Abstract: A free piston defines a gas chamber in a cylinder, an interior of which is divided into a rod-side chamber and a bottom-side chamber by a piston. An accumulator having a gas chamber is connected to the rod-side chamber by a first oil line, midway of which is provided a damping-force generating unit. Also, the bottom-side chamber and the first oil line are communicated to each other by a communication line, midway of which is provided a spring-constant switchover valve for communication and shut-off of the communication line. Accordingly, when the spring-constant switchover valve puts the communication line in communication, the two gas chambers are compressed to make a spring constant small, thereby making comfort in a vehicle favorable. Meanwhile, the spring-constant switchover valve shuts off the communication line, only one of the gas chambers is compressed to make the spring constant large, thereby limiting a contracting displacement of a piston rod and suppressing rolling of the vehicle.

Abstract: A damping force control type hydraulic shock absorber capable of generating stable damping force even if the flow rate of hydraulic fluid changes sharply. Hydraulic fluid chambers at the respective ends of valve members are cut off from the downstream ports of extension and compression pressure control valves by flange portions of the valve members. When the flow rate of hydraulic fluid increases sharply, even if the pressure in the downstream ports changes sharply owing to the flow resistance in check valves on the downstream side of the downstream ports, the pressure is not transmitted to the hydraulic fluid chambers. Therefore, there is no possibility of the slider moving under the influence of such a pressure change.

Abstract: The flow of a hydraulic fluid, which occurs under a sliding movement of a piston in a cylinder, is directly controlled by virtue of an extension-stroke pressure control valve and a compression-stroke pressure control valve. At the same time, the pressure in a back pressure chamber is varied, to thereby adjust the valve opening pressure for a main disk valve. This enables control of a damping force over a wide range. In each of the extension-stroke and compression-stroke pressure control valves, a thrust is generated in a slider due to a difference in pressure-receiving areas between a stepped portion of the slider and a sub disk valve in a valve chamber. The valve opening pressure is controlled, according to the balance between the thrust of the slider and a thrust of a proportional solenoid. By reducing the difference in the pressure-receiving areas in the valve chamber, the load applied to the proportional solenoid can be reduced.

Abstract: A pilot chamber is formed at the back of a disk valve for each of the fluid flow systems for the extension and compression strokes. Damping force in a low piston speed region is controlled with a pressure control valve. The valve opening pressure of the disk valve is controlled by varying a pilot pressure introduced into the pilot chamber from a cylinder's hydraulic fluid chamber through a cut portion in a piston bolt and an orifice groove formed in a fixed member supporting the disk valve, thereby controlling damping force in a high piston speed region. A sharp pressure change occurring when the stroke direction of a piston rod changes is attenuated by the restricting action of the orifice groove so as not to be readily transmittable to the pilot chamber. Accordingly, it is possible to suppress a change in damping force due to the sharp pressure change and hence possible to obtain stable damping force.

Abstract: The pilot suspension apparatus of the present invention is capable of biasing a damping valve in a direction for closing the valve, due to application of a pilot pressure. The suspension apparatus comprises at least one pair of hydraulic shock absorbers which are capable of controlling a damping force and which are connected by a connecting pipe. The at least one pair of hydraulic shock absorbers are provided at front and rear wheels or left and right wheels on the same side of a vehicle or are provided in a diagonally shaped relationship. A control valve is provided so as to control the pilot pressure. The control valve is adapted to be controlled by application of a differential pressure which is generated between respective cylinders of the at least one pair of shock absorbers.

Abstract: A damping force control type hydraulic shock absorber includes a plunger having a small-diameter main body portion slidably guided by a first fixed core made of a magnetic material. The plunger has a large-diameter attracted portion at an end thereof closer to a second fixed core. The diameter (D2) of the attracted portion is set larger than the diameter (D1) of the main body portion (D2>D1), thereby increasing the area of the mutually opposing surfaces of the attracted portion and the second fixed core. Accordingly, attraction force acting on the attracted portion can be increased without reducing the magnetic flux density at the main body portion.

Abstract: The flow of a hydraulic fluid caused by sliding movement of a piston in a cylinder is controlled by a disk valve and extension- and contraction-side main valves, thereby generating damping force. By controlling the valve opening pressures of the disk valve as a pressure control valve with respect to extension- and compression-side valve seats with a proportional solenoid actuator, damping force can be directly controlled independently of the piston speed. Moreover, the pressures in pilot chambers are changed to control the valve opening pressures of the extension- and compression-side main valves. Because the disk valve is placed between the extension- and compression-side valve seats, it is possible to simultaneously select different damping force characteristics for the extension and compression sides.

Abstract: A damping force control type hydraulic shock absorber capable of generating stable damping force even if the flow rate of hydraulic fluid changes sharply. A slider is slidably fitted in a piston bolt. Valve members are secured to both ends of the slider to form extension and compression pressure control valves for controlling the pressure of hydraulic fluid between upstream and downstream ports provided in the piston bolt. Hydraulic fluid chambers at the respective ends of the valve members are cut off from the downstream ports of the extension and compression pressure control valves by flange portions of the valve members. When the flow rate of hydraulic fluid increases sharply, even if the pressure in the downstream ports changes sharply owing to the flow resistance in check valves on the downstream side of the downstream ports, the pressure is not transmitted to the hydraulic fluid chambers. Therefore, there is no possibility of the slider moving under the influence of such a pressure change.

Abstract: In a disclosed solenoid apparatus, one end of an actuating rod secured to the plunger of the solenoid apparatus abuts on a slider equipped with extension and compression pressure control valves. A coil is excited to induce thrust in the plunger, thereby moving the slider to control damping force. An end of the actuating rod projects from the plunger and extends through a rod guide to form a hydraulic fluid chamber at the rear of the plunger. Hydraulic fluid chambers inside the hydraulic shock absorber are communicated directly with the hydraulic fluid chamber at the rear of the plunger through hydraulic fluid passages in the actuating rod. Even when there is a sharp change in the pressure in the hydraulic fluid chambers inside the hydraulic shock absorber, the pressures acting on both ends of the plunger are kept equal to each other at all times.

Abstract: A hydraulic shock absorber of a damping force adjustable type generates a damping force by controlling the flow of an oily fluid caused to occur by the slidable movement of the piston in the cylinder by means of a subsidiary disc valve, a main disc valve and a disc valve mounted on the plunger. The damping force is controlled directly regardless of the piston speed by controlling the relief pressure of the disc valve in accordance with an electric current applied to a coil. The pressure in a back pressure chamber is varied with the relief pressure of the disc valve and the pressure for opening the main disc valve is controlled, thereby extending the scope of controlling the damping force. Further, an excessive rise in the damping force can be controlled due to a rapid input, and an impact can be absorbed by allowing the disc valve to bend and relieving oily fluid in the back pressure chamber.

Abstract: A damping force control type hydraulic shock absorber is provided having a broad damping force control range and is capable of obtaining appropriate damping force over the entire piston speed range from a low speed region to a high speed region. A piston is fitted in a cylinder, and a reservoir is connected to the cylinder. A cylinder upper chamber and the reservoir are communicated through a main passage in which a main damping valve is provided. The cylinder upper and lower chambers are communicated through an extension sub-passage in which an extension sub-damping valve and an extension variable orifice are provided. The cylinder lower chamber and the reservoir are communicated through a compression sub-passage in which a compression sub-damping valve and a compression variable orifice are provided.

Abstract: A piston is slidably fitted in a cylinder for dividing the interior of the cylinder into upper and lower cylinder chambers. A reservoir is connected to the piston. A primary passage communicates between the upper cylinder chamber and the reservoir. The primary passage includes a primary damping valve. A secondary passage is connected to the primary passage to bypass the primary damping valve. A constant orifice, a filter, and a damping force adjusting valve are provided in the secondary passage. The primary damping valve includes a pilot line. The pilot line is connected downstream of the filter. The flow resistance of the damping force adjusting valve is directly adjusted by changing the cross sectional flow area of the damping force adjusting valve. The valve opening pressure of the primary damping valve is adjusted by changing the pilot pressure introduced from the pilot line. When the filter becomes clogged, the primary passage ensures the flow of the hydraulic fluid.

Abstract: A damping force control type hydraulic shock absorber of the present invention includes a cylindrical valve member. One end of the cylinder valve member is closed. Also, the shock absorber includes annular inner and outer seal portions, and a valve seat provided there-between, all of which project from an inner wall of a bottom portion of the valve member and are concentric with one another. A disk valve is secured at an inner peripheral portion thereof to the inner seal portion and abuts at an outer peripheral portion thereof on the valve seat. A retainer disk stacks on the disk valve. An annular seal ring abuts at an inner peripheral portion thereof of an outer peripheral edge portion of the retainer disk, and is secured at an outer peripheral portion thereof to the outer seal portion. A blocking member is connected to an open end of the valve member so that a pilot chamber is formed by the retainer disk, the seal ring and the blocking member.

Abstract: The present invention provides a hydraulic shock absorber in which a damping force can be changed nearly linearly as a valve body driven by a proportional solenoid is displaced, by utilizing ports and a oil groove which can easily be formed by a conventional machine tool such as a drilling machine or a lathe. Oil passages and an annular groove connected to the oil passages are formed in a surface of a cylindrical guide portion along which a plunger can slide, and, circular oil passages and an annular groove connected to and offset from the oil passages are formed in a surface of a plunger. The oil passages and annular groove in the plunger can easily be formed by a conventional machine tool such as a drilling machine or a lathe. When an oil path is opened, the oil passages are firstly opened and then the associated annular groove is opened. Thus, a damping force can be changed nearly linearly, and response to the switching of the damping force can be improved.

Abstract: In a damping force control type hydraulic shock absorber, the flow path area of a port is changed by moving a spool according to an electric current supplied to an actuator, and thus the flow path area of a passage between cylinder upper and lower chambers is directly changed, thereby controlling orifice characteristics. Moreover, the pressure in a pilot chamber is changed according to the resulting pressure loss so as to change the valve opening pressure of a disk valve, thereby controlling valve characteristics. This enables the damping force characteristic control range to be widened. The pilot chamber is formed by the side wall of a valve member, the disk valve, a seal disk, and a seal member, also, the seal member has no sliding portion. It is therefore possible to minimize the leakage of hydraulic fluid and to obtain stable damping force characteristics. It is also possible to minimize variations in damping force with temperature changes.

Abstract: A piston is slidably fitted in a cylinder for dividing the interior of the cylinder into upper and lower cylinder chambers. The upper cylinder chamber communicates with the lower cylinder chamber through a check valve. The lower cylinder chamber communicates with a reservoir through a check valve. The upper cylinder chamber communicates with the lower cylinder chamber through an extending side damping valve. The lower cylinder chamber communicates with the reservoir through a contracting side damping valve. A piston rod is connected to the piston. When the piston rod is in an extending stroke, a damping force is generated by the extending side damping valve. When the piston rod is in a compressing stroke, a damping force is generated by the contracting side damping valve. The reservoir includes a connecting hole having an opening. A baffle plate is provided within the reservoir and above the opening of the connecting hole.

Abstract: A system for storing a carrying truck uncoupled from a self-propelled truck moving along a given passage. So that such uncoupled carrying truck may be stored at a storage area outside and angular relative to the passage, the system includes a direction change device disposed at a point of the passage where the carrying truck is uncoupled from the self-propelled truck, and a truck hitching device disposed in the storage area such as to orient towards that point of passage. The direction change device includes a rotary disc member and an elevating element for raising the carrying truck and orienting the same towards the storage area. The truck hitching device includes fore-and-aft movable elements for hitching and drawing the carrying truck which has been changed its direction by the direction change device, towards the storage area.

Abstract: A piston connected to a piston rod is slidably mounted in a cylinder, and a lower cylinder chamber is connected to a reservoir. An extension side passage for communicating an upper cylinder chamber with the lower cylinder chamber and a compression side passage for communicating the cylinder chamber with the reservoir are provided with disc valves, respectively, behind which extension side and compression side back pressure chambers are formed. The extension side back pressure chamber is communicated with the upper and lower cylinder chambers through a fixed orifice and ports. The compression side back pressure chamber is communicated with the lower cylinder chamber and the reservoir through a fixed orifice and ports. By rotating a shutter, flow areas of the ports are changed to adjust orifice features and pressures in the extension side and compression side back pressure chambers are changed to adjust valve features.

Abstract: The present invention is directed to a damping force adjustable hydraulic shock absorber including a cylinder filled with a hydraulic fluid, a piston slidably mounted within the cylinder to divide the interior of the cylinder into two chambers, and a piston rod having one end connected to the piston and the other end extending out of the cylinder. A damping force generating mechanism is provided to communicate between the two chambers and to generate a damping force. A communication passage for communicating one of two chambers in the cylinder with the other chamber and a valve are provided in the communication passage and are adapted to generate the damping force by opening in response to one way flow of the liquid. The shock absorber has a valve opening pressure adjusting mechanism having a back pressure chamber communicating with an upstream portion of the communication passage with respect to the valve.

Abstract: The present invention provides a suspension control device with which the damping coefficient of the suspension can be easily adjusted on the basis of only the vertical vibration of a body of a vehicle, without measurement of the relative velocity or the relative displacement between the body and the wheel along the vertical direction. The absolute velocity of the body 1 is calculated on the basis of the detected signal of the acceleration sensor attached to the body 1, then the rotation angle .theta. of the movable plate is calculated on the basis of the absolute velocity, and the movable plate is rotated in the predetermined direction by the rotation angle .theta.. Accordingly, the damping coefficient is adjusted so that the coefficient in the extension of the shock absorber becomes larger and the coefficient in the compression of the shock absorber becomes smaller, or so that the damping coefficient in the extension becomes smaller and the coefficient in the compression becomes larger.