JPH0547882Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a suspension of a vehicle such as an automobile, and more particularly to a hydraulic shock absorber incorporated into the suspension.

BACKGROUND ART The applicant of this application has developed a system that acts as a shock absorber in vehicles such as automobiles, and at the same time, when a sudden large load is applied between the sprung mass and the unsprung mass, the rigidity increases to resist the load. In Utility Model Application No. 59-94682 (Utility Model Application No. 61-10220), we proposed an improved hydraulic shock absorber that can better prevent vehicle body from tilting. The hydraulic shock absorber to be proposed in the future will be described in accordance with the structure shown in the drawings attached to this application which shows one embodiment of the present invention. a piston 10 divided into a chamber 11 and a second chamber 12; and a first passage means 1 provided in the piston and communicating and connecting the first and second chambers.
7, a first throttle passage means 18, a liquid passage means 20 leading from the second chamber to the first chamber via the first passage means, and a second throttle passage means 2.
1, a third chamber 8, 6 is connected in communication with the second chamber, and a second chamber allows only the flow of liquid from the third chamber to the second chamber via the second passage means. a check valve 22, a working liquid supply source 37 that supplies high-pressure working liquid, and a working liquid drain 39.
and third passage means 38, 32, 26, 27 for communicating and connecting the working liquid supply source and the first chamber.
and fourth passage means 38, 32, 25, 23 for communicating and connecting the working liquid supply source and the second chamber.
, a return passage means 43 that communicates the third chamber with the working liquid drain, and a first valve device 44 that is provided in the middle of the return passage means and selectively controls communication of the return passage means. In addition to the common configuration, there is a second passageway in the middle of the third passageway that selectively controls communication of the third passageway. A third valve device for selectively controlling communication of the fourth passage means is provided in the middle of the fourth passage means.

According to this configuration, when the first to third valve devices are closed, the same function as a conventional twin inch tube type shock absorber can be obtained. In addition, when a large load acts between the cylinder and the piston in the direction of stretching the shock absorber, the first and second valve devices are opened and the working fluid is supplied from the working fluid supply source through the third passage means. Introducing high-pressure working fluid into the first chamber,
Further, the working fluid is returned from the first chamber to the working fluid drain through the first restricting passage means, the second chamber, the second restricting passage means, the third chamber, the first valve device, and the return passage means. By circulating the working fluid through the piston, the pressure in the first chamber becomes higher than the pressure in the second chamber due to the throttling action of the first restricting passage means, creating a pressure difference on both sides of the piston. Now, let the pressures in the first and second chambers be P ₁ and P ₂ respectively, the effective area of the top surface of the piston (area of the top surface of the piston - cross-sectional area of the piston rod) be A ₁ , and the effective area of the bottom surface of the piston be If A ₂ , then P ₁ A ₁ −P ₂
A force corresponding to A ₂ creates a resistance to the load that tries to stretch the hydraulic shock absorber acting between the cylinder and the piston, so the piston is displaced in the stretching direction relative to the cylinder. The tilt of the vehicle body caused by this is reliably suppressed. Conversely, when a large load acts between the cylinder and the piston in the direction of compressing the shock absorber, the third valve device is opened and the working fluid is supplied from the working fluid supply source through the fourth passage means. When a high-pressure working fluid is introduced into the second chamber, a force is generated in the shock absorber that resists the force exerting on the shock absorber. In this case, when the high pressure working liquid is introduced into the second chamber with the third passage means leading to the first chamber closed,
The pressure in the second chamber can readily pass through the first check valve in a forward direction to the first chamber via the first passage means, so that the pressures in the first and second chambers are approximately equal to each other. However, since the pressure-receiving area on the lower side of the piston is substantially larger than the pressure-receiving area on the upper side of the piston by the cross-sectional area of the piston rod, the pressure in the second chamber P ₂ (the pressure in the first chamber P ₁ approximately equal) and the cross-sectional area of the piston rod A ₃ (equal to A ₂ − _{A 1} )
A force corresponding to _the product _of This suppresses the displacement and the resulting tilting of the vehicle body. In this case, the first valve device may remain closed or open, and even when the first valve device is opened, the working fluid flows from the second valve chamber to the drain via the return passage. Since the flow is throttled by the second throttle device, a high pressure can be maintained in the second chamber if the working liquid is supplied at a sufficiently higher supply rate than the working liquid supply source.

Problems to be Solved by the Invention However, in the hydraulic shock absorber according to the above proposal, when the shock absorber acts as a twin-chub type shock absorber with the first to third valve devices closed. If the degree of constriction of the first and second constriction passage means is determined so as to obtain just the preferable buffering characteristics, the degree of constriction will be relatively gentle. When a hydraulic shock absorber is operated as a locking device against a large extensional or compressive load acting on it, the flow rate of the working fluid must be increased in order for it to function sufficiently as a hydraulic locking device. Therefore, it is necessary to increase the size of the pump that serves as the working fluid supply source. Conversely, if the degree of restriction of the first and second restricting passage means is set to a relatively tight value suitable for the hydraulic shock absorber to act as a hydraulic locking device, the hydraulic shock absorber may be of the normal twin-inch tube type. There is a problem in that the vibration damping force becomes too large when acting as a shock absorber.

In view of the problems mentioned above in the hydraulic shock absorbers proposed earlier, the present invention aims to provide a hydraulic shock absorber that is improved so that these problems do not occur. .

Means for Solving the Problems According to the present invention, the above-mentioned purpose is achieved by, in addition to the common structure with the above-mentioned Utility Application No. 59-94682 (Sho 61-10220), the above-mentioned third and in the middle of the fourth passage means, a first position where the third passage means is placed in communication, a second position where the fourth passage means is placed in communication, and the first and second passage means are placed in the middle of the fourth passage means. a hydraulic shock absorber, characterized in that a second valve arrangement is provided which is switched between a third position in which the chambers are isolated from the source of working fluid and communicated with each other via a third throttle passage means; achieved by.

Effects and Effects of the Invention According to the configuration as described above, when the second valve device is switched to the third position, the first and second chambers are connected to the first throttle passage means. The first throttle passage means are connected to each other through the parallel passage means, so that the first throttle passage means are relatively suitable for operating the hydraulic shock absorber as a locking device against large expansion and contraction loads. Even if the degree of constriction is set to be tight, by setting the degree of constriction of the third constriction passage means to a suitably gentle degree, the first and second chambers can be adjusted when the hydraulic shock absorber operates as a shock absorber. The degree of aperture in between can be set to any relatively gentle degree of aperture.

Embodiments Hereinafter, the present invention will be described in detail with reference to embodiments with reference to the accompanying drawings.

The attached drawing is a schematic diagram showing one embodiment of a hydraulic shock absorber according to the present invention.
shows a shock absorber constructed similarly to a twin-tube type shock absorber,
The shock absorber is a cylindrical base shell 2
The base shell 2 is closed at its upper end by an upper cap 3 and at its lower end by a lower cap 3a, thereby defining an enclosed space inside. A cylindrical cylinder 5 is fixedly disposed inside the base shell 2 along its axis 4. The cylinder 5 is closed at its upper end by the upper cap 3 and at its lower end by the lower cap 3a, thereby defining a chamber space inside, and also defines a cylindrical reservoir chamber 6 in cooperation with the base shell 2, upper cap 3, and lower cap 3a. Oil and compressed air are sealed in the reservoir chamber 6.

A partition wall 7 is fixed to the cylinder 5 at a position close to its lower cap 3a, and a valve chamber 8 is defined between the partition wall and the lower cap. The valve chamber 8 has a plurality of communication holes 9 provided in the cylinder 5.
It is communicatively connected to the reservoir chamber 6 by. Further, a piston 10 is disposed within the cylinder 5 so as to be able to reciprocate along the axis 4, and is fluid-tightly engaged with the inner wall surface of the cylinder via a piston ring (not shown). The piston 10 is defined by the cylinder 5, the upper cap 3, and the partition wall 7, and separates a chamber space filled with oil into an upper chamber 11 and a lower chamber 12. Further, the piston 10 has a main body 13,
A piston rod 15 is connected at one end to the body 13 by a lock nut 14 and extends along the axis 4.
It's getting more and more familiar. The piston rod 15 extends through the upper cap 3, and an oil seal 16 is disposed between the piston rod and the upper cap to seal therebetween.

The main body 13 is provided with a passage 17 and a restriction passage 18 that communicate and connect the upper chamber 11 and the lower chamber 12. There is a passage 1 on the side of the upper chamber of the main body 13 from the lower chamber 12.
A reed-type check valve 19 is provided that only allows oil to flow toward the upper chamber 11 via the valve 7. Similarly, the partition wall 7 is provided with a passage 20 and a throttle passage 21 that communicate and connect the lower chamber 12 and the valve chamber 8 . A reed-type check valve 22 is provided that allows oil to flow only to 12.

The piston rod 15 has a hollow hole 23 extending along the axis 4, into which a tube 24 is inserted and fixed. The hollow hole 23 and the tube 24 cooperate with each other to define an inner passage 25 extending along the axis 4 and an annular outer passage 26. The inner passage 25 communicates at one end with the lower chamber 12 through the hollow hole 23, and the outer passage 26 communicates with the upper chamber 11 at one end through a plurality of radial passages 27 provided in the piston rod 15. . The other end of the inner passage 25 communicates with the outside through a passage 29 provided in a cap 28 fixed to the other end of the piston rod 15.
The outer passage 26 communicates with the outside through a passage 30 provided at the other end of the piston rod 15 and a passage 31 provided in the cap 28.

Although not shown in the figure, the cap 28 is connected to the vehicle body via a mounting eye fixed thereto.
The lower cap 3a is connected to a suspension arm or the like via a mounting eye fixed thereto.

Passages 29 and 31 are connected to conduits 32 and 33, respectively.
It is communicatively connected to the electromagnetic switching valve 34 by.
The switching valve 34 communicates with a reservoir tank 39 for storing oil through a conduit 38 having a flow control valve 35 and an oil pump 37 on its way, and communicates with the reservoir tank 39 through a conduit 41 having a relief valve 40 on its way. There is. The pressure of the oil discharged by the pump 37 and supplied to the flow rate control valve 35 via the conduit 38 is controlled to a predetermined pressure by the pressure control valve 36. The base shell 2 has a communication hole 42 that constantly communicates with the reservoir chamber 6.
The communication hole communicates with the reservoir tank 39 through a conduit 43 that includes a normally closed electromagnetic on-off valve 44 in the middle.

Thus passages 27, 26, 30, 31, conduit 3
3. The switching valve 34 and the conduit 38 constitute a passage means connecting the upper chamber 11 to the working liquid supply source consisting of the pump 37, and the hollow hole 23, the passages 25 and 29, the conduit 32, the switching valve 34, and the conduit 38 constitutes passage means connecting the lower chamber 12 to a working fluid supply source consisting of a pump 37. Further, the conduit conduit 43 including the on-off valve 44 in the middle constitutes a return passage means that connects the chamber space consisting of the valve chamber 8 and the reservoir chamber 6, which are connected to each other through the communication hole 9, to the reservoir tank 39.

When neither of the solenoids 34a and 34b is energized, the switching valve 34 cuts off both the conduits 32 and 33 from communication with the conduits 38 and 41, and connects the conduits 32 and 33 to each other via the throttle 34c. When the solenoid 34a is in the switching position where the solenoid 34a is energized, the switching position is where the conduit 33 and the conduit 38 are connected in communication and the conduit 32 and the conduit 41 are connected, and when the solenoid 34b is energized, The switching position is such that the conduit 32 and the conduit 38 are connected in communication, and the conduit 33 and the conduit 41 are connected in communication. The relief valve 40 opens when the pressure on its upstream side exceeds a predetermined value. This serves to prevent air from inadvertently entering the system from the open end of the conduit 41. The on-off valve 44 is a normally closed on-off valve,
The valve opens when the solenoid 44a is energized.

The switching of the switching valve 34, the opening amount of the flow rate control valve 35, and the opening and closing of the on-off valve 44 are controlled by an electronic control device 45. Electronic control device 45
is detected by a longitudinal acceleration sensor 46 mounted on the vehicle body that detects the acceleration of the vehicle body in the longitudinal direction of the vehicle and a lateral acceleration sensor 47 that detects the acceleration of the vehicle body in the vehicle lateral direction. When the acceleration occurs, a signal indicating the fact and the magnitude of the acceleration is input.

When neither of the sensors 46 and 47 detects an acceleration of a predetermined value or more, the switching valve 34 is in a switching position that connects the conduits 32 and 33 to each other through the throttle 34c. Therefore, in this state, the upper chamber 11 and the lower chamber 12 are connected to each other through the throttle passage 18 and at the same time are connected to each other through the throttle 34c, and the parallel connection of these two throttles creates a throttle passage with a gentle degree of restriction. The hydraulic shock absorbers operate as twin tube shock absorbers with favorable damping properties.

Piston 10 by sensor 46 and/or 47
When it is detected that a large force has been applied to drive the cylinder 5 upward relative to the cylinder 5, the solenoid 34a of the switching valve 34 is energized.
The switching valve connects conduit 33 to conduit 38 in communication;
The conduit 32 is switched to a switching position that connects the conduit 32 in communication with the conduit 41. As a result, high-pressure oil discharged from the oil pump 37 is introduced into the upper chamber 11 through the conduits 38 and 33 and the passages 31, 30, 26, and 27. In this case, the lower chamber 12 is connected to the reservoir tank 39 through the throttle passage 21 and the conduit 43 by opening the on-off valve 44, as in the previous proposal, and the lower chamber 12 is connected to the reservoir tank 39 through the hollow hole. 2
3. Since the passages 25 and 29 and the conduits 32 and 41 are also connected to the reservoir tank 39, even if the degree of restriction of the restriction passage 18 is relatively loose, the differential pressure applied to the upper and lower surfaces of the piston can be kept sufficiently high. can do.

Further, when it is detected by the sensor 46 and/or 47 that a large force that drives the piston 10 downward relative to the cylinder 5 is applied, the solenoid 34b of the switching valve 34 is energized.
the switching valve connects conduit 32 to conduit 38;
The conduit 33 is switched to a switching position in which the conduit 33 is connected in communication with the conduit 41 . As a result, high-pressure oil discharged from the oil pump 37 is introduced into the lower chamber 12 through the conduits 38 and 32, the passages 29 and 25, and the hollow hole 23. At this time, the upper chamber 11 is connected to the passages 27, 26,
30, 31 and conduits 33, 41 to the reservoir tank, the pressure difference between the lower and upper surfaces of the piston becomes large.

The conduit 43 is connected to the reservoir tank 39 independently of the conduit 41, and a check valve that opens when the oil pressure in the reservoir chamber 6 exceeds a predetermined value is provided upstream of the electromagnetic on-off valve 44. A relief valve similar to the relief valve 40 may be provided on the downstream side of the electromagnetic on-off valve 44. Also, the throttle passage 18,
The passage 17 and check valve 19 may be omitted by appropriately setting the effective passage cross-sectional areas of the passage 21 and the throttle 34. Furthermore, the throttle 34c may be provided outside the switching valve 34, and may be configured such that its effective passage cross-sectional area is variably controlled by the electronic control device 45.

Although the present invention has been described above in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and it is understood that various embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art. For example, conduits 33 and 32 may be connected in direct communication with upper chamber 11 and lower chamber 12, respectively.

[Brief explanation of the drawing]

The accompanying drawing is a schematic diagram showing one embodiment of the hydraulic shock absorber according to the present invention. 1... Shock absorber, 2... Base shell, 3... Upper cap, 3a... Lower cap, 4... Axis, 5... Cylinder, 6... Reservoir chamber, 7... Partition wall, 8... Valve chamber, 9 ...Communication hole,
10... Piston, 11... Upper chamber, 12... Lower chamber, 13... Main body, 14... Lock nut, 15
...Piston rod, 16...Oil seal, 1
7... Passage, 18... Throttle passage, 19... Reed valve, 20... Passage, 21... Throttle passage, 22...
Reed valve, 23... hollow hole, 24... tube,
25... Inner passage, 26... Outer passage, 27
... Radial passage, 28 ... Cap, 29,3
0, 31... Passage, 32, 33... Conduit, 34...
...Solenoid switching valve, 34a, 34b...Solenoid,
34c... Throttle, 35... Electromagnetic flow control valve, 36
...Pressure control valve, 37...Oil pump, 38...
... Conduit, 39 ... Reservoir tank, 40 ... Relief valve, 41 ... Conduit, 42 ... Communication hole, 43 ...
... Conduit, 44 ... Electromagnetic on-off valve, 44a ... Solenoid, 45 ... Electronic control device, 46 ... Longitudinal acceleration sensor, 47 ... Lateral acceleration sensor.

Claims (1)

[Claims for Utility Model Registration] A cylinder 5, a piston 10 that divides the interior space of the cylinder into a first chamber 11 and a second chamber 12,
A first passage means 17 and a first throttle passage means 18 are provided in the piston and communicate and connect the first and second chambers, and a first passage means 18 is provided in the piston to communicate and connect the first and second chambers, and from the second chamber through the first passage means. a first check valve 19 that allows liquid to flow only to the chamber; and a second passage means 20.
and a third chamber 8, 6 which is connected to the second chamber by a second throttle passage means 21, and a liquid that flows from the third chamber to the second chamber via the second passage means. a second check valve 22 that only allows the flow of;
Working fluid supply source 37 that supplies high pressure working fluid
a working liquid drain 39; third passage means 38, 33, 26, 27 communicating and connecting the working liquid supply source and the first chamber; and a working liquid drain 39; a fourth passage means 38, 32, 25, 23 that communicates with the third chamber and the working liquid drain; a return passage means 43 that communicates with the third chamber and the working liquid drain; In a depressurizing shock absorber equipped with a first valve device 44 that selectively controls communication of the passage means, the third passage means is placed in a communicating state in the middle of the third and fourth passage means. a first position, a second position in which the fourth passage means are in communication, and a second position in which the first and second chambers are separated from the working fluid supply source and communicated with each other via a third constriction passage means 34c. Hydraulic damping device characterized in that a second valve device 34 is provided which is switched between a third position of communication.