JP5713433B2 - Vehicle shock absorber - Google Patents

Description

  The present invention relates to an improvement of a shock absorber for a vehicle.

  Conventionally, a shock absorber for a vehicle is used by being interposed between a vehicle body and a wheel of the vehicle. For example, a cylinder, and a cylinder is slidably inserted into the cylinder, and the inside of the cylinder is extended and compressed. And a rod having one end connected to the piston and movably inserted into the cylinder.

  In such a vehicle shock absorber, a base valve is provided at the end of the cylinder to provide resistance to the flow of hydraulic oil discharged from the cylinder to the reservoir during the compression stroke, and a piston is provided at the extension stroke. A piston valve that provides resistance to the flow of hydraulic oil from the extension side chamber toward the compression side chamber is provided, and the damping force during the compression stroke and the damping force during the extension stroke are exhibited by separate damping valves.

  In particular, when the vehicle travels on the road, the wheel is pushed upward from the road surface, so that if the compression side damping force is set too high, the road surface input may be reduced. It will not be able to absorb, and a big impact (impact shock) will be applied to the car body. Therefore, according to the conventional vehicle shock absorber, the impact shock is reduced as a saturation characteristic in which the damping force reaches its peak when the piston side speed of the compression side damping force increases to some extent. If the compression side damping force is saturated as described above, the vibration damping rate during the compression stroke is reduced. Therefore, in order to compensate for this on the extension side, the extension side damping force is set high to attenuate the vibration ( For example, see Patent Document 1).

  In general, in the case of an impact shock, the frequency of vibration input to the vehicle shock absorber tends to be high, so a spool that opens and closes a bypass that bypasses the damping valve in response to high-frequency input. There is also a proposal for a vehicular shock absorber with such a vehicular shock absorber. In such a vehicular shock absorber, the damping force is reduced by opening a bypass that connects the extension side chamber and the pressure side chamber with respect to the vibration input pushing up the wheel. Impact shock is reduced (see, for example, Patent Document 2).

JP 2001-116077 A JP-A-11-94005

  However, in the vehicular shock absorber disclosed in Japanese Patent Application Laid-Open No. 2001-116077, even when the compression side damping force is set as the saturation characteristic, when an impact shock that pushes up from the road surface is input, the damping force is The impact shock can not be reduced sufficiently because it is too large, and there is room for improving the ride comfort in the vehicle.

Further, in the frequency sensitive vehicle shock absorber disclosed in Japanese Patent Laid-Open No. 11-94005, the bypass communicates with the expansion side chamber and the compression side chamber, thereby reducing the compression side damping force. together is limited, since the frequency response unit is to open and close the bypass picking up vibrations in the vehicle body side can not be opened with good response bypassed to the input of the impact shock is sufficiently reduce the impact shock And the ride comfort in the vehicle may not be improved sufficiently.

  Therefore, the present invention has been developed to improve the above-described problems, and the object of the present invention is to provide a vehicle buffer capable of effectively reducing impact shock and improving riding comfort in a vehicle. Is to provide a vessel.

To solve the problems described above, problems solving means of this invention includes a cylinder connected to the unsprung member of the vehicle, and is slidably inserted into the cylinder within the cylinder expansion side chamber and the compression side chamber a piston which divides the, a piston rod and the other end is connected to the sprung member of the vehicle with one end is inserted movably in is connected to the piston within the cylinder, a reservoir, said from the expansion side chamber An extension side damping passage that provides resistance to the flow of fluid toward the compression side chamber, a pressure side passage that allows only the flow of fluid from the compression side chamber to the extension side chamber, and a resistance to fluid flow from the compression side chamber to the reservoir and the compression side damping passage which gives, in the vehicular shock absorber and a suction passage which permits fluid flow only in a direction from said reservoir into said pressure side room, communicates only with the compression side chamber above Fluid can absorb the compliance chamber of the pressure side room, it is inserted slidably in the relaxing room provided and inertia valve which closes the compliance chamber, the inertial valve is in the valve opening direction pressure of the compression side chamber And receiving a valve body that receives an inertial force in the valve opening direction when an acceleration in the axial direction toward the piston rod acts on the cylinder, and communicates the relaxation chamber to the pressure side chamber when the valve is opened. It is characterized by. In order to solve the above-described problem, another problem-solving means of the present invention includes a cylinder connected to an unsprung member of a vehicle, and a slidably inserted into the cylinder so as to extend inside the cylinder. A piston partitioned into a pressure side chamber, a piston rod having one end connected to the piston and movably inserted into the cylinder, and the other end connected to a sprung member of the vehicle, a reservoir, and the above An extension-side damping passage that provides resistance to the flow of fluid from the extension-side chamber to the pressure-side chamber, a pressure-side passage that allows only the flow of fluid from the compression-side chamber to the extension-side chamber, and a fluid that passes from the compression-side chamber to the reservoir A shock absorber for a vehicle having a pressure-side damping passage that provides resistance to the flow of air and a suction passage that allows only a flow of fluid from the reservoir to the pressure-side chamber. A case in which the inside communicates with the pressure side chamber through a port that passes through, and a relaxation chamber that is slidably inserted into the case in a direction that coincides with the axial direction of the cylinder and communicates with the port in the case. A pressure-side damping passage, comprising: an inertia valve having a valve body that partitions; a spring element that biases the valve body; and a partition member that is provided at an end of the cylinder and partitions the pressure-side chamber and the reservoir. Has a pressure-side attenuation port that passes through the partition member and communicates the pressure-side chamber and the reservoir, and an annular leaf valve that is stacked on the reservoir side of the partition member and opens and closes the pressure-side attenuation port. A suction port through which the passage passes through the partition member to communicate the reservoir and the pressure side chamber; and an annular check valve that is stacked on the pressure side chamber side of the partition member to open and close the suction port; The leaf valve and the check valve are mounted on the outer periphery of a guide rod that penetrates the partition member, and the case is screwed onto the tip of the guide rod, whereby the partition member, the leaf valve, and the A check valve is integrated, and the valve body can shut off the port by making the sliding direction end of the valve body facing the relaxation chamber face the port, and the pressure in the pressure side chamber is increased in the valve opening direction. When the acceleration in the axial direction toward the piston rod acts on the cylinder, the inertial force in the valve opening direction is received and the relaxation chamber is expanded in the case against the urging force of the spring element. And the port is opened to allow the relaxation chamber to communicate with the pressure side chamber so that the relaxation chamber absorbs the fluid in the pressure side chamber.

  According to the vehicle shock absorber of the present invention, it is possible to reduce the compression side damping force when inputting an impact shock, while exhibiting the damping force firmly in a scene where the damping force is expected to be exerted. Can be improved.

  In addition, since the damping force reduction effect is not exerted on the extension side of the vehicle shock absorber, when the damping force is reduced in the compression stroke and the push-up input is applied, the expansion / contraction direction is switched and the vehicle shock absorber starts to extend. After the extension side damping force that is not reduced is exhibited and the impact shock is reduced, the vibrations of the sprung member and the unsprung member can be quickly converged.

It is a longitudinal section of a shock absorber for vehicles in one embodiment. It is a partially expanded longitudinal cross-sectional view of the vehicle shock absorber in one embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, a vehicle shock absorber D according to an embodiment includes a cylinder 1 and a cylinder 1 that is slidably inserted into the cylinder 1 into an extension side chamber R1 and a pressure side chamber R2. The piston 2 that is partitioned, the piston rod 3 that is connected to the piston 2 at one end and is movably inserted into the cylinder 1, the reservoir R, and the flow of fluid from the extension side chamber R1 to the pressure side chamber R2 are resisted. The expansion side damping passage 4 to be applied, the compression side passage 5 allowing only the flow of fluid from the compression side chamber R2 to the expansion side chamber R1, and the compression side attenuation to provide resistance to the flow of fluid from the compression side chamber R2 to the reservoir R. A passage 6, a suction passage 7 that allows only a flow of fluid from the reservoir R to the pressure side chamber R2, a relaxation chamber A that communicates with the pressure side chamber R2 and can absorb the fluid in the pressure side chamber R2, and Loose And an inertia valve 8 that is slidably inserted into the chamber A and closes the relaxation chamber A. The other end of the piston rod 3 is connected to a sprung member on the vehicle body side of the vehicle (not shown). In addition, the cylinder 1 is connected to the unsprung member on the wheel side of the vehicle, and is interposed between the sprung member and the unsprung member in an upright manner.

  Hereinafter, each member will be described in detail. The cylinder 1 has a cylindrical shape, in which the piston 2 is slidably inserted as described above, and the expansion side chamber R1 is located above the piston 2 in FIG. 1, and the pressure side chamber is located below in FIG. R2 is partitioned, and the extension side chamber R1 and the compression side chamber R2 are filled with, for example, hydraulic oil as a fluid. In addition, as fluid, you may fill with liquid other than hydraulic fluid, MR fluid, ER fluid, water, aqueous solution, etc.

  In addition, the cylinder 1 is accommodated in a bottomed cylindrical outer cylinder 9 disposed on the outer side, and a reservoir R is formed by an annular gap between the cylinder 1 and the outer cylinder 9. In this case, the reservoir R is filled with hydraulic oil and gas. When the fluid is hydraulic oil, the gas is preferably an inert gas such as nitrogen in order to prevent the hydraulic oil from deteriorating.

  A partition member 10 is fitted and provided at the lower end of the cylinder 1 in FIG. 1, and the compression side chamber R2 and the reservoir R are partitioned, and the upper end of the cylinder 1 in FIG. A rod guide 11 that slidably supports the piston rod 3 is fitted. The rod guide 11 is fitted to the inner periphery of the outer cylinder 9 and is crimped to the upper end of the outer cylinder 9 so that the rod guide 11 is stacked above the rod guide 11 in FIG. These are fixed to the outer cylinder 9 together with a seal member 12 that seals between the two. When the rod guide 11 is fixed to the outer cylinder 9 in this way, the cylinder 1 is sandwiched between the partition member 10 placed on the bottom of the outer cylinder 9 and the rod guide 11, and the cylinder 1 is also attached to the outer cylinder 9 together with the partition member 10. Fixed. Instead of caulking the upper end opening end of the outer cylinder 9, a cap is screwed into the upper end opening, and the sealing member 12, the rod guide 11, and the cylinder 1 are connected with the cap and the bottom of the outer cylinder 9. Alternatively, the partition member 10 may be sandwiched so that these members are integrated with the outer cylinder 9.

  The piston 2 is fixed to the lower end in FIG. 1 which is one end of the piston rod 3, and the piston 2 is provided with an extension-side damping passage 4 and a pressure-side passage 5. The expansion-side damping passage 4 includes a passage 4a that connects the expansion-side chamber R1 and the compression-side chamber R2, and a damping valve 4b that is provided in the middle of the passage 4a. The damping valve 4b moves from the expansion-side chamber R1 to the compression-side chamber R2. Only the flow of the working oil is allowed and resistance is given to the flow, and the extension side attenuation passage 4 is set as a one-way attenuation passage.

  The pressure side passage 5 includes a passage 5a communicating the pressure side chamber R2 and the extension side chamber R1, and a check valve 5b provided in the middle of the passage 5a. The check valve 5b is directed from the pressure side chamber R2 to the extension side chamber R1. Only the flow of hydraulic oil is allowed, and the pressure side passage 5 is set as a one-way passage.

  The partition member 10 includes a small-diameter small-diameter portion 10a fitted to the lower end of the cylinder 1, a cylindrical skirt 10b provided on the outer periphery of the lower end, a notch 10c provided on the skirt 10b and communicating between the inside and the outside of the skirt 10b, and a pressure side chamber. The pressure side damping port 10d and the suction port 10e leading from the pressure side chamber end facing the R2 to the pressure side chamber end facing the skirt 10b from the pressure side chamber end at the upper end in FIG. 2, and the penetrating through the shaft portion from the pressure side chamber end to the pressure side chamber end And a hole 10f. In the case of this embodiment, a plurality of compression side attenuation ports 10d are provided on the same circumference of the partition member 10, and the suction port 10e is similarly formed from a circle in which the compression side attenuation port 10d is provided on the partition member 10. A plurality of ports are provided on the circumference of a large-diameter circle, but the number of these ports can be set arbitrarily and may be singular.

  The partition member 10 is sandwiched between the outer cylinder 9 and the cylinder 1 by fitting the small-diameter portion 10a to the end of the cylinder 1 and bringing the lower end of the skirt 10b into contact with the bottom of the outer cylinder 9. 9 and the partition member 10 partitions the pressure side chamber R2 and the reservoir R from each other. Further, the compression side damping port 10d and the suction port 10e both have an upper end opening end facing the compression side chamber R2, and a lower end opening end leading to the reservoir R through a notch 10c provided in the skirt 10b. The pressure side attenuation port 10d and the suction port 10e communicate the pressure side chamber R2 and the reservoir R.

  Further, an annular check valve 13 is stacked at the upper end in FIG. 2 that is the pressure side chamber side end of the partition member 10, and the lower end in FIG. 2 that is the counter pressure side chamber side end of the partition member 10 is annular The leaf valves 14 are stacked, and are attached to the outer periphery of the guide rod 15 inserted into the through hole 10 f of the partition member 10 together with the partition member 10, and are fixed by the case 16 that forms the relaxation chamber A.

  Specifically, the guide rod 15 includes a shaft portion 15a inserted into the through hole 10f, a flange 15b provided on the outer periphery of the lower end in FIG. 2 of the shaft portion 15a, and a hollow portion that vertically penetrates the shaft portion 15a. 15c and a screw portion 15d provided on the outer periphery of the upper end in FIG. 2 of the shaft portion 15a. When the case 16 is screwed to the screw portion 15d, the flange 15b and the case 16 The check valve 13, the partition member 10 and the leaf valve 14 are sandwiched and integrated with each other.

  As described above, the check valve 13 is fixed on the inner peripheral side by the guide rod 15 and allowed to bend on the outer peripheral side, and opens and closes the opening on the pressure side chamber side of the suction port 10e. The check valve 13 and the suction port 10e form a suction passage 7. The check valve 13 allows only the flow of hydraulic oil from the reservoir R to the pressure side chamber R2, and the suction passage 7 is connected from the reservoir R to the pressure side chamber. It is set as a one-way passage that allows only the flow of hydraulic oil toward R2. The check valve 13 includes a through hole 13a so that the opening end on the pressure side chamber side of the pressure side attenuation port 10d is not blocked.

  Further, in this case, the leaf valve 14 is configured by stacking a plurality of annular plates, the inner peripheral side is fixed by the guide rod 15 and the outer peripheral side is allowed to be bent, and the counter pressure side chamber of the compression side damping port 0d described above is allowed. The opening on the side is opened and closed. The leaf valve 14 and the pressure side damping port 10d form a pressure side damping passage 6. The leaf valve 14 allows only the flow of hydraulic oil from the pressure side chamber R2 to the reservoir R and gives resistance to the flow. The damping passage 6 is set as a one-way damping passage that allows only the flow of hydraulic oil from the pressure side chamber R2 to the reservoir R. In this case, the outer diameter of the leaf valve 14 is set to an outer diameter that does not block the suction port 10e, and does not affect the suction port 10e.

  The shape and structure of the partition member 10 are not limited to those described above, and can be appropriately changed in design. The compression side damping passage 6 and the suction passage 7 may be provided not in the partition member 10 but in other places. Is possible.

As described above, the vehicle shock absorber D is a single rod shock absorber. Basically, during the extension stroke, the piston 2 moves upward in FIG. R1 is compressed and hydraulic oil moves from the expansion side chamber R1 to the compression side chamber R2 via the expansion side attenuation passage 4, and the expansion side attenuation passage 4 provides resistance to the flow of hydraulic oil, so that the expansion side chamber R1 and the compression side chamber A difference is generated in the pressure of R2, and a damping force that suppresses the extension operation is generated according to the differential pressure. Further, during this extension stroke, a sufficient amount of hydraulic oil for the piston rod 3 to retreat from the cylinder 1 is insufficient in the cylinder 1, but this insufficient hydraulic oil is supplied from the reservoir R through the suction passage 7 to the pressure side chamber R <b> 2. Compensated by inhaling. On the other hand, during the compression stroke, the piston 2 moves downward in FIG. 1 with respect to the cylinder 1, and the compression side chamber R2 contracts and the expansion side chamber R1 expands, so that hydraulic oil flows from the compression side chamber R2 to the expansion side chamber R1. When the piston rod 3 moves through the pressure side passage 5 and enters the cylinder 1, excess hydraulic oil in the cylinder 1 is discharged to the reservoir R through the pressure side attenuation passage 6. In this case, increased compression side damping passage 6 the pressure in the Runode cylinder 1 gives the resistance to the flow of the working oil, generating a damping force for restricting the compressed working in accordance with the pressure increase.

  Next, the relaxation chamber A and the inertia valve 8 will be described. The basic operation of the vehicular shock absorber D is as described above. In the vehicular shock absorber D, the relaxation that is communicated with the pressure side chamber R2 and can absorb the hydraulic oil as the fluid in the pressure side chamber R2. A chamber A and an inertia valve 8 that is slidably inserted into the relaxation chamber A and closes the relaxation chamber A. The inertia valve 8 receives the pressure of the pressure side chamber R2 in the valve opening direction. In addition, the cylinder 1 is provided with a valve body 20 that receives an inertial force in the valve opening direction when an acceleration in the axial direction toward the piston rod 3 is applied to the cylinder 1, and when the valve is opened, the relaxation chamber A is defined as the pressure side chamber R2. It has come to communicate with. When the cylinder 1 has a push-up input such that the wheel rides on the road surface projection, the valve body 20 is moved in the valve opening direction, and the inertia valve 8 is opened, and the relaxation chamber A is moved to the pressure side chamber R2. It communicates and absorbs hydraulic fluid from pressure side room R2.

The acceleration when the inertia valve 8 is opened is set to such a magnitude that it acts when riding on the projection on the road surface while the vehicle is running, if the pressure in the compression side chamber R2 is ignored. Is set to, for example, about 98 m / s ² (10 G (gravitational acceleration)), and when an acceleration higher than this acceleration acts on the cylinder 1, the inertia valve 8 is opened and the relaxation chamber A becomes the compression side chamber R 2. It is supposed to lead to. Further, even when the acceleration acting on the cylinder 1 does not reach the above value, the valve body 20 is pressed in the valve opening direction by the action of the pressure in the pressure side chamber R2, and the pressure of the pressure side chamber R2 is subsidized. Therefore, when the vehicle shock absorber D is in the compression stroke and the pressure in the compression side chamber R2 is high, the valve body 20 opens without reaching the acceleration. On the other hand, when the acceleration acting on the cylinder 1 is small and the valve body 20 does not move in the valve opening direction even when the pressure of the pressure side chamber R2 is subsidized, the relaxation chamber A is closed by the inertia valve 8 and the pressure side chamber R2 is closed. Communication is cut off. The value of acceleration at which the valve body 20 opens regardless of the pressure in the pressure side chamber R2 is not limited to the above, but is the value of acceleration acting on the cylinder 1 when an impact shock is input. It only has to be set.

  In this way, when the inertial valve 8 is opened when the vehicle shock absorber D is in the compression stroke, the intrusion volume of the piston rod 3 in the cylinder 1 is communicated with the compression side chamber R2. However, a part or all of the excess hydraulic oil is absorbed in the relaxation chamber A, the flow rate of the hydraulic oil passing through the compression side damping passage 6 is reduced, and the compression side damping force is reduced. be able to. The inertia valve 8 is opened when a large acceleration in the direction toward the piston rod 3 is applied to the cylinder 1 connected to the unsprung member of the vehicle. When a large acceleration is applied to the cylinder 1 by climbing onto the cylinder 1 or the like, the inertia valve 8 is opened to reduce the compression-side damping force and to apply a push-up input to suppress the transmission of shocking vibrations to the vehicle body. That is, impact shock can be reduced. Such shock acceleration is transmitted to the cylinder 1 when input to the unsprung member, and further to the piston rod 3 via the hydraulic oil. Since the acceleration is not immediately transmitted to the piston rod 3 by the suspension spring, the structure that picks up the acceleration acting on the piston rod 3 to reduce the damping force takes a long time to reduce the damping force and sufficiently absorbs the impact shock. Although it cannot be reduced, the inertia valve 8 is opened by the acceleration acting on the cylinder 1 connected to the unsprung member as described above. Therefore, the effect of reducing the damping force is expressed without delaying the input of the impact shock. Can be sufficiently reduced.

  On the other hand, when the vehicle turns or travels on a good road, the large acceleration does not act on the cylinder 1 and the inertia valve 8 does not open, so that the relaxation chamber A is not communicated with the compression chamber R2. In this case, the vehicle shock absorber D causes the total flow rate of the hydraulic fluid from the cylinder 1 to the reservoir R to flow through the compression side damping passage 6 as described in the above basic operation without reducing the compression side damping force. By passing through and generating a compression side damping force, the vehicle body roll can be suppressed and the vehicle body posture can be stabilized during turning.

  Further, when the inertial valve 8 is opened when the vehicle shock absorber D is in the extension stroke, when the relaxation chamber A communicates with the compression side chamber R2, the extension side damping passage 4 is extended from the extension side chamber R1 compressed by the piston 2. The hydraulic oil moves to the compression side chamber R2 through the pressure side, and the extension side damping passage 4 gives resistance to the flow of the hydraulic oil and exhibits the extension side damping force. That is, in the extension stroke, even if the relaxation chamber A communicates with the compression side chamber R2, the vehicle shock absorber D exhibits the extension side damping force without being affected by this, so that the damping force is reduced. Is not done. The same applies even if the relaxation chamber A is blocked from the compression side chamber R2. Thus, the relaxation chamber A does not affect the extension side damping force of the vehicle shock absorber D.

  Therefore, according to the vehicle shock absorber D, the damping force is exerted firmly in a scene where the damping force is expected to be exhibited, but the compression side damping force is reduced when the impact shock is input to improve the riding comfort in the vehicle. It can be done.

  The valve body 20 in the inertial valve 8 can be opened only by the inertial force due to the acceleration acting on the cylinder 1, but is opened not only with the inertial force but also with the assistance of the pressure in the pressure side chamber R2. Since the valve is designed to open, the valve body 20 can be opened, and the inertial valve 8 can be reliably opened to reduce the impact shock.

  In addition, since the damping force reducing effect is not exhibited on the extension side of the vehicle shock absorber D, after the damping force is reduced in the compression stroke and the push-up input is applied, the expansion / contraction direction is switched and the vehicle shock absorber D starts to extend. In this case, after the extension side damping force that is not reduced is exhibited and the impact shock is reduced, the vibrations of the sprung member and the unsprung member can be quickly converged.

  Further, the specific structures of the relaxation chamber A and the inertia valve 8 will be described. The relaxation chamber A is formed by a hollow case 16 that is screwed into a screw portion 15d provided at the upper end in FIG. 2 of the guide rod 15, and the inertia valve 8 is disposed in the case 16 in the axial direction of the cylinder 1. The valve body 20 is slidably inserted in a direction that coincides with the valve body 20, and a spring element 21 that biases the valve body 20.

  The case 16 includes a top cylindrical case body 17 and a nut portion 18 which is screwed to the opening end of the case body 17 and is screwed to a screw portion 15d provided at the upper end of the guide rod 15 in FIG. The case 16 communicates with the inside and outside of the case 16 through a port 19 provided at the top of the case body 17. Further, in the case of this embodiment, the case 16 is disposed in the pressure side chamber R2, and by providing the port 19, the inside of the case 16 is communicated with the pressure side chamber R2. In addition, when integrating the case main body 17 and the nut part 18, these may be welded, the nut part 18 may be press-fitted into the case main body 17, and these may be integrated, or other means may be used. .

  Further, a valve body 20 of the inertia valve 8 is slidably inserted in the case main body 17, and the valve body 20 is provided in the back pressure chamber B serving as a relaxation chamber A and an anti-relaxation chamber side in the case 16. It is divided into and. In this case, the valve body 20 includes a top portion 20a and a cylindrical portion 20b suspended from the outer periphery of the top portion 20a in FIG. A projection 20d is provided at the lower end of the top portion 20a.

A spring element 21 formed of a coil spring is interposed between the valve body 20 and the nut portion 18 of the case 16 in a compressed state. The valve body 20 is biased by the spring element 21. In the no-load state, the convex portion 20 c is positioned at the uppermost position in contact with the top portion of the case body 17. The protrusion 20d has a function of positioning the spring element 21 in the radial direction, and when the valve body 20 moves downward in FIG. 2 against the urging force of the spring element 21 in the case 16, FIG. The communication between the hollow portion 15c and the back pressure chamber B is gradually interrupted by approaching the tip that is the middle upper end, and the valve body 20 moves to the point just before the projection 20d contacts the upper end of the rod guide 15. Then, the protrusion 20d and the upper end of the guide rod 15 function as a throttle valve, and the movement of the valve body 20 to the lowermost position is further suppressed, so that the protrusion 20d of the valve body 20 contacts the guide rod 15. However, the sound generated at the time of contact can be reduced.

  Further, in the state where the valve body 20 is positioned at the uppermost position, the port 19 is closed with the upper end in FIG. 2 of the convex portion 20c which is the sliding direction end on the relaxation chamber A side facing, The pressure in the pressure side chamber R <b> 2 is pressed through the port 19 in the direction in which the valve body 20 is opened, that is, the valve body 20 is pressed toward the back pressure chamber B in the case 16. Since the port 19 is closed with the valve body 20 as described above, it is possible to adjust the force of pressing the valve body 20 in the direction of opening the valve body 20 by the pressure in the pressure side chamber R2 with the pressure receiving area inside the convex portion 20c.

  When the valve body 20 moves from the uppermost position in the case 16 in the direction of enlarging the relaxation chamber A, which is the lower side in FIG. 2, the relaxation chamber A communicates with the compression side chamber R2. When the valve body 20 opens the port 19, the pressure in the pressure side chamber R2 propagates into the relaxation chamber A. After the valve is opened, the valve body 20 has the pressure in the pressure side chamber R2 with the entire upper surface in FIG. It is greatly pushed down to receive. Thus, since the valve body 20 is largely pushed down not only by the inertia force but also by the pressure of the pressure side chamber R2 after the valve is opened, the valve closing of the inertia valve 8 is delayed against the urging force of the spring element 21. The damping force reduction effect is considered not to disappear in a state where the impact shock is not sufficiently reduced.

  The spring element 21 is interposed between the valve body 20 and the nut portion 18 in a compressed state, that is, in a state where an initial load is applied, but the initial load applied to the spring element 21 is Is determined by the relationship with the inertial force that acts on the valve body 20 when the predetermined acceleration acts on the cylinder 1. That is, when the inertial force is applied to the valve body 20, the spring element 21 is pressed and contracted to open the port 19 to open the valve 19. Therefore, the initial load is set when the valve body 20 is opened. It is determined from the relationship between the moving distance and the spring constant. Further, how much the valve body 20 moves from the uppermost position with respect to the case 16 is optimal for a vehicle to which the vehicle shock absorber 1 is applied together with the spring constant of the spring element 21 and the initial load. This moving distance may be determined empirically or experimentally.

  The mass of the valve body 20 and the spring constant of the spring element 21 are set so that the resonance frequency of the system of the valve body 20 and the spring element 21 does not match the resonance frequency of the unsprung member. Since the unsprung member resonates when it vibrates at the unsprung resonance frequency, the vehicle shock absorber D preferably exhibits a damping force against such vibration to suppress the resonance. When the resonance frequency of the system 20 and the spring element 21 matches the resonance frequency of the unsprung member, the valve body 20 also resonates and opens, and the relaxation chamber A communicates with the compression side chamber R2 to reduce the damping force. Since the effect may be exerted and the resonance cannot be effectively suppressed, as described above, the resonance frequency of the system of the valve body 20 and the spring element 21 is set so as not to coincide with the resonance frequency of the unsprung member. By doing so, resonance and fluttering of the unsprung member can be effectively suppressed while enjoying the effect of reducing the impact shock.

  In the inertia valve 8 and the relaxation chamber A specifically configured as described above, the sliding direction of the valve body 20 coincides with the axial direction of the cylinder 1, and the case 16 is interposed via the partition member 10 and the guide rod 15. 2, acceleration in the direction of the axial direction toward the piston rod 3 acts on the cylinder 1, and the spring element 21 is compressed and contracted in the case 16 within the case 16, and lower in FIG. 2. When an inertial force that moves backward is applied, or when pressure in the pressure side chamber R2 that moves the valve body 20 backwards acts in addition to the inertial force, the inertial valve 8 is opened and the port 19 is opened. Therefore, the relaxation chamber A can be communicated with the pressure side chamber R2 to absorb the hydraulic oil from the pressure side chamber R2. Accordingly, as described above, when the vehicle shock absorber D is in the compression stroke, if an acceleration equal to or higher than a predetermined acceleration in the upward direction in FIG. However, the inertial force 8 moves in the case 16 and the inertial valve 8 is opened to reduce the compression side damping force, thereby reducing the impact shock. In addition, since this reduction in damping force does not appear in the expansion stroke of the vehicle shock absorber D, after the damping force is reduced in the compression stroke and the push-up input is applied, the expansion / contraction direction is switched and the vehicle shock absorber D begins to expand. In this case, after the extension side damping force that is not reduced is exhibited and the impact shock is reduced, the vibrations of the sprung member and the unsprung member can be quickly converged.

  Therefore, it is possible to improve the riding comfort in the vehicle by reducing the compression side damping force when inputting the impact shock while exhibiting the damping force firmly in a scene where the damping force is expected to be exhibited. Further, the valve body 20 in the inertia valve 8 can be opened only by the inertia force due to the acceleration acting on the cylinder 1, but is opened not only by the inertia force but also by the assistance of the pressure in the compression side chamber R2. Since the valve is designed to open, the valve body 20 can be opened, and the inertial valve 8 can be reliably opened to reduce the impact shock.

  In this embodiment, the back pressure chamber B is communicated with the reservoir R through the hollow portion 15c of the guide rod 15 and is not a closed space. Therefore, the valve body 20 is prevented from being opened and closed. Therefore, the onset and cancellation of the damping force reduction effect will not be slow, and only the impact shock can be effectively reduced. In addition, after providing a through-hole penetrating the top portion 20a of the valve body 20 and communicating the relaxation chamber A to the compression side chamber R2, the compression side chamber R2 communicates with the reservoir R via the relaxation chamber A and the back pressure chamber B. Thus, the hydraulic oil in the cylinder 1 can be released to the reservoir R.

  A throttle valve is provided in the middle of the passage communicating the back pressure chamber B with the reservoir R, for example, in the middle of the hollow portion 15c of the guide rod 15, and for example, the vibration of the valve body 20 exceeds the unsprung resonance frequency. Then, the movement of the valve body 20 may be suppressed, the damping force reduction effect may be attenuated, and the flutter of the unsprung member may be suppressed.

  Further, although the relaxation chamber A communicates with the compression side chamber R2, the impact pressure can be reduced as described above without the back pressure chamber B communicating with the reservoir R. Therefore, the back pressure chamber B is closed. Or may be open to the atmosphere. The spring element 21 may be formed of an elastic body other than the coil spring described above. When the back pressure chamber B is a closed space as described above, the spring element 21 is formed of a gas spring. You can also.

  Further, in this embodiment, the case 16 forming the relaxation chamber A is accommodated in the compression side chamber R2, but it is connected to the cylinder 1 so that the acceleration of the unsprung member acting on the cylinder 1 is transmitted. Therefore, it can be installed on the side of the cylinder 1 or on the outside of the outer cylinder 9. However, as described above, by making the case 16 function as a nut for fixing the check valve 13 and the leaf valve 14 to the partition member 10, it is possible to reduce the number of parts and avoid the increase in the size of the vehicle shock absorber D. .

  In this embodiment, the pressure-side damping passage 6 is a leaf valve 14, but it goes without saying that other valve elements may be used.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

  The vehicular shock absorber of the present invention can be used for vibration control of a vehicle.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Piston rod 4 Extension side damping passage 4a, 5a passage 4b Damping valve 5 Pressure side passage 5b Check valve 6 Pressure side damping passage 7 Suction passage 8 Inertia valve 9 Outer cylinder 10 Partition member 11 Rod guide 12 Seal member 10a Small diameter part 10b Skirt 10c Notch 10d Pressure side damping port 10e Suction port 10f Through hole 13 Check valve 13a Through hole 14 Leaf valve 15 Guide rod 15a Shaft portion 15b Flange 15c Hollow portion 15d Screw portion 16 Case 17 Case body 18 Nut portion 19 Port 20 Valve body 20a Top portion 20b Tube portion 20c Projection portion 20d Protrusion 21 Spring element A Relaxation chamber B Back pressure chamber D Vehicle shock absorber R Reservoir R1 Extension side chamber R2 Pressure side chamber

Claims (6)

A cylinder connected to the unsprung member of a vehicle, a piston for partitioning the inside the cylinder in the expansion side chamber and the compression side chamber is slidably inserted into said cylinder, one end connected to the piston within the cylinder A piston rod whose other end is connected to the sprung member of the vehicle, a reservoir, an extension-side damping passage that provides resistance to the flow of fluid from the extension-side chamber to the compression-side chamber, A pressure side passage that allows only the flow of fluid from the pressure side chamber to the extension side chamber, a pressure side attenuation passage that provides resistance to the flow of fluid from the pressure side chamber to the reservoir, and a fluid that flows from the reservoir to the pressure side chamber. In a vehicle shock absorber with a suction passage that allows only flow,
And capable of absorbing buffering chamber the pressure side room of the fluid is communicated only to the compression side chamber,
Are slidably inserted in the relaxing room provided and inertia valve which closes the relaxation chamber,
Said inertia valve, as well as receives the pressure of the compression side chamber in the valve opening direction, a valve body which receives the inertial force in the valve opening direction when the direction of the acceleration towards the piston rod side a axial to the cylinder acts The vehicle shock absorber is characterized in that the relaxation chamber communicates with the pressure side chamber when the valve is opened. A hollow case is provided in which the inside communicates with the pressure side chamber through a port communicating inside and outside.
Said inertia valve, and the valve body for partitioning the relaxation chamber is slidably inserted in a direction matching the axial direction of the cylinder within the casing communicates with said port in said casing, said valve body A spring element for biasing
The valve body, the sliding direction end facing the compliance chamber of the valve body as well as blocking the ports be facing the port, the relaxing of the said casing against the biasing force of the spring element The vehicle shock absorber according to claim 1, wherein the port is opened by moving the chamber in an expanding direction. The vehicular shock absorber according to claim 2, wherein the valve body defines a back pressure chamber communicating with the reservoir inside the case and on the opposite side of the relaxation chamber. A cylinder connected to an unsprung member of the vehicle; a piston which is slidably inserted into the cylinder and divides the cylinder into an extension side chamber and a pressure side chamber; and one end connected to the piston and connected to the piston A piston rod whose other end is connected to the sprung member of the vehicle, a reservoir, an extension-side damping passage that provides resistance to the flow of fluid from the extension-side chamber to the compression-side chamber, A pressure side passage that allows only the flow of fluid from the pressure side chamber to the extension side chamber, a pressure side attenuation passage that provides resistance to the flow of fluid from the pressure side chamber to the reservoir, and a fluid that flows from the reservoir to the pressure side chamber. In a vehicle shock absorber with a suction passage that allows only flow,
A case that is hollow and communicates with the pressure side chamber through a port communicating inside and outside;
A valve body that is slidably inserted into the case in a direction that coincides with the axial direction of the cylinder and that defines a relaxation chamber that communicates with the port in the case; and a spring element that biases the valve body; An inertial valve having
A partition member provided at an end of the cylinder and partitioning the pressure side chamber and the reservoir ;
The compression side damping passage is laminated to reservoir side of the compression side damping port and the partition member for communication between the compression side chamber and the reservoir through said partition member have the annular leaf valve for opening and closing the compression side damping ports And
The suction passage is stacked on the pressure side chamber side of the suction port and the partition member for communication between the reservoir and the pressure side chamber through said partition member and an annular check valve for opening and closing the suction port,
And the leaf valve and the check valve is mounted on the outer periphery of the guide rod penetrating the partition member, the case that is screwed to the distal end of the guide rod, the partition member, the leaf valve and the check valve Integrated ,
The valve body is
The port can be shut off by facing the port in the sliding direction facing the relaxation chamber of the valve body,
When pressure in the pressure side chamber is received in the valve opening direction and acceleration in the axial direction toward the piston rod acts on the cylinder, it receives inertial force in the valve opening direction and resists the biasing force of the spring element. And moving the inside of the case in the direction of enlarging the relaxation chamber, opening the port, communicating the relaxation chamber with the pressure side chamber, and allowing the relaxation chamber to absorb the fluid in the pressure side chamber. Vehicle shock absorber. The valve body defines a back pressure chamber in the case and on the opposite side of the relaxation chamber,
The guide lot has a hollow part,
The vehicular shock absorber according to claim 4, wherein the back pressure chamber communicates with the reservoir through a hollow portion of the guide rod. 6. The vehicle shock absorber according to claim 2, wherein a resonance frequency of a system of the valve body and the spring element is not matched with a resonance frequency of the unsprung member.

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