JPH0419256Y2 - - Google Patents

Description

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

2. Description of the Related Art A shock absorber incorporated in the suspension of a vehicle such as an automobile generally includes a cylinder, a piston, and an orifice configured to allow fluid to pass through when the piston is displaced relative to the cylinder. A damping force is generated by the flow resistance when the fluid passes through the orifice. The damping force of such a shock absorber is preferably a relatively high value in order to reduce so-called fluffy vibrations when the vehicle runs on a flat road, and to reduce so-called fluffy vibrations when the vehicle runs on an uneven road surface. In order to reduce rough vibrations, a relatively low value is preferable.

Problems that the invention aims to solve However, in conventional shock absorbers, the effective passage cross-sectional area of the orifice is generally constant, so the damping force generated by the shock absorber depends on the vertical vibration velocity of the vehicle, that is, the piston It is uniquely determined only by the speed of relative displacement with respect to the cylinder. Therefore, with the conventional shock absorber, it is impossible to obtain a damping force that effectively reduces both the fluffy vibrations and the bumpy vibrations of the vehicle.

In addition, Japanese Utility Model Publication No. 59-8031 filed by the same applicant as the present applicant states that when the piston operating speed is medium, the damping force is reduced to improve ride comfort. A shock absorber is disclosed that is configured to exert a large damping force in addition to improving the ground contact of the tire when the piston speed is high. However, the squishy vibrations of a vehicle occur when the speed and acceleration of the vertical vibration of the vehicle are relatively small, and the bumpy vibrations of a vehicle occur when the speed and acceleration of the vertical vibration of the vehicle are relatively large. Shock absorbers cannot reduce the squishy and bumpy vibrations of a vehicle.

Also, Utility Model Application No. 56-89048, Utility Model Application No. 58-80637,
Japanese Utility Model Application No. 58-102850 discloses a shock absorber which is sensitive to the vertical vibration frequency of a vehicle and whose damping force changes in accordance with the vibration frequency. However, in these shock absorbers, the damping force increases as the vibration frequency increases, so even these shock absorbers cannot reduce the fluffy vibrations and rough vibrations of the vehicle.

Furthermore, JP-A-55-126139 discloses a shock absorber that is sensitive to the resonance frequency of the car body and is configured to reduce damping force in the resonance frequency range of the car body, and that the shock absorber is moved to a neutral position by a pair of springs. A shock absorber is described having a damping force generator including a valve element energized to increase the orifice area as the displacement of the valve element increases.

However, in this shock absorber, the damping force generator is fixed to a piston or cylinder connected to a spring, so the vibration input applied to the wheel from the road surface is not directly transmitted to the damping force generator. It is not until the excitation force is applied to the vehicle body via the shock absorber that the valve element is displaced relative to the housing and the damping force decreases. The vibration input transmitted to the vehicle cannot be effectively reduced, and therefore the vibration of the vehicle body cannot be effectively reduced.

Further, the passage means provided in the housing of the damping force generating device and communicating and connecting the chambers on both sides thereof communicates with the cylinder hole at a portion extending along the reciprocating direction of the valve element on the side of one chamber. are doing. The valve element is therefore also driven by the inertia of the working fluid flowing through the passage means between the two chambers on either side of the housing, so that the orifice area is not always properly controlled and therefore does not necessarily provide the desired damping. The problem is that no force is generated.

Furthermore, in the embodiment shown in FIG. 2 of the above-mentioned publication, communication with the passage means is completely cut off when the valve element is in the neutral position, so that the damping force is not generated. 5 and 6, the outer circumferential surface of the valve element is spaced apart from the wall of the cylinder bore in which it is reciprocally received. Because of this, the valve element tends to be displaced laterally with respect to the direction of its reciprocating motion, which causes the orifice area to change unstably, and the resulting damping force also tends to become unstable.

In view of the above-mentioned problems with conventional shock absorbers, the present invention effectively reduces both the fluffy and bumpy vibrations of the vehicle by controlling the damping force to increase or decrease according to the acceleration of the vertical motion of the wheels. The object of the present invention is to provide an improved shock absorber.

Means for Solving the Problems According to the present invention, the above-mentioned object includes a cylinder connected to one of the sprung mass and the unsprung mass, and a cylinder connected to the other of the sprung mass and the sprung mass. The damping force generating device includes a piston that is fitted so as to be able to reciprocate along the axis, and a damping force generating device that is fixed to the cylinder connected under the spring or the piston, and the damping force generating device is configured to move inside the cylinder. a housing separated into a first chamber and a second chamber; a passage means provided in the housing and having a portion that communicates and connects the first and second chambers and extends in a direction transverse to the axis; a cylinder hole provided in the cylinder hole and extending along the axis across the portion of the passage means; and a cylinder hole disposed within the cylinder hole so as to be reciprocally movable along the axis, communicating the valve chambers on both sides with each other. a valve element having a connecting internal passage; and a pair of springs disposed within the valve chamber to urge the valve element to a neutral position, the valve element having an outer circumferential surface closely engaging the cylinder bore. a notch provided on the outer circumferential surface and defining an orifice that cooperates with the housing to communicate and connect the portion of the passage means and the valve chamber, and the effective passage cross-sectional area of the orifice is equal to This is achieved by a vehicle vertical vibration acceleration sensitive shock absorber configured to increase as the amount of displacement of the valve element from the neutral position increases.

Effects and effects of the invention According to the above-described configuration, the damping force generator is fixed to the cylinder or piston connected under the spring, so when the wheel bounces or rebounds due to vibration input from the road surface, the wheel The vertical movement of the damping force generating device is effectively transmitted to the damping force generating device, and the housing of the damping force generating device moves vertically in substantially synchronization with the bounce and rebound of the wheel.

Particularly when the vehicle runs on a flat road where vibrations are likely to occur, the acceleration of the vertical vibration of the wheels is small, so the valve element moves up and down together with the housing and remains essentially in its neutral position, reducing the effective passage cross-sectional area of the orifice. is maintained at a small value, and the damping force of the shock absorber is maintained at a high value, thereby effectively reducing the squishy vibrations of the vehicle. Furthermore, when the vehicle travels on an uneven road surface that is prone to vibrations, the vertical acceleration of the housing of the damping force generator becomes large, but the valve element substantially tries to maintain its original position due to inertia. As a result, it moves up and down relative to the housing in a direction opposite to that of the housing. As a result, the amount of displacement of the valve element from its neutral position increases, which increases the effective passage cross-sectional area of the orifice and reduces the damping force of the shock absorber. Transmission to the vehicle body via the absorber is suppressed, thereby effectively reducing the rough vibrations of the vehicle.

In addition, the passage means for communicating and connecting the chambers on both sides of the housing opens into the cylinder hole in a direction transverse to the reciprocating direction of the valve element, so that the inertia of the working fluid flowing between the two chambers through the passage means is Therefore, the valve element is not driven, thereby avoiding unnatural fluctuations in the damping force caused by the valve element being driven by the inertia of the working fluid, thereby generating the desired damping force. can be done.

In addition, since the valve element has an outer circumferential surface that tightly engages with the cylinder hole, the valve element is not displaced relative to the housing in a direction transverse to the direction of reciprocating motion, and the effective passage cross-sectional area of the orifice is changes depending only on the amount of displacement of the valve element in the reciprocating direction from the neutral position. Therefore, it is possible to reliably prevent the damping force from becoming unstable due to relative displacement of the valve element with respect to the housing in a direction transverse to its reciprocating direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

Embodiment The attached figure is a longitudinal sectional view showing one embodiment of the shock absorber according to the present invention. In the figure,
Reference numerals 1 and 2 indicate an inner cylinder and an outer cylinder extending concentrically along the axis 3, and both ends of these cylinders are closed by end caps 4 and 5. The cylinders 1, 2 and the end caps 4, 5 cooperate with each other to define an annular chamber 6. A piston 7 is disposed within the inner cylinder 1 so as to be able to reciprocate along an axis 3. The piston 7 cooperates with a damping force generating device 13 to be described later to divide the inside of the inner cylinder 1 into an upper chamber 8 and a lower chamber 9.
It consists of a piston body 10 which is separated into two parts, and a piston rod 11 which is integrally connected to the body and which extends along the axis 3 through the end cap 4. The main body 10 is provided with a communication hole 10a that connects the upper chamber 8 and the lower chamber 9 and allows oil to flow relatively freely between them.

Although not shown in the figure, the piston rod 11
The cylinders 1 and 2 are connected to the vehicle body as a sprung mass at their upper ends, and the cylinders 1 and 2 are connected to a suspension as a sprung mass (not shown in the figure) by bolts 12 integrally fixed to the end cap 5. It is adapted to be connected to a section member.

A damping force generating device 13 is provided at a position close to the lower end of the inner cylinder 1 in the drawing. The damping force generating device 13 includes a housing 14 fixed to the inner cylinder 1, which housing cooperates with the inner cylinder and the end cap 5 to define a lower end chamber 15, which lower end chamber is connected to the inner cylinder 1. It is connected to the annular chamber 6 through a communication hole 16 provided in the annular chamber 6 . The housing 14 is provided with a passage 17 that communicates and connects the lower chamber 9 as the first chamber and the lower end chamber 15 as the second chamber, and the passage has a portion 17a extending along the axis 3 and a lower end chamber 15 as the second chamber. 17
b and portions 17c and 1 extending transversely to axis 3;
It is more similar to 7d. The housing 14 is also formed with a cylinder bore 18 extending along the axis 3 across the sections 17c and 17d, in which a valve element 19 having a certain mass extends along the axis 3. The valve element 19 is arranged to be reciprocally movable, and the valve element 19 tightly engages with the cylinder bore 18 on its outer peripheral surface.

Both ends of the cylinder hole 18 are closed by end plugs 20 and 21, and compression coil springs 22 and 23 are elastically loaded between the end plug 20 and the valve element 19 and between the end plug 21 and the valve element 19, respectively. The valve element 19 is thereby maintained in the neutral position shown.
The end plugs 20 and 21 are screwed to the housing 14, so that the spring force on the valve element 19 can be adjusted.

The valve element 19 is provided with an internal passage 26 which communicates with the valve chambers 24 and 25 on both sides thereof. Further, the outer circumferential surface 27 of the valve element 19 has a substantially passageway 17.
A notch 28 is provided in a portion opposite to the portions 17c and 17d, and the outer circumferential surface 27 and the notch 2
8 cooperate with portions 17c and 17d of passageway 17 to define orifices 29 and 30, respectively. Orifices 29 and 30 are located in portions 17c and 17d when valve element 19 is in the neutral position shown.
is substantially closed by the outer peripheral surface 27, so that its effective passage cross-sectional area is maintained at a small value, and as the amount of vertical displacement of the valve element 19 along the axis 3 increases, its effective passage cross-sectional area decreases. is increasing.

An air chamber 31 is provided at the upper end of the annular chamber 6, and other areas inside the inner cylinder and the outer cylinder are filled with oil as a working fluid.

In the illustrated embodiment, when the vehicle runs on a flat road, the acceleration under the spring is small, so the inertial force acting on the valve element 19 disposed in the inner cylinder connected under the spring is also small. The valve element is thus maintained in the neutral position shown. In this state, when the piston 7 is displaced downward in the figure with respect to the inner cylinder 1 due to the relative movement between the sprung mass and the unsprung mass, the oil in the lower chamber 9 moves to the lower end chamber 15 via the passage 17. However, a relatively large damping force is generated due to the flow resistance when the oil passes through the orifices 29 and 30, and when the piston 7 is displaced upward relative to the inner cylinder 1, the oil in the lower end chamber 15 is The oil moves to the lower chamber 9 via the passage 17, and a relatively large damping force is generated due to the flow resistance when the oil passes through the orifices 30 and 29, thereby effectively reducing the squishy vibrations of the vehicle.

Furthermore, when the vehicle runs on an uneven road surface, the unsprung acceleration is relatively large, and therefore the inertial force acting on the valve element 19 is also large. The amount of displacement of the orifices 29 and 3 increases.
The effective passage cross-sectional area of 0 becomes larger. Now, if we consider the case where an upward load is applied to a wheel (not shown), the inertia force acting on the valve element 19 causes the valve element to displace downward relative to the housing 14, and as a result, the orifice 29 and 30, the effective passage cross-sectional area becomes larger. In this state, the piston 7 is displaced downward relative to the inner cylinder 1, so the oil in the lower chamber 9 moves to the lower end chamber 15 via the passage 17, in which case the oil moves through the orifices 29 and 30 relatively. To circulate freely,
The flow resistance is small, so the damping force is relatively small, and the excitation force applied to the wheels from the road surface is suppressed from being transmitted to the vehicle body via the shock absorber, which effectively reduces the rough vibrations of the vehicle. reduced to Conversely, if a wheel (not shown in the figure) passes through a concave part in the road surface, and the unsprung part is thereby rapidly displaced downward relative to the unsprung part, the upward movement in the figure acting on the valve element 19 occurs. Since the inertial forces on the valve element are relatively large, the valve element is displaced upwardly in the figure, thereby increasing the effective passage cross-sectional area of the orifices 29 and 30. When the piston 7 displaces upward relative to the inner cylinder 1 in such a state, the oil in the lower end chamber 15 moves to the lower chamber 9 via the passage 17, in which case the oil flows through the orifice 3.
0 and 29 can flow relatively freely, the flow resistance at that time is small, and the generated damping force is also small, thereby effectively reducing the rough vibrations of the vehicle.

In the illustrated embodiment, the damping force generating device is provided between the lower chamber 9 and the lower end chamber 15, but the damping force generating device may be incorporated into the piston body 10, in which case. The communication hole 10a is omitted.
Further, the damping force generating device may be provided in the middle of an external conduit that communicates the upper chamber 8 and the lower chamber 9. Further, the shock absorber according to the present invention may be configured as a single cylinder type shock absorber.
Furthermore, in order to effectively reduce the squishy and bumpy vibrations of the vehicle, it is preferable that the effective passage cross-sectional area of the orifice of the damping force generator be controlled in response to the unsprung acceleration. In either case of the single cylinder type, if the damping force generating device is incorporated into the piston body, it is connected in a sprung manner on the piston rod side and sprungly connected on the cylinder side.

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 various other embodiments are possible within the scope of the present invention. This will be clear to those skilled in the art.

[Brief explanation of the drawing]

The attached figure is a longitudinal sectional view showing one embodiment of the vehicle vertical vibration acceleration sensitive shock absorber according to the present invention. 1... Inner cylinder, 2... Outer cylinder, 3... Axis line, 4, 5... End cap, 6
...Annular chamber, 7...Piston, 8...Upper chamber, 9...
... lower chamber, 10 ... piston body, 10a ... communication hole, 11 ... piston rod, 12 ... bolt,
13... damping force generator, 14... housing,
15... Lower end chamber, 16... Communication hole, 17... Passage, 18... Cylinder hole, 19... Valve element, 2
0, 21... End plug, 22, 23... Compression coil spring, 24, 25... Valve chamber, 26... Internal passage, 27... Outer circumferential surface, 28... Notch, 29,
30... Orifice, 31... Air chamber.

Claims (1)

[Scope of utility model registration request] a cylinder connected to one of the sprung mass and the unsprung mass, a piston connected to the other of the sprung mass and the sprung mass and fitted into the cylinder so as to be able to reciprocate along its axis; a damping force generating device fixed to the cylinder or the piston, and the damping force generating device includes a housing that separates the inside of the cylinder into a first chamber and a second chamber; passage means communicating and connecting the first and second chambers and having a portion extending transversely to the axis; and passage means provided within the housing and extending along the axis across the portion of the passage means. a cylinder hole disposed within the cylinder hole; a valve element disposed within the cylinder hole so as to be reciprocally movable along the axis line and having an internal passage that communicates and connects the valve chambers on both sides with each other; and the valve element disposed within the valve chamber. a pair of springs biasing the valve element toward a neutral position, the valve element having an outer circumferential surface closely engaging the cylinder bore, and a pair of springs disposed on the outer circumferential surface and cooperating with the housing to bias the portion of the passage means. and a notch defining an orifice that communicates and connects the valve chamber with the valve chamber,
A vehicle vertical vibration acceleration sensitive shock absorber, wherein the effective passage cross-sectional area of the orifice increases as the amount of displacement of the valve element from the neutral position increases.