.

  Accordingly, an object of the present invention is to provide a front fork capable of obtaining an appropriate damping force even when the uniflow type is set.

  In the invention according to claim 1, which solves the above-mentioned problem, the front fork is set to be a uniflow type, and the first passage in which the flow of fluid from the compression side chamber to the extension side chamber is allowed is formed in the piston. One end of the expansion side chamber side of the attenuation passage communicating the pressure side chamber and the pressure side chamber is open to the side portion of the rod.

  According to the configuration, the first passage and the attenuation passage do not share the pipe line, and the extension side chamber can be interposed between the first passage and the attenuation passage. Therefore, in the compression stroke of the front fork, the hydraulic oil in the compression side chamber does not flow directly into the attenuation passage, but always flows through the first passage and the extension side chamber in this order before flowing into the attenuation passage. For this reason, it can suppress that hydraulic oil runs short in the expansion side chamber and becomes a negative pressure in the compression stroke of the front fork.

  According to a second aspect of the present invention, the damping force generating member includes a main valve that provides resistance to a flow of fluid passing through the damping passage, and a back pressure that biases the main valve in the closing direction. A pilot passage for leading the pressure upstream from the main valve to the main valve, a throttle provided in the middle of the pilot passage, and an electromagnetic including a solenoid provided downstream of the throttle in the pilot passage to control the back pressure And a valve.

  According to the said structure, compared with the case where the thrust of a solenoid is made to act on a valve body directly, the resistance by a main valve can be changed with a small thrust. For this reason, even if the flow volume of the fluid which passes a main valve is large, it can prevent that the thrust of a solenoid runs short. Therefore, the damping force can be adjusted even when the piston speed is in the high speed region. Moreover, the enlargement of the solenoid can be suppressed and the cost and weight can be reduced.

  According to a third aspect of the present invention, the rod includes a cylindrical shaft portion and a piston holding portion, and the annular nut portion in which the piston holding portion is screwed onto the outer periphery of the shaft portion; and the nut portion An annular spacer portion extending from the opposite shaft portion side to have a smaller inner diameter than the nut portion, and a hole penetrating in the radial direction is formed, a bottom portion closing the opposite shaft portion side opening of the spacer portion, An attachment portion extending from the center of the bottom portion to the opposite shaft side and having an outer diameter smaller than the bottom portion, the piston is formed in an annular shape and held on the outer periphery of the attachment portion, and a damping passage is provided It passes through the hole, the inside of the spacer part and the inside of the shaft part.

  According to the above configuration, since the inner diameter of the spacer portion is formed smaller than the inner diameter of the nut portion, the hole is prevented from being blocked by the shaft portion screwed into the piston holding portion, and the damping passageway and the extension side chamber are prevented from being blocked. It is possible to easily and reliably prevent communication from being interrupted.

  According to the front fork of the present invention, an appropriate damping force can be obtained even when the uniflow type is set.

It is the front view which notched and showed the principal part of the front fork which concerns on one embodiment of this invention. It is the elements on larger scale which expanded and showed a part of FIG. It is a circuit diagram of a damping force generating member of a front fork according to an embodiment of the present invention. It is the longitudinal cross-sectional view which expanded and showed the principal part of the conventional front fork.

  Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  As shown in FIG. 1, a front fork F according to an embodiment of the present invention is attached to a vehicle body side tube 10 and a telescopic cylinder member 1 that can extend and contract, including a vehicle body side tube 10 and a wheel side tube 11. A cap member 2, a cylinder 3 provided inside the wheel-side tube 11, a rod 4 having one end connected to the cap member 2 and the other side entering and exiting the cylinder 3, and the other end of the rod 4 A piston 5 which is connected and slidably inserted into the cylinder 3 to partition the cylinder 3 into an extension side chamber R1 on the rod 4 side and a pressure side chamber R2 on the opposite rod side; A base member 6 that divides the reservoir R3 and the pressure side chamber R2 formed between the cylinder 3 and the piston 5 to form the extension side chamber R1 and the pressure side. The first passage 5a communicating with the chamber R2 and the first passage 5a attached to the piston 5 are opened and closed, and only the flow of hydraulic oil (fluid) from the pressure side chamber R2 toward the extension side chamber R1 is allowed. The first check valve 50, the second passage 6a communicating the pressure side chamber R2 and the reservoir R3, and the second passage 6a are opened and closed, and the hydraulic fluid (fluid) from the reservoir R3 toward the pressure side chamber R2 is opened. A second check valve 60 that allows only a flow, and one end on the extension side chamber R1 side open to the side of the rod 4, and passes through the rod 4 and the cap member 2 to extend the extension side chamber R1 and the reservoir R3. And a damping force generating member V that gives resistance to the flow of hydraulic oil (fluid) that passes through the damping path MP and changes the resistance by a solenoid Sol.

  Hereinafter, in detail, the front fork F according to the present embodiment suspends a front wheel in a straddle-type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle. Since the structure of the front fork F is well known and not shown in detail, the front fork F has a pair of shock absorbers standing on both sides of the front wheel (only one shock absorber D is shown and the other shock absorber is shown). Omitted). Each of the pair of shock absorbers includes a telescopic cylinder member 1 including a vehicle body side tube 10 and a wheel side tube 11. And the vehicle body side tube 10 of both shock absorbers is connected via the vehicle body side bracket which is not shown in figure, and the wheel side bracket 12 is attached to the lower end part of the wheel side tube 11 of both shock absorbers, respectively. A vehicle body side bracket (not shown) is connected to a vehicle body frame serving as a skeleton of the vehicle body. Moreover, the wheel side bracket 12 is connected with the axle of the front wheel. For this reason, when an impact due to road surface unevenness is input to the front wheels, the wheel side tube 11 enters and exits the vehicle body side tube 10 and the front fork F expands and contracts.

  That is, in the present embodiment, the wheel side tube 11 enters and exits the vehicle body side tube 10, and the front fork F is set upside down. However, the vehicle body side tube 10 may enter and exit the wheel side tube 11 and the front fork F may be set upright. Further, the front fork F may be a cantilever type in which the front wheel is supported by only one shock absorber D. Thus, the configuration of the front fork F can be arbitrarily changed.

  In the present embodiment, the present invention is embodied in one of a pair of shock absorbers, and the configuration of the other shock absorber is arbitrary. For this reason, only one shock absorber D in which the present invention is embodied will be described in detail below.

  The shock absorber D stands on the cylindrical member 1 including the vehicle body side tube 10 and the wheel side tube 11, the cap member 2 that closes the upper opening in FIG. 1 of the cylindrical member 1, and the axial center portion of the wheel side tube 11. 1 is connected to the upper end portion in FIG. 1 and the lower side is inserted into and exits the cylinder 3, and the rod 4 is attached to the upper opening portion in FIG. An annular rod guide 7 to be supported, a piston 5 which is attached to the tip of a rod 4 inserted into the cylinder 3 and moves in the cylinder 3 in the axial direction, and a base rod fixed to the bottom of the wheel side bracket 12 8 and a base member 6 attached to the base rod 8 and fixed to the lower opening in FIG. 1 of the cylinder 3.

  A reservoir R <b> 3 is formed between the shock absorber D and the cylinder member 1 outside the cylinder 3. The reservoir R3 stores hydraulic oil (not shown). Gas is sealed above the liquid level of the hydraulic oil. In the cylindrical member 1, the upper opening in FIG. 1 is closed by the cap member 2, and the lower opening in FIG. 1 is closed by the wheel side bracket 12, and between the overlapping parts of the vehicle body side tube 10 and the wheel side tube 11. The formed cylindrical gap is closed by the seal members 13 and 14. For this reason, the hydraulic oil and gas in the reservoir R <b> 3 do not leak out of the cylindrical member 1. Further, a pair of upper and lower annular bearings 15 and 16 in FIG. 1 are provided in the cylindrical gap, and the wheel side tube 11 is slidably supported. For this reason, the wheel side tube 11 can slide smoothly in the vehicle body side tube 10.

  Further, outside the cylinder 3 of the shock absorber D, a suspension spring 21 is interposed between the cylindrical spring receiver 20 attached to the cap member 2 and the rod guide 7. The suspension spring 21 urges the shock absorber D in the extending direction and elastically supports the vehicle body. In FIG. 1, the suspension spring 21 made of a coil spring is shown, but the suspension spring 21 may be made of an air spring. Further, the suspension spring 21 may be accommodated only in one of the pair of shock absorbers constituting the front fork F.

  Subsequently, in the cylinder 3 of the shock absorber D, an extension side chamber R1 on the rod 4 side defined by the piston 5 and a pressure side chamber R2 on the piston 5 side (anti-rod side) are formed. The extension side chamber R1 and the compression side chamber R2 are filled with hydraulic oil. Further, a hole 3 a that communicates the inside and outside of the cylinder 3 is formed in the lower part of the cylinder 3 in FIG. 1. The hole 3a is designed so as not to become a throttle, and hydraulic oil in the reservoir R3 can freely flow into the cylinder 3 through the hole 3a. The base member 6 is provided above the hole 3a in FIG. 1, and partitions the pressure side chamber R2 and the reservoir R3. In the present embodiment, hydraulic fluid is used as the fluid for generating the damping force, but liquid or gas other than hydraulic fluid may be used.

  Further, an extension spring 70 is provided in the cylinder 3 between the rod guide 7 and the piston 5. For this reason, the impact at the time of the maximum extension of the front fork F can be mitigated by the extending spring 70. An annular oil lock piece 40 is provided on the outer periphery of the rod 4, and a cylindrical oil lock case 7 a into which the oil lock piece 40 is fitted when the front fork F is most compressed is provided at the upper part of the rod guide 7 in FIG. Is provided. And the oil lock member comprised including the oil lock piece 40 and the oil lock case 7a alleviates the impact of the front fork F at the time of the most compression, thereby preventing bottoming.

  Subsequently, the piston 5 that partitions the extension side chamber R1 and the pressure side chamber R2 is formed in an annular shape. The piston 5 is formed with a first passage 5a that penetrates the piston 5 in the axial direction and communicates the expansion side chamber R1 and the pressure side chamber R2. The first passage 5a is opened and closed by a first check valve 50 attached to the upper side of the piston 5 in FIG. In the compression stroke, the first check valve 50 opens the first passage 5a and allows the flow of hydraulic oil from the compression side chamber R2 toward the extension side chamber R1. On the contrary, in the extension stroke, the first check valve 50 closes the first passage 5a. That is, by the first check valve 50, the first passage 5a is set to be one-way, and only the flow of hydraulic oil from the compression side chamber R2 toward the extension side chamber R1 is allowed.

  The base member 6 that partitions the pressure side chamber R2 and the reservoir R3 is formed in an annular shape. The base member 6 is formed with a second passage 6a that penetrates the base member 6 in the axial direction and communicates the pressure side chamber R2 and the reservoir R3. The second passage 6a is opened and closed by a second check valve 60 attached to the upper side of the base member 6 in FIG. In the extension stroke, the second check valve 60 opens the second passage 6a and allows the flow of hydraulic oil from the reservoir R3 toward the pressure side chamber R2. On the contrary, in the compression stroke, the second check valve 60 closes the second passage 6a. That is, the second check valve 60 sets the second passage 6a to be one-way, and allows only the flow of hydraulic oil from the reservoir R3 to the pressure side chamber R2.

  In the present embodiment, the first check valve 50 and the second check valve 60 both have a disc valve (not shown) having a center hole that allows the rod 4 or the base rod 8 to be inserted, and the disc valve. And a spring (not shown) that urges in the closing direction. When the disc valve is lifted upward in FIG. 1, the first passage 5a or the second passage 6a can be opened largely. Further, since the disc valve has a thin annular plate shape, it does not become bulky in the axial direction even if it is attached to the piston 5 and the base member 6, and the stroke length of the front fork F is easily secured. In addition, the structure of the 1st check valve 50 and the 2nd check valve 60 can be changed arbitrarily. For example, one or both of the first check valve 50 and the second check valve 60 may be a leaf valve or a poppet valve.

  Subsequently, the rod 4 that enters and exits the cylinder 3 includes a cylindrical shaft portion 4 a that is pivotally supported by the rod guide 7 and a piston holding portion 4 b. As shown in FIG. 1, bolt portions 4a1 and 4a2 whose outer periphery is subjected to male screw processing are provided at the upper and lower portions of the shaft portion 4a in FIG. As shown in FIG. 2, the piston holding portion 4b has an annular nut portion 4b1 that is internally threaded and screwed to the outer periphery of the lower bolt portion 4a2 in FIG. An annular spacer portion 4b2 extending to the shaft portion side and having an inner diameter smaller than that of the nut portion 4b1, a bottom portion 4b3 for closing the opening on the opposite shaft portion side of the spacer portion 4b2, and a center portion of the bottom portion 4b3 from the center to the opposite shaft portion side. And an attachment portion 4b4 that extends and has an outer diameter smaller than that of the bottom portion 4b3. Male screw processing is performed on the outer periphery of the tip of the mounting portion 4b4. Then, when the mounting portion 4b4 is inserted into the center hole of the piston 5 and the nut 41 is screwed into the male threaded portion protruding from the piston 5, a step formed on the outer boundary of the mounting portion 4b4 and the bottom portion 4b3, The piston 5 can be sandwiched between and fixed.

  The spacer portion 4b2 has a hole 4b5 that penetrates the spacer portion 4b2 in the radial direction and has one end opened to the extension side chamber R1. As described above, the inner diameter of the spacer portion 4b2 is smaller than the inner diameter of the nut portion 4b1. For this reason, when the bolt part 4a2 in the shaft part 4a is screwed into the nut part 4b1, the tip of the shaft part 4a can be abutted against the step formed at the inner peripheral side boundary between the nut part 4b1 and the spacer part 4b2. Further, by doing so, it is possible to prevent the shaft 4a from closing the hole 4b5 and to guide the working oil in the extension side chamber R1 to the inside of the shaft 4a through the hole 4b5 and the spacer 4b2. it can.

  As shown in FIG. 1, a cap member 2 to which the upper end portion of the rod 4 in FIG. 1 is connected includes a case main body 2a that is screwed into the inner periphery of the upper opening in FIG. And a lid 2b attached to the upper part in FIG.

  An annular O-ring 20 that is in close contact with the inner peripheral surface of the vehicle body side tube 10 is attached to the outer periphery of the case main body 2a to prevent the hydraulic oil and gas contained in the cylindrical member 1 from flowing out. Further, the case main body 2a includes an annular nut portion 2a1 that protrudes into the vehicle body side tube 10 and is subjected to female screw processing on the inner periphery. Then, the bolt portion 4a1 on the upper side in FIG. 1 of the shaft portion 4a of the rod 4 is screwed into the inner periphery of the nut portion 2a1. Further, the case main body 2a includes a valve housing hole 2a2 that opens upward in FIG. 1, a center side through hole 2a3 that has one end opened at the bottom of the valve housing hole 2a2, and the other end opened inside the nut portion 2a1. , An outer peripheral side through hole 2a4 having one end opened at the bottom of the valve housing hole 2a2 and the other end opened at the reservoir R3 is formed. Further, an O-ring 21 is provided on the inner side of the case body 2a to prevent the hydraulic oil from flowing out of the valve housing hole 2a2.

  A lid 2b attached to the upper portion of the case body 2a in FIG. 1 is formed in a top-end cylindrical shape, and a damping force generating member V is provided in a space formed inside the valve housing hole 2a2 and the lid portion 2b. It can be accommodated. In other words, in the present embodiment, the cap member 2 serves as a case for closing the upper opening in FIG. 1 of the vehicle body side tube 10 and accommodating the damping force generating member V.

  As described above, the inner side of the shaft part 4a communicates with the inner side of the spacer part 4b2 of the piston holding part 4b and the extension side chamber R1 through the hole 4b5, the center side through hole 2a3 of the cap member 2, and the valve housing hole. 2a2 and the reservoir R3 through the outer peripheral side through hole 2a4. In other words, in the present embodiment, the attenuation passage MP that communicates the expansion side chamber R1 and the reservoir R3 includes the hole 4b5, the inner side of the spacer part 4b2, the inner side of the shaft part 4a, the central side through hole 2a3, the valve housing hole 2a2, and the outer periphery. It passes through the side through hole 2a4. Further, as described above, the lower side in FIG. 1 of the spacer portion 4b2 is closed by the bottom portion 4b3. For this reason, the attenuation passage MP does not share the pipeline with the first passage 5a, and the extension side chamber R1 is interposed between the first passage 5a and the attenuation passage MP. For this reason, the hydraulic oil in the compression side chamber R2 cannot flow into the attenuation passage MP unless it passes through the first passage 5a and the extension side chamber R1 in this order.

  A damping force generating member V is provided in the middle of the damping passage MP so that the damping force generating member V provides resistance to the flow of hydraulic oil passing through the damping passage MP and can change the resistance. It has become. The configuration of the damping force generating member V is arbitrary, but will be described below with reference to the circuit diagram of FIG. 3 showing an example of the damping force generating member V.

  The damping force generating member V is upstream of the main valve MV of the damping passage MP as a main valve MV that provides resistance to the flow of hydraulic oil that passes through the damping passage MP and a back pressure that biases the main valve MV in the closing direction. A pilot passage PP that guides the pressure of the engine to the main valve MV, a throttle O provided in the middle of the pilot passage PP, and an electromagnetic valve EV provided downstream of the throttle O of the pilot passage PP to control the back pressure; A fail passage FP that branches from the pilot passage PP downstream from the throttle O and bypasses the main valve MV, and a fail valve FV that is provided in the middle of the fail passage FP and opens at a predetermined pressure are provided.

  The pilot passage PP branches from the upstream side of the main valve MV of the attenuation passage MP and is connected to the reservoir R3. Further, a throttle O such as an orifice or a choke is provided in the middle of the pilot passage PP, and a pressure downstream from the throttle O is applied to the main valve MV as a back pressure.

  The electromagnetic valve EV includes an integrated pressure control valve PV and on-off valve SV. The pressure control valve PV is provided in the middle of the pilot passage PP. This pressure control valve PV is attached to the pressure downstream of the throttle O of the pilot passage PP and upstream of the pressure control valve PV and the spring EVs. A force acts in the valve opening direction, and a thrust by the solenoid Sol acts in the closing direction. Therefore, in this pressure control valve PV, the valve opening pressure can be changed by adjusting the thrust of the solenoid Sol. Then, by adjusting the valve opening pressure of the pressure control valve PV, the pressure downstream of the throttle O in the pilot passage PP and upstream of the pressure control valve PV can be controlled to the valve opening pressure. When the solenoid Sol is not energized, the pressure control valve PV maximizes the flow path by the spring EVs.

  On the other hand, the on-off valve SV is integrated with the pressure control valve PV, and is disposed downstream of the throttle O in the pilot passage PP and upstream of the pressure control valve PV. The on-off valve SV has a blocking position SVs for blocking the pilot passage PP and a communication position SVo for opening the pilot passage PP. The on-off valve SV is energized so as to always take the cutoff position SVs by a spring EVs shared with the pressure control valve PV, and is connected to the communication position by being pressed by the thrust of the solenoid Sol shared with the pressure control valve PV. SVo is adopted. When the solenoid Sol can be normally energized, the open / close valve SV is pressed by the thrust of the solenoid Sol to take a communication position SVo that opens the pilot passage PP. When the solenoid Sol is not energized, in the failure state where the energization is impossible or cannot be normally energized, the solenoid Sol is not supplied with current and is pushed by the spring EVs, and the on-off valve SV closes the pilot passage PP. It is like that.

  Therefore, in a state where the solenoid Sol can normally energize the solenoid Sol, the solenoid valve EV performs pressure control by the pressure control valve PV while maintaining the on-off valve SV at the communication position SVo by controlling the thrust of the solenoid Sol. Can do. In addition, since the solenoid Sol is not energized in the failure state, the pressure control valve PV opens the flow path to the maximum, but the on-off valve SV is switched to the cutoff position SVs, so that the pilot passage PP is blocked. Thus, in this embodiment, the electromagnetic valve EV is configured by integrating the pressure control valve PV and the on-off valve SV. For this reason, it is not necessary to have the solenoid Sol and the spring EVs for each of the pressure control valve PV and the on-off valve SV, and the solenoid Sol and the spring EVs can be shared. Therefore, the cost can be reduced, the weight can be reduced, and the damping force generating member V can be very miniaturized.

  The pressure downstream of the throttle O in the pilot passage PP and upstream of the on-off valve SV is guided to the main valve MV as a back pressure, and the on-off valve SV opens the pilot passage PP. Then, the pressure downstream of the throttle O in the pilot passage PP and upstream of the pressure control valve PV is nothing but the back pressure guided to the main valve MV. For this reason, at the normal time, the back pressure applied to the main valve MV can be controlled by adjusting the thrust of the solenoid Sol. And when the said back pressure is made high, the resistance by the main valve MV becomes large and the damping force which the buffer D generate | occur | produces can be enlarged. On the contrary, when the back pressure is lowered, the resistance by the main valve MV is reduced, and the damping force generated by the shock absorber D can be reduced.

  Subsequently, the fail passage FP is downstream of the throttle O of the pilot passage PP and is branched from the upstream of the on-off valve SV to the reservoir R3. A fail valve FV is provided in the middle of the fail passage FP. It has been. On this fail valve FV, the pressure downstream of the throttle O in the pilot passage PP acts in the opening direction, while the urging force by the spring FVs acts in the closing direction. That is, the fail valve FV is a relief valve that opens when the pressure upstream of the fail valve FV reaches a predetermined valve opening pressure set by the spring FVs. Therefore, even when the pilot passage PP is blocked by the on-off valve SV in the fail state, the fail valve FV exhibits a relief function. For this reason, the pressure downstream of the throttle O in the pilot passage PP and upstream of the on-off valve SV is controlled to the opening pressure of the fail valve FV. Therefore, during a failure, the back pressure guided to the main valve MV is controlled to the opening pressure of the fail valve FV, and the opening pressure of the main valve MV is also controlled to a predetermined pressure. Therefore, even during a failure, the main valve MV can provide resistance to the flow of hydraulic oil passing through the attenuation passage MP.

  Thus, in this embodiment, since the pressure control valve PV and the fail valve FV are arranged in parallel, the valve opening pressure of the fail valve FV is larger than the upper limit pressure that can be controlled by the pressure control valve PV. By doing so, a high damping force can be exhibited at the time of failure, and the vehicle body posture can be made more stable. In the present embodiment, the resistance by the main valve MV is changed by controlling the back pressure of the main valve MV with the solenoid Sol. By doing in this way, even if there is much flow volume of the hydraulic fluid which passes the main valve MV, the thrust of solenoid Sol is insufficient, and especially the malfunction that damping force adjustment becomes impossible when piston speed becomes high speed. Can be suppressed.

  Hereinafter, the operation of the front fork F according to the present embodiment will be described.

  In the extension stroke of the front fork F in which the rod 4 retracts from the cylinder 3, the first check valve 50 is closed, and the hydraulic oil in the extension side chamber R1 pressurized by the piston 5 flows into the damping passage MP from the hole 4b5 of the rod 4. Then, it passes through the main valve MV and moves to the reservoir R3. In the extension stroke of the front fork F, the second check valve 60 is opened, and the hydraulic oil in the reservoir R3 moves to the pressure side chamber R2 that expands through the second passage 6a.

  On the contrary, in the compression stroke of the front fork F in which the rod 4 enters the cylinder 3, the second check valve 60 is closed and the first check valve 50 is opened, so that the hydraulic oil in the pressure side chamber R2 pressurized by the piston 5 is first. It moves to the expansion side chamber R1 that expands through the one passage 5a. Further, in the compression stroke of the front fork F, the hydraulic oil corresponding to the rod volume that has entered the cylinder 3 flows into the damping passage MP from the hole 4b5 of the rod 4, passes through the main valve MV, and moves to the reservoir R3.

  As described above, in the present embodiment, the front fork F is set to a uniflow type, and the hydraulic oil flows through the compression side chamber R2, the extension side chamber R1, and the reservoir R3 in this order in both the expansion and compression strokes. It circulates in one direction, and hydraulic oil passes through the attenuation passage MP. For this reason, the front fork F generates a damping force due to the resistance when the hydraulic oil passes through the damping passage MP in both the expansion and compression strokes. And the said damping force can be adjusted with solenoid Sol.

  Further, in the present embodiment, the first passage 5a and the attenuation passage MP do not share a pipe line, and the extension side chamber R1 can be interposed between the first passage 5a and the attenuation passage MP. For this reason, the hydraulic oil in the pressure side chamber R2 does not flow directly into the attenuation passage MP, but always flows through the first passage 5a and the extension side chamber R1 in this order before flowing into the attenuation passage MP. Therefore, since it is possible to suppress the hydraulic oil from becoming insufficient in the extension side chamber R1 and becoming negative pressure, an appropriate damping force can be obtained.

  Further, the first passage 5a and the attenuation passage MP are in series with the expansion side chamber R1 interposed therebetween, and the flow of hydraulic oil from the expansion side chamber R1 toward the compression side chamber R2 is blocked by the first check valve 50. For this reason, even if a check valve is not provided in the attenuation passage MP, only the flow of hydraulic oil from the extension side chamber R1 to the reservoir R3 can be allowed through the attenuation passage MP, and the backflow can be prevented.

  Further, in the extension stroke of the front fork F, an amount of fluid corresponding to the reduced volume of the extension side chamber R1 passes through the damping passage MP, and in the compression stroke, an amount of fluid corresponding to the rod volume that has entered the cylinder 3 is obtained. The fluid passes through the attenuation passage MP. As described above, in the present embodiment, the flow rate of the fluid passing through the attenuation passage MP can be increased, so that the region in which the damping force can be adjusted can be widened. That is, the damping force when the piston speed is in the medium to high speed region can be adjusted.

  Further, as described above, the front fork F is set to be a uniflow type, and it is necessary to allow bidirectional flow between the extension side chamber R1 and the compression side chamber R2 and bidirectional flow between the compression side chamber R2 and the reservoir R3. The first one-way flow from the compression side chamber R2 toward the expansion side chamber R1 and the second one-way flow from the reservoir R3 toward the compression side chamber R2 may be permitted. A first passage 5 a that allows a first one-way flow is formed in the piston 5, and a first check valve 50 that realizes the one-way flow is attached to the piston 5. For this reason, the flow path area of the 1st channel | path 5a can be enlarged, and the pressure receiving area of the 1st check valve 50 can be enlarged. Therefore, it is possible to suppress the occurrence of insufficient suction during the compression stroke in which the expansion side chamber R1 is expanded. On the other hand, a second passage 6 a that allows the second one-way flow is formed in the base member 6, and a second check valve 60 that realizes the one-way flow is attached to the base member 6. For this reason, the flow passage area of the second passage 6a can be increased, and the pressure receiving area of the second check valve 60 can be increased. Therefore, it is possible to suppress the shortage of suction from occurring in the expansion stroke in which the compression side chamber R2 expands.

  Furthermore, in this embodiment, the damping force adjusting member V controls the back pressure of the main valve MV with the solenoid valve EV including the solenoid Sol to change the resistance by the main valve MV, thereby adjusting the damping force. ing. By doing in this way, compared with the case where the thrust of solenoid Sol is made to act directly on valve body MV, the thrust of solenoid Sol needs to be small, enabling miniaturization of solenoid Sol, cost reduction, and weight reduction Reduction is possible. In addition, the structure for changing the resistance by the main valve MV using solenoid Sol can be changed arbitrarily. For example, the thrust of the solenoid Sol may be directly applied to the valve body MV depending on the region where the damping force is to be adjusted, the specification of the solenoid Sol, and the like.

  Hereinafter, the function and effect of the front fork F according to the present embodiment will be described.

  In the present embodiment, the rod 4 includes a cylindrical shaft portion 4a and a piston holding portion 4b. The piston holding portion 4b has an annular nut portion 4b1 that is screwed onto the outer periphery of the shaft portion 4a, and has an inner diameter that extends from the nut portion 4b1 to the opposite shaft side and is smaller than the nut portion 4b1. An annular spacer portion 4b2 in which a hole 4b5 penetrating therethrough is formed, a bottom portion 4b3 that closes the opening on the opposite axis side of the spacer portion 4b2, and extends from the center of the bottom portion 4b3 to the opposite axis side, more than the bottom portion 4b3. And a mounting portion 4b4 having a small outer diameter. The piston 5 is formed in an annular shape and is held on the outer periphery of the mounting portion 4b4. The attenuation passage MP passes through the hole 4b5, the inner side of the spacer part 4b2, and the inner side of the shaft part 4a.

  According to the above configuration, since the inner diameter of the spacer portion 4b2 is smaller than the inner diameter of the nut portion 4b1, it is possible to prevent the hole 4b5 from being blocked by the shaft portion 4a that is screwed into the piston holding portion 4b. It is possible to easily and reliably prevent the communication between the MP and the extension side chamber R1 from being blocked. Note that the configuration of the rod 4, how to attach the piston 5, and the configuration of the damping passage MP are not limited to the above, and can be arbitrarily changed.

  In the present embodiment, the damping force generating member V includes a main valve MV that provides resistance to the flow of hydraulic oil (fluid) that passes through the damping passage MP, and a back pressure that biases the main valve MV in the closing direction. The pilot passage PP for leading the pressure upstream of the main valve MV of the damping passage MP to the main valve MV, the throttle O provided in the middle of the pilot passage PP, and the downstream of the throttle O of the pilot passage PP And a solenoid valve EV including a solenoid Sol for controlling the back pressure.

  According to the said structure, compared with the case where the thrust of solenoid Sol is made to act on the main valve MV directly, resistance by the main valve MV can be changed with a small thrust. For this reason, even if the flow rate of the hydraulic fluid that passes through the main valve MV is large, it is possible to prevent the thrust of the solenoid Sol from being insufficient. Therefore, the damping force can be adjusted even when the piston speed is in the high speed region. Moreover, the enlargement of the solenoid Sol can be suppressed and the cost and weight can be reduced. The configuration of the damping force generating member V is not limited to the above, and can be arbitrarily changed.

  Further, in the present embodiment, the front fork F includes the telescopic cylindrical member 1 including the vehicle body side tube 10 and the wheel side tube 11, the cap member 2 attached to the vehicle body side tube 10, and the wheel. A cylinder 3 provided inside the side tube 11, a rod 4 having one end connected to the cap member 2 and the other side connected to the cylinder 3, and the other end of the rod 4 are connected to the inside of the cylinder 3. Between the cylinder member 1 and the cylinder 3; and a piston 5 that is slidably inserted into the cylinder 3 and divides the inside of the cylinder 3 into an extension side chamber R1 on the rod 4 side and a pressure side chamber R2 on the opposite rod side. The base member 6 that partitions the reservoir R3 and the pressure side chamber R2, and the extension side chamber R1 and the pressure side chamber R2 that are formed in the piston 5 and communicate with each other. And a first check valve 50 that is attached to the piston 5 and opens and closes the first passage 5a to allow only the flow of hydraulic fluid (fluid) from the pressure side chamber R2 toward the extension side chamber R1. And a second passage 6a communicating the pressure side chamber R2 and the reservoir R3, and opening and closing the second passage 6a, allowing only the flow of hydraulic oil (fluid) from the reservoir R3 toward the pressure side chamber R2. The second check valve 60 and one end on the extension side chamber R1 side open to the side of the rod 4, and a damping passage that communicates the extension side chamber R1 and the reservoir R3 through the rod 4 and the cap member 2 MP and a damping force generating member V that gives resistance to the flow of hydraulic oil (fluid) passing through the damping passage MP and changes the resistance by a solenoid Sol.

  According to the above configuration, the front fork F is set to be a uniflow type, the first passage 5a and the attenuation passage MP do not share the pipeline, and the extension side chamber R2 is interposed between the first passage 5a and the attenuation passage MP. be able to. Therefore, in the compression stroke of the front fork F, the hydraulic oil in the compression side chamber R2 does not flow directly into the attenuation passage MP, but always flows through the first passage 5a and the extension side chamber R1 in this order before flowing into the attenuation passage MP. . For this reason, in the compression stroke of the front fork F, it is possible to suppress the hydraulic oil from becoming insufficient in the expansion side chamber R1 and becoming negative pressure. Therefore, an appropriate damping force can be obtained even when the front fork F is set to the uniflow type.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

EV solenoid valve F front fork MP damping passage MV main valve O throttle PP pilot passage R1 expansion side chamber R2 pressure side chamber R3 reservoir Sol solenoid V damping force generating member 1 cylinder member 2 cap member 3 cylinder 4 rod 4a shaft portion 4b piston holding portion 4b1 Nut 4b2 Spacer 4b3 Bottom 4b4 Mounting 4b5 Hole 5 Piston 5a First Passage 6 Base Member 6a Second Passage 10 Car Body Side Tube 11 Wheel Side Tube 50 First Check Valve 60 Second Check Valve

Claims (3)

A telescopic cylinder member that includes a vehicle body side tube and a wheel side tube;
A cap member attached to the vehicle body side tube;
A cylinder provided inside the wheel side tube;
A rod having one end connected to the cap member and the other side entering and exiting the cylinder;
A piston connected to the other end of the rod and slidably inserted into the cylinder to divide the cylinder into an extension side chamber on the rod side and a pressure side chamber on the opposite rod side;
A base member that partitions a reservoir formed between the cylinder member and the cylinder and the compression side chamber;
A first passage formed in the piston and communicating the extension side chamber and the pressure side chamber;
A first check valve attached to the piston for opening and closing the first passage and allowing only a flow of fluid from the pressure side chamber toward the extension side chamber;
A second passage communicating the pressure side chamber and the reservoir;
A second check valve that opens and closes the second passage and allows only a fluid flow from the reservoir toward the pressure side chamber;
One end of the extension side chamber is open to a side portion of the rod, and a damping passage that communicates the extension side chamber and the reservoir through the rod and the cap member;
A front fork comprising: a damping force generating member that gives resistance to a flow of fluid passing through the damping passage and changes the resistance by a solenoid. The damping force generating member is
A main valve that provides resistance to the flow of fluid through the damping passage;
As a back pressure for urging the main valve in the closing direction, a pilot passage for guiding the pressure upstream of the main valve of the damping passage to the main valve;
A throttle provided in the middle of the pilot passage;
The front fork according to claim 1, further comprising: an electromagnetic valve including the solenoid that is provided downstream of the throttle in the pilot passage and controls the back pressure. The rod is
A cylindrical shaft,
A piston holding part,
The piston holding part is
An annular nut portion screwed onto the outer periphery of the shaft portion;
An annular spacer portion extending from the nut portion to the opposite shaft side and having a smaller inner diameter than the nut portion, and a hole penetrating in the radial direction is formed;
A bottom portion that closes the opening on the opposite side of the spacer portion;
An attachment portion extending from the center of the bottom portion to the opposite shaft side and having an outer diameter smaller than the bottom portion;
The piston is formed in an annular shape and is held on the outer periphery of the attachment portion,
The front fork according to claim 1, wherein the damping passage passes through the hole, the inner side of the spacer portion, and the inner side of the shaft portion.

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